# Tire rolling resistance test (again)



## aclinjury (Sep 12, 2011)

the conclusion is 25mm tires with HIGHER pressure for lowest rolling resistance.


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## Mike T. (Feb 3, 2004)

Ahhh jeeze here we go again. Thousands of bike riders will be sitting around laptops, looking for the holy grail, instead of where the real gains are - out there riding.


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## MMsRepBike (Apr 1, 2014)

10 of the best performance road tires lab tested - BikeRadar



Ben Delaney said:


> The point is, among the best tires, environmental factors can easily play more of a difference than small, lab-measured rolling resistance differences, even on days with virtually no wind.
> 
> As a 185lb rider, I’ll continue to run my tires between 80 and 100psi for everyday riding — I’m happy to pay one or two watts for more comfort and grip. I can’t feel the loss of one or two watts, but I can feel the difference in 40psi in cushioning.
> 
> ...


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## DrSmile (Jul 22, 2006)

The conclusion I reached after watching and reading the article was that there was no actual discernible difference on the road between the tires. And that Specialized was full of $hit when they said lower pressures are faster.


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## Lombard (May 8, 2014)

Mike T. said:


> Ahhh jeeze here we go again. Thousands of bike riders will be sitting around laptops, looking for the holy grail, instead of where the real gains are - out there riding.



Repped! :thumbsup:


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## aclinjury (Sep 12, 2011)

but quality of a tire should also be more than just rolling resistance. Handling becomes very important under heavy braking too (and this is where I personally think the Conti GP4000s are crap)

But hopefully, this debunks all the guys who say lower pressure means better rolling resistance because a softer tire is now able to conform to the road surface and roll over it easier. False. Just pump up the pressure to as much as your butt can take it. Now, I will say that pressure does have effect on bike handling, but this is another topic.


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## cnardone (Jun 28, 2014)

It may be the best available, but I don't find that the rough drum comes close to replicating the roads I ride. I always thought the idea of the softer tire conforming to the road was speaking to cracks, not just a roughness to the asphalt.


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## Kerry Irons (Feb 25, 2002)

aclinjury said:


> But hopefully, this debunks all the guys who say lower pressure means better rolling resistance because a softer tire is now able to conform to the road surface and roll over it easier. False. Just pump up the pressure to as much as your butt can take it. Now, I will say that pressure does have effect on bike handling, but this is another topic.


Nonsense. Suspension losses increase with pressure and will eventually be larger than the improvements due to reduced hysteresis (casing and rubber flexing) losses. 

Starting with a very low tire pressure, total losses decrease as you increase tire pressure, then bottom out, and then rise again as suspension losses become predominant. This is well documented. In most cases, the sweet spot ranges from roughly 80-110 psi (5.5-7.6 bar). This will obviously vary with road roughness, rider weight, tire casing quality, tread rubber hardness, etc.


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## cooskull (Nov 30, 2013)

cnardone said:


> It may be the best available, but I don't find that the rough drum comes close to replicating the roads I ride. I always thought the idea of the softer tire conforming to the road was speaking to cracks, not just a roughness to the asphalt.


Agreed, I would hardly consider diamond plate steel a suitable model for rough road surfaces- at least for the roads in my area. I've got some chip seal roads around where I live that will rattle your teeth out even when using wide rims and 25c tires at lowish pressures. How hard would it be to make a very realistic test drum with actual chip seal applied?


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## aclinjury (Sep 12, 2011)

Kerry Irons said:


> Nonsense. Suspension losses increase with pressure and will eventually be larger than the improvements due to reduced hysteresis (casing and rubber flexing) losses.
> 
> Starting with a very low tire pressure, total losses decrease as you increase tire pressure, then bottom out, and then rise again as suspension losses become predominant. This is well documented. In most cases, the sweet spot ranges from roughly *80-110 psi* (5.5-7.6 bar). This will obviously vary with road roughness, rider weight, tire casing quality, tread rubber hardness, etc.


80-110 psi is not what I would call "starting with low pressure". I've read people on RBR throwing out numbers 60-70 psi for best rolling resistance, and this is out of your sweet spot.


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## bvber (Apr 23, 2011)

Lombard said:


> Repped! :thumbsup:


I've been seeing such post pop up from time to time and started wondering, doesn't the recipient already get the automated notification? Unless the forum feature has changed recently... :confused5:


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## carlosflanders (Nov 23, 2008)

aclinjury said:


> 80-110 psi is not what I would call "starting with low pressure". I've read people on RBR throwing out numbers 60-70 psi for best rolling resistance, and this is out of your sweet spot.


You read his post wrong. Didn't give any figure for starting at low pressure, that was just to give a starting reference to describe behavior as pressure increases between extremes.


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## Lombard (May 8, 2014)

aclinjury said:


> 80-110 psi is not what I would call "starting with low pressure". I've read people on RBR throwing out numbers 60-70 psi for best rolling resistance, and this is out of your sweet spot.



General and misleading statement. As we all well know and what Kerry stated, that would depend on tire width, rider weight, intended use, etc. While 80-110 PSI might be an ideal range of pressure for 25c tires ridden by a 185lb. rider on average roads, it wouldn't be an ideal range if you change any of said variables - tire width, rider and bike weight, road conditions.

So 60-70 PSI may very well be your ideal pressure for 32c tires ridden on chip seal by the same rider.

As the saying goes, YMMV. And I really doubt that +/-10 PSI will affect rolling resistance very much. So -10 or even -20 PSI from that "rolling resistance sweet spot" for better comfort and handling may very well be a wise choice.


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## Jay Strongbow (May 8, 2010)

So the harder the better. Got it.

I think I'm going to go custom and really take advantage of this: Wheels, Steel Wagon Wheels - Custom Wagons


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## Mike T. (Feb 3, 2004)

Lombard said:


> General and misleading statement. As we all well know and what Kerry stated, that would depend on tire width, rider weight, intended use, etc. While 80-110 PSI might be an ideal range of pressure for 25c tires ridden by a 185lb. rider on average roads, it wouldn't be an ideal range if you change any of said variables - tire width, rider and bike weight, road conditions.
> 
> So 60-70 PSI may very well be your ideal pressure for 32c tires ridden on chip seal by the same rider.
> 
> As the saying goes, YMMV. And I really doubt that +/-10 PSI will affect rolling resistance very much. So -10 or even -20 PSI from that "rolling resistance sweet spot" for better comfort and handling may very well be a wise choice.


Just to chuck in an anecdote about tire pressure, tire pressure variation and surface smoothness in here. It's not totally relevant to the topic but I always found the observation interesting -

7-10 years ago I rode an indoor board track for training and I used Conti Supersonic tires inflated to 130psi. The track surface was smooth plywood. As there were almost no other variables (certainly not wind direction and surface variability anyway) it was very apparent when my tires were not pumped to 130psi. It felt like I was pedaling in cement. It's not often I didn't re-pump before every session but at the times that I did forget, it wasn't many laps before I'd be off the track and topping up the tires.

I once switched tires to some Vreds and they were so bad, compered to my Contis, I switched them back in the track center, before 15 minutes passed. Again, it was like pedaling in cement. All subjective? Yeah maybe.


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## Lombard (May 8, 2014)

Jay Strongbow said:


> So the harder the better. Got it.
> 
> I think I'm going to go custom and really take advantage of this: Wheels, Steel Wagon Wheels - Custom Wagons



Brilliant! And save $$ on tires too!


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## DrSmile (Jul 22, 2006)

I might point out that train wheels work on this same principle, and the rolling resistance for said train wheels is incredibly low (Crr of .001!). I'm going to insist on rails being installed on every bike path.


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## Migen21 (Oct 28, 2014)

aclinjury said:


> But hopefully, this debunks all the guys who say lower pressure means better rolling resistance because a softer tire is now able to conform to the road surface and roll over it easier. False. Just pump up the pressure to as much as your butt can take it. Now, I will say that pressure does have effect on bike handling, but this is another topic.


Ponder this 'science' next time you roll a shopping cart across the rough asphalt parking lot at the grocery store.


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## aclinjury (Sep 12, 2011)

Mike T. said:


> Just to chuck and anecdote about tire pressure, tire pressure variation and surface smoothness in here. It's not totally relevant to the topic but I always found the observation interesting -
> 
> 7-10 years ago I rode an indoor board track for training and I used Conti Supersonic tires inflated to 130psi. The track surface was smooth plywood. As there were almost no other variables (certainly not wind direction and surface variability anyway) it was very apparent when my tires were not pumped to 130psi. It felt like I was pedaling in cement. It's not often I didn't re-pump before every session but at the times that I did forget, it wasn't many laps before I'd be off the track and topping up the tires.
> 
> I once switched tires to some Vreds and they were so bad, compered to my Contis, I switched them back in the track center, before 15 minutes passed. Again, it was like pedaling in cement. All subjective? Yeah maybe.


you ain't alone in feeling this cement. When I switched to using 25mm tires on 25mm rims, I thought I would give the "low pressure" revolution a go. Being that I as under 120 lbs, so I pump it to 60 psi front, 70 psi rear. The theory is that if guys who were much heavier than me saying they were running 70-75 psi on 25c/25mm, I could try 60/70 psi. Pavement here is smooth, nice road overall. During regular dronning in zone3/4 it was fine. But when I went to sprint, especially sprinting up a slight incline, all of the sudden, I felt like the whole bike, both front and rear ends, started to give sideways, taking all confidence in wanting to continue to hammer further. After that, pumped the pressure up to 80/90 front/rear and the swishy-swoosh pretty goes away.


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## bvber (Apr 23, 2011)

Jay Strongbow said:


> So the harder the better. Got it.


No, dude, WIDER! :mad2:

I did see wide ones in that link though.


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## aclinjury (Sep 12, 2011)

Migen21 said:


> Ponder this 'science' next time you roll a shopping cart across the rough asphalt parking lot at the grocery store.


and why ponder? Those guys in the video tested on real road with real bicycle tires. Why should I ponder about shopping cart wheels and not the results in the video? Hmm


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## cnardone (Jun 28, 2014)

I am not racing and shaving a possible millisecond off of my ride does not matter to me. To me, how the ride feels is what is important. 
Having said that, Mike T, ACL - understanding and agreeing that you should ride what feels best, did those feelings of riding in cement translate into any sort of actual change in performance? Isn't that the whole purpose of the video?


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## Mike T. (Feb 3, 2004)

cnardone said:


> I am not racing and shaving a possible millisecond off of my ride does not matter to me. To me, how the ride feels is what is important.
> Having said that, Mike T, ACL - understanding and agreeing that you should ride what feels best, did those feelings of riding in cement translate into any sort of actual change in performance? Isn't that the whole purpose of the video?


How can I, using an indoor track to get in the miles (I know I did a few hundred thousand laps) measure "actual change in performance?" Oh for sure it felt like it was harder to hold 40kph (24mph?) with the lower pressure but short of doing powermeter work or gathering lots of data on track average speeds with both sets of tires at varying pressures, we have no reliable evidence other than "it feels like" - which is not all that bad for us normal people. It might not wash with Team Sky or someone going for the hour record but it's good for me.

As I said before, an indoor board track negates some of the variables that we encounter out on the road where we can never be truly sure whether it's the road surface, wind direction, tire compound or pressure that's making us pedal in cement or zing along.


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## Lombard (May 8, 2014)

bvber said:


> No, dude, WIDER! :mad2:


No, dude! Don't you know anything?? It's DISC BRAKES that make you faster!


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## Z'mer (Oct 28, 2013)

Kerry Irons said:


> Suspension losses increase with pressure and will eventually be larger than the improvements due to reduced hysteresis (casing and rubber flexing) losses.


I agree, but never liked the phrase suspension losses, as it doesn't describe what's appears to be really going on - vertical lift of the bike at high pressure, versus less or none at lower pressure. 

With very high tire pressure, every small bump literally lifts the tire vertically a small amount. The energy to lift the tire (and hence you) has to come from somewhere - your legs. Even if it's a tiny amount of vertical lift, say 1/10 of a mm, string a million of those into a ride and it's measurable. 
At lower pressures, instead of riding up and over the bump, the tire absorbs the bump - and there is less or no lift - lower *relative* rolling resistance.


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## aclinjury (Sep 12, 2011)

cnardone said:


> I am not racing and shaving a possible millisecond off of my ride does not matter to me. To me, how the ride feels is what is important.
> Having said that, Mike T, ACL - understanding and agreeing that you should ride what feels best, did those feelings of riding in cement translate into any sort of actual change in performance? Isn't that the whole purpose of the video?


to me, the swishy feeling of low psi tire is unsettling when doing a hard sprint. You can feel the front end washing side to side, enough so to kill the confidence. And on most of my ride, there is some sprinting involved, and it really takes the fun out of sprinting. Is this counted as a part of performance?


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## carlosflanders (Nov 23, 2008)

I call it tire squirm, and it definitely affects performance. Some tires are more prone to it than others and rim width will also play a part.

Thats why it's a good idea to put 5-10 extra psi in your rear tire for a hill climb, more weight on rear and high torque in low gear at lower cadence will cause extra squirm/ squish.

Similarly, some sprinters will encounter this at high force accelerations and throwing weight around. Need to put in a few extra psi to stop it if it's happening.

we put a bit more air in front tire than expected from weight distribution because downhill cornering can put very large forces on the front tire and cause it to flop, impairing handling.

The outdoor tire tests were done below 10 mph on flagstaff mountain, grades between 7-10%. Probably the worst way to test rolling resistance and will not give useful results. What he showed is that there isn't much of a difference between tires on a hill climb.


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## cnardone (Jun 28, 2014)

aclinjury said:


> to me, the swishy feeling of low psi tire is unsettling when doing a hard sprint. You can feel the front end washing side to side, enough so to kill the confidence. And on most of my ride, there is some sprinting involved, and it really takes the fun out of sprinting. Is this counted as a part of performance?


I think so. I am a firm believer in, "if you are thinking something other than where your focus needs to be, it is probably not a good thing." I am sure there is a better quote somewhere that gets across the point.


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## SPlKE (Sep 10, 2007)

aclinjury said:


> but quality of a tire should also be more than just rolling resistance. *Handling becomes very important under heavy braking too (and this is where I personally think the Conti GP4000s are crap)*
> 
> But hopefully, this debunks all the guys who say lower pressure means better rolling resistance because a softer tire is now able to conform to the road surface and roll over it easier. False. Just pump up the pressure to as much as your butt can take it. Now, I will say that pressure does have effect on bike handling, but this is another topic.


Ditto.

The Vreds I've been riding since I switched over from the gp 4000 crap are much much better in corners and braking. Not just a little bit, or an imaginary bit. Cornering is ridiculously better. Like on rails.


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## Fredrico (Jun 15, 2002)

Mike T. said:


> Just to chuck and anecdote about tire pressure, tire pressure variation and surface smoothness in here. It's not totally relevant to the topic but I always found the observation interesting -
> 
> 7-10 years ago I rode an indoor board track for training and I used Conti Supersonic tires inflated to 130psi. The track surface was smooth plywood. As there were almost no other variables (certainly not wind direction and surface variability anyway) it was very apparent when my tires were not pumped to 130psi. It felt like I was pedaling in cement. It's not often I didn't re-pump before every session but at the times that I did forget, it wasn't many laps before I'd be off the track and topping up the tires.
> 
> I once switched tires to some Vreds and they were so bad, compered to my Contis, I switched them back in the track center, before 15 minutes passed. Again, it was like pedaling in cement. All subjective? Yeah maybe.


Not subjective at all. The tires pumped up hard as rocks rolled over those boards as smooth as glass, and didn't deflect at all under heavy pedaling. :thumbsup: Can't get any faster than that.


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## Lombard (May 8, 2014)

aclinjury said:


> to me, the swishy* feeling* of low psi tire is unsettling when doing a hard sprint. You can feel the front end washing side to side, enough so to kill the confidence. And on most of my ride, there is some sprinting involved, and it really takes the fun out of sprinting. Is this counted as a part of performance?


Read the word I have *bolded*. Now read it again. Now re-read it.

*Feeling* isn't always the same as *reality*. In other words, I am guessing many who are used to bouncing along with bomber pressures describe a little less pressure as feeling "squishy". Many associate this feeling with sluggishness, but in reality, you will not be going any slower.


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## HFroller (Aug 10, 2014)

Lombard said:


> Read the word I have *bolded*. Now read it again. Now re-read it.
> 
> *Feeling* isn't always the same as *reality*. In other words, I am guessing many who are used to bouncing along with bomber pressures describe a little less pressure as feeling "squishy". Many associate this feeling with sluggishness, but in reality, you will not be going any slower.


I tried lowering the pressure too. Up to a point it worked. It was more comfortable. Did it make me faster or slower? Not as far as I know. But beyond that point, the squishiness was real, not a feeling.


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## velodog (Sep 26, 2007)

HFroller said:


> I tried lowering the pressure too. Up to a point it worked. It was more comfortable. Did it make me faster or slower? Not as far as I know. But beyond that point, the squishiness was real, not a feeling.


Well, yeah, the tire pressure can be too low, but it's my understanding that the window of tire performance between to low a pressure and too high a pressure is quite large.


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## Lombard (May 8, 2014)

HFroller said:


> I tried lowering the pressure too. Up to a point it worked. It was more comfortable. Did it make me faster or slower? Not as far as I know. But beyond that point, the squishiness was real, not a feeling.



Ummm, well yeah. If you lower from 100 PSI to 50 PSI, me thinks the squishiness WILL be real.  If a little less is good, much less isn't necessarily better.


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## Kerry Irons (Feb 25, 2002)

Z'mer said:


> I agree, but never liked the phrase suspension losses.


You'll have to take this issue up with the entire scientific literature. It's the term that is used. Sorry.


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## Kerry Irons (Feb 25, 2002)

Lombard said:


> Read the word I have *bolded*. Now read it again. Now re-read it.
> 
> *Feeling* isn't always the same as *reality*. In other words, I am guessing many who are used to bouncing along with bomber pressures describe a little less pressure as feeling "squishy". Many associate this feeling with sluggishness, but in reality, you will not be going any slower.


This cannot be emphasized enough. If I had a dollar for every time someone on this forum posted that "it feels faster" then I could keep myself in tires, chains, and cassettes with no expense. It is amazing that some folks never think that they can used a stopwatch to separate "feelings" from "reality." 

And yes, when pumping your tires hard "feels" faster then pumping them to a rational pressure will "feel" slower. But feelings are not the basis for making performance claims.


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## dmanthree (Aug 22, 2014)

aclinjury said:


> but quality of a tire should also be more than just rolling resistance. Handling becomes very important under heavy braking too (and this is where I personally think the Conti GP4000s are crap)
> 
> But hopefully, this debunks all the guys who say lower pressure means better rolling resistance because a softer tire is now able to conform to the road surface and roll over it easier. False. Just pump up the pressure to as much as your butt can take it. Now, I will say that pressure does have effect on bike handling, but this is another topic.


Funny, I swear by them (the 4000s). I've been riding them for years.

Curious: what do you prefer? Not looking for an argument, just curious.


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## SPlKE (Sep 10, 2007)

dmanthree said:


> Funny, I swear by them (the 4000s). I've been riding them for years.
> 
> Curious: what do you prefer? Not looking for an argument, just curious.


I did too for years... swore by 4000s. I wouldn't consider riding on any other tire.

Then on a whim, I tried some high-end Vreds when I saw them on sale.

I'll never go back to 4000s, or any conti tire for that matter.

Aside from the much stickier high-speed cornering the Vreds could do stupidly better than the 4000s... over time I noticed I was getting a lot fewer flats on the Vreds than I had on the 4000s. When I was a 4000 aficionado, I carried 2 spare tubes at all times, and used both spares on a few long rides. Now as a Vred fanboi, I carry one spare tube, and should probably check it for dry rot one of these days.


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## bvber (Apr 23, 2011)

SPlKE said:


> Now as a Vred fanboi,


Vred as in Vredestein?


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## SPlKE (Sep 10, 2007)

bvber said:


> Vred as in Vredestein?


hehe. Yes. Vredestein. 

I'm a current vred fanboi... but I'm highly critical of tire performance and wear.

The minute I discover vreds are letting me down the way I discovered conti 4000s were letting me down... I'll won't hesitate to dump the vreds, the way I hesitated for years to dump conti 4000s because I was enamored with the lore of conti 4000s so much I couldn't imagine buying any other tire. 

Even now, here on RBR and other bike forums, conti 4000s seem to be the accepted BEST tire by so many people... even though there are many threads with pictures of conti 4000 sidewall failure, people beefing about the high price, and people asking if it's normal to have so many flats.

Anyway, vred fanboi or not, I'm tire-agnostic now. I've learned my lesson about being too brand loyal 

Given the price of good bike tires versus how quickly they wear out... I'll dump vreds in a heartbeat if they get squirrely-slidey in corners and/or start flatting more than I've become accustomed to.

In fact, if any of you riders on this thread have ridden vreds and have a new tire you like better, let me know.


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## Migen21 (Oct 28, 2014)

Are you suggesting that the current Gran Prix 4000 IIs has sidewall integrity issues?

I'd like to see some actual statistics that bare that out.

Sure, there were some reports of damaged sidewalls on the original 4000's, but I haven't seen anything reported recently about this, and considering that the 4000 II (and 4 season) are the two most popular tires on the planet, I really don't know how you can suggest they have issues like this.

I don't know anything about Vred's, so I obviously can't compare. I'm glad you are happy with your tire choice.

I've got about 20k miles over the last few years on 4000II's and 4 Seasons - I've gone through quite a few of them, but none due to any kind of premature failures, and I rarely get flats of any kind. 

Any tire can suffer a sidewall cut. It happens to the best tires. Some are certainly more prone than others. I'd rank the Continental tires pretty high up on the list of durable tires - even the 4000 II race tires.


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## bvber (Apr 23, 2011)

SPlKE said:


> The minute I discover vreds are letting me down the way I discovered conti 4000s were letting me down... I'll won't hesitate to dump the vreds, the way I hesitated for years to dump conti 4000s because I was enamored with the lore of conti 4000s so much I couldn't imagine buying any other tire.


I noticed there are various models of Vred. tires so I'm wondering, which one are you comparing to Conti 4000S?


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## SPlKE (Sep 10, 2007)

bvber said:


> I noticed there are various models of Vred. tires so I'm wondering, which one are you comparing to Conti 4000S?


Various TriComp Fortezza, and one set of TriComp Slicks (no longer made). I have a set of Gran Fondo TriComp tires I picked up half price which I'm going to start riding on in a few weeks.

They're not the cheapest tires. I wait for them to go on sale. The Gran Fondo TriComp are currently 40% off everywhere I looked this morning. Caveat: I haven't ridden the Gran Fondo TriComp yet. If they're crap and Vredestein has pooped the bed, I'll let you know.


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## velodog (Sep 26, 2007)

Another Vred TriComp Fortezza fan here. Have nothing but good to say about them, both handling and wear. Have gotten some good prices for them at Ribble over the years.

But as of late I've been riding a bike with 650b wheels and tires and no Vreds in the size so I went to Compass tires, and have really been happy with them. Some of the best tires I've ridden, but considering the size difference I can't really compare them to the Vreds I've been riding(Vred 700c\23 & 25mm and Compass 650b\42mm), but I put a set of Compass 700\32mm tires on my wives bike and if she has the same good luck I'll try them on my 700c bikes when the time comes.

The smallest Compass 700c tire is 26mm. There is no flat protection and they're a mite pricey, but, in the 650b\42mm that I've been riding I have found them to be outstanding. I mentioned no flat protection, but that has not been an issue in the 42mm tires. I don't know how that will translate to my wives 700\32mm or the 700\26 or 28mm that I would have to use on my bikes that are currently shod in the Vreds, but I have high hopes.

https://www.compasscycle.com/product-category/components/tires/700c/


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## Lombard (May 8, 2014)

SPlKE said:


> The minute I discover vreds are letting me down the way I discovered conti 4000s were letting me down... I'll won't hesitate to dump the vreds, the way I hesitated for years to dump conti 4000s because I was enamored with the lore of conti 4000s so much I couldn't imagine buying any other tire.



This is pretty much the way I am. Right now, I am a Maxxis Re-Fuse fanboi. They are around $35 and I average about one flat per year which is around 3K miles for me. When I do get a flat, I can trace it to either user error or an object that would have punctured the most bulletproof tire you could think of.


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## Jay Strongbow (May 8, 2010)

Lombard said:


> This is pretty much the way I am. Right now, I am a Maxxis Re-Fuse fanboi. They are around $35 and I average about one flat per year which is around 3K miles for me. When I do get a flat, I can trace it to either user error or an object that would have punctured the most bulletproof tire you could think of.


I get that everyone has different priorities but I consider the occasional flat to be part of the sport and don't like trading hundreds of hours of ride quality to avoid maybe a total of 30 min. on the side of the road changing flats.

I get it for commuting but for performance riding I just can't understand the high degree of importance placed on a few less flats.


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## Lombard (May 8, 2014)

Jay Strongbow said:


> I get that everyone has different priorities but I consider the occasional flat to be part of the sport and don't like trading hundreds of hours of ride quality to avoid maybe a total of 30 min. on the side of the road changing flats.
> 
> I get it for commuting but for performance riding I just can't understand the high degree of importance placed on a few less flats.


We agree to disagree. That's what makes the world go round. 

The way I look at it, I am willing to pedal a little harder or go a little slower for the convenience of not having to stop and change flats. Changing a flat in colder weather or on an after work ride when you're racing to get home before dark really sucks.

And the harsher ride of a less supple lower thread count tire can be countered with a little less pressure.


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## Jay Strongbow (May 8, 2010)

Lombard said:


> And the harsher ride of a less supple lower thread count tire can be countered with a little less pressure.


Faulty logic. Pressure can be lowered on good tires too. So harsher tires are harsher tires no matter how you slice it.


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## Lombard (May 8, 2014)

Jay Strongbow said:


> Faulty logic. Pressure can be lowered on good tires too. So harsher tires are harsher tires no matter how you slice it.



True. But like anything else, it's a law of diminishing returns. I run 70 front/100 rear which my hands and my arse are happy with.


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## bvber (Apr 23, 2011)

Lombard said:


> We agree to disagree. That's what makes the world go round.
> 
> The way I look at it, I am willing to pedal a little harder or go a little slower for the convenience of not having to stop and change flats. Changing a flat in colder weather or on an after work ride when you're racing to get home before dark really sucks.


I would say the flat protection is a bigger priority for the commuters than the leisure riders. Although, I went for a leisure ride on local MUT couple of weeks ago when it was balmy 60 degrees F., despite my best effort, I was passed by a young guy wearing full kit & etc. Then about 8 miles later, I passed him. He was on the side of MUT fixing his flat. He turned his head and looked at me with a embarrassed / disappointed look on his face.  I'll bet he was wishing that his tire had better puncture protection...

I wondered what kind of tires he had on to get a flat on MUT that was recently paved and clear of broken glasses or any punctur-able debris.


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## velodog (Sep 26, 2007)

Jay Strongbow said:


> Faulty logic. Pressure can be lowered on good tires too. So harsher tires are harsher tires no matter how you slice it.


True this, a stiff sidewall is a stiff sidewall no matter the air pressure. In fact the stiff sidewall under lower pressure will probably roll more sluggishly than a stiff sidewall with a higher pressure.

A more supple tire with less pressure has a better chance of conforming around a flat hazard than a less supple tire with a higher pressure, which is a flat preventative in it's own right.

Also the thinner thread pattern on the more supple tires have a better chance of deflecting the hazard away from the tire than a more prominent tread pattern, which many protected tires may have, which has the better chance of the debris lodging within the tread, eventually puncturing the tire.


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## n2deep (Mar 23, 2014)

Lombard said:


> We agree to disagree. That's what makes the world go round.
> 
> The way I look at it, I am willing to pedal a little harder or go a little slower for the convenience of not having to stop and change flats. Changing a flat in colder weather or on an after work ride when you're racing to get home before dark really sucks.
> 
> And the harsher ride of a less supple lower thread count tire can be countered with a little less pressure.


Flatting is another subjective topic. I like the GP4000s and oddly enough have experienced significantly less flats with the 4000s than the gatorskins???


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## taodemon (Mar 17, 2014)

Flat protection is probably the last thing on my mind when choosing tires. I've been using gp4000IIs for 3 years without issues. Almost all the flats have been from hitting objects in the road which would have flatted any other tire as well. I tried some S Works tires last year but they felt slower and I ended up going back to the gp4000IIs. If you wait for the sales they have on the different websites the prices aren't that bad either.


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## K Dub Cycle (Oct 22, 2013)

I have been using Vredestein Fortezza Senso All Weather 25mm tires mounted to Campagnolo Bora C17 rims for over 2 years now. I have had exactly one puncture flat from a small piece of glass imbedded in the tread during that time period. So one flat in approximately 10,000 miles. 
I also have Continental GP4000S II 23mm tires mounted to Campagnolo Shamal clinchers that have experienced no puncture flats in several years. 
I use butyl tubes inflated to 90-100 psi and change my tires when they start to get squared off. 
The Continentals scored high for rolling resistance and the Vredesteins were one of the worst for rolling resistance. However I consider other factors such as handling and puncture resistance more important. 


Sent from my iPhone using Tapatalk


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## Z'mer (Oct 28, 2013)

Kerry Irons said:


> You'll have to take this issue up with the entire scientific literature. It's the term that is used. Sorry.


I was only aware of one guy ever really using the term and assumed he was the one that started it. Jan Heine at BQ. 
In the peer reviewed world of scientific literature, I don't think they would count his BQ publication. 
Here's my problem - I think road bike tires as the bike's suspension. More pressure = less suspension (harder ride) and less pressure = more suspension (softer ride). So it's odd to say lower pressure yields less rolling resistance due to suspension losses. 

But Jan Heine explains suspension losses another way, which I don't buy. To me it sounds like some weird unproven theory to explain the effect - 
"Looking through the literature and talking to experts like Jim Papadopoulos, we found a mechanism that could explain this: suspension losses caused by vibrations. As the tissues in the rider’s body rub against each other, friction turns energy into heat. And that energy must come from somewhere: It is taken from the forward momentum of the bike. Your body vibrates, and that slows down the bike. (The bike also vibrates, but it’s not as significant, since it’s mostly made from hard materials that don’t generate much friction.)"

On the other hand, I gave my own explanation why lower pressure = lower resistance above. Which makes more sense to me, I'd call it "small bump lifting losses".


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## DangerousDan (Jun 18, 2016)

I had a sidewall failure on a GP 4000 IIs. It was a 10 mm long tear at the junction of the bead and the sidewall itself. I have no doubt that it was due to a manufacturing defect. It failed after about 2 weeks (200 miles) of riding.

There were no burrs on the rim which might have caused this failure. The tire was replaced by Bike Tires Direct where I bought it.

I have gone through 3 of them in the past two riding seasons. No issues with any others. The replacement for the one that failed is getting close to end of life with no repeat performance.


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## Lombard (May 8, 2014)

Z'mer said:


> Here's my problem - I think road bike tires as the bike's suspension. More pressure = less suspension (harder ride) and less pressure = more suspension (softer ride). So it's odd to say lower pressure yields less rolling resistance due to suspension losses.


It IS odd for a good reason. It's odd because you have it backwards. Lower pressure yields less rolling resistance due to *LESS* suspension losses.

Is this what you meant to say?


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## DrSmile (Jul 22, 2006)

Given the tables in the article:



















Given the slopes of the lines, I have a very hard time understanding how there would be a pressure high enough where the overall energy loss would begin to increase again within the max tire pressure spec. Given that the bike doesn't significantly heat up, any "lift" loss would immediately be returned by gravity. The idea that the human body dissipates frictional heat due to this "lift" is impossible to disprove but seems incredibly unlikely as well. I agree that riding around on 130psi tires may well be uncomfortable, but lots of very light pros ride this pressure and seem to survive grueling 6 hour rides. Also modern components (especially carbon seatposts and bars) are much more compliant and make the ride smoother despite rock hard tires. I tend to ride 105-110psi because at lower pressures I hate the squirmy feel when pushing hard in or out of the saddle, plus I'm lazy and tend to pump up my tires every other, not every day. And of course I don't weigh 125 lbs.

Also given fundamental aerodynamic principles. if you take the same shape and make it narrower (from the front anyways), it will always have a better aerodynamic profile. No matter what wheel manufacturers may say , somehow they aren't comparing apples to apples. Maybe other people experience lots of crosswinds, but God seems to not like me and blasts wind directly in my face.


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## Jay Strongbow (May 8, 2010)

Kerry Irons said:


> This cannot be emphasized enough. If I had a dollar for every time someone on this forum posted that "it feels faster" then I could keep myself in tires, chains, and cassettes with no expense. It is amazing that some folks never think that they can used a stopwatch to separate "feelings" from "reality."
> 
> And yes, when pumping your tires hard "feels" faster then pumping them to a rational pressure will "feel" slower. But feelings are not the basis for making performance claims.


Off topic but that's also why you see so many riders doing themselves a disservice by riding a ultra stiff twitchy carbon bike.
Sharp handling and a super stiff frame definitely feels fast. But if you do rides of any distance the lack of comfort has the opposite effect.


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## Z'mer (Oct 28, 2013)

Lombard said:


> It IS odd for a good reason. It's odd because you have it backwards. Lower pressure yields less rolling resistance due to *LESS* suspension losses.
> 
> Is this what you meant to say?


No. If you have a positive net effect, you normally don't describe it using two negatives. If I make money in a stock trade, I don't say I had less financial losses on that trade. I describe it as a financial gain. 

So if lowering tire pressure = lower rolling resistance, I would call that a suspension gain. 
When designing 2 and 4 wheel vehicle suspensions, The term unsprung weight is used to describe the mass of the wheel/rim and other parts that move up and down over bumps. The goal is to make them weigh substantially less than the weight of the vehicle and passengers. So the vehicle rides flat and level and the suspension components absorb the bumps. 
Same thing happens with a supple bike tire at correct pressure over small road bumps - the minimal weight of the tire casing is accelerated up and down to absorb the rough road surface.


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## Z'mer (Oct 28, 2013)

DrSmile said:


> Given the tables in the article:
> ...I have a very hard time understanding how there would be a pressure high enough where the overall energy loss would begin to increase again within the max tire pressure spec.


There are many problems with correlating tire rolling resistance on round drums with real world conditions on rough surfaces. And the author quoted by the OP did his real world testing comparing one tire against the other. He never tested the same tire at different pressures in the road tests.

The best test for rolling resistance uses real world conditions, power meters, and average many runs. I found a test that did this for MTB tires. This confirms what many have been saying already - if you have super smooth roads, there is a rolling resistance benefit to higher pressures. As the surface gets more uneven, the benefit goes to lower pressure, to a point. 
Mountain Bike Tyre Rolling Resitance

Their results - "reducing tyre pressures does not just leave rolling resistance more or less unaffected, as can be heard here and there, but actually reduces rolling resistance! This is true even on level paths of fine gravel, but the rougher the ground, the greater the effect,"


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## DrSmile (Jul 22, 2006)

Z'mer said:


> There are many problems with correlating tire rolling resistance on round drums with real world conditions on rough surfaces. And the author quoted by the OP did his real world testing comparing one tire against the other. He never tested the same tire at different pressures in the road tests.
> 
> The best test for rolling resistance uses real world conditions, power meters, and average many runs. I found a test that did this for MTB tires. This confirms what many have been saying already - if you have super smooth roads, there is a rolling resistance benefit to higher pressures. As the surface gets more uneven, the benefit goes to lower pressure, to a point.
> 
> Their results - "reducing tyre pressures does not just leave rolling resistance more or less unaffected, as can be heard here and there, but actually reduces rolling resistance! This is true even on level paths of fine gravel, but the rougher the ground, the greater the effect,"


Well I am assuming that one rides on a road, not a meadow... Given the graph you show it seems even more likely that the benefit is pretty linear across the entire psi range, even a very low 30 psi seems to do better than 20, even on a very large MTB tire. Considering that the table stops at 60 psi and the OP's tables start at 70psi, there seems to be no inflection point where lower pressure would be faster on the road "test" surface, at least if you only consider rolling resistance, which is obviously a gross oversimplification.

The argument of course is what exactly constitutes a "road surface" but my impression is that people think that potholes and cracks signify a rougher surface, which isn't really true. The tests done in labs usually greatly exaggerate the surface imperfections precisely to be able to find a measurable difference in the tires, when in reality no practical difference exists under real world conditions.


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## Lombard (May 8, 2014)

Z'mer said:


> No. If you have a positive net effect, you normally don't describe it using two negatives. If I make money in a stock trade, I don't say I had less financial losses on that trade. I describe it as a financial gain.
> 
> So if lowering tire pressure = lower rolling resistance, I would call that a suspension gain.


Bad analogy. Technically, you are right about the above. But I've never heard of anybody describing fewer suspension losses as suspension gains. Just like you never hear of anybody talking about hysteresis gains. And this is neither what you said, nor implied. Let me quote below your original post:



Z'mer said:


> More pressure = less suspension (harder ride) and less pressure = more suspension (softer ride). So it's odd to say lower pressure yields less rolling resistance due to suspension losses.


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## cnardone (Jun 28, 2014)

I've always understood suspension lose to be the loses due to lose of traction when the tire is no longer on the road. The drum simulations just don't seem to replicate that.


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## Lombard (May 8, 2014)

cnardone said:


> I've always understood suspension lose to be the loses due to lose of traction when the tire is no longer on the road. The drum simulations just don't seem to replicate that.


Exactly. The diamond patterned drums simulate roads without imperfections at best. Throw in some imperfections, cracks, broken pavement, chip seal or other real world conditions and you have gone beyond what any of these tests have shown.


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## dmanthree (Aug 22, 2014)

Lombard said:


> No, dude! Don't you know anything?? It's DISC BRAKES that make you faster!


Also, Di2. Yeah. That's it. Unless the battery dies. Then, no.


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## tinball (Sep 24, 2014)

Lombard said:


> Exactly. The diamond patterned drums simulate roads without imperfections at best. Throw in some imperfections, cracks, broken pavement, chip seal or other real world conditions and you have gone beyond what any of these tests have shown.


That thought occured to me as well. I also wonder about the way they are weighting the wheel and tire to the drum. It looks like it's hydraulic and pressed(pulled) down on the drum. A statically pressed weight rather than a hanging weight for example. This gives no other system wide suspension or reaction or transfer of energy to anything but the wheel and the tire. Only the tire and wheel can take absorb the changes in road surface. I wonder how this affects (if at all) compared to the real thing where energy is potentially transferred beyond the wheel. If they had a hanging weight type of test where there potentially might be more vertical movement of the wheel from the rougher surface. I wonder if that would affect the numbers. But I guess that is where the on road test does appear to track with the drum test though. 

Here's their site for more pics of the tire testing equipment: Independent Laboratory Wheel Energy Oy - Rolling Resistance Tests


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## Kerry Irons (Feb 25, 2002)

cnardone said:


> I've always understood suspension lose to be the loses due to lose of traction when the tire is no longer on the road. The drum simulations just don't seem to replicate that.


No. Suspension losses are the energy that is dissipated in the body as road shocks are transmitted to the body. A "perfect" tire would be so compliant that it deformed around any road surface imperfections (no energy transmitted to the rider and therefore no waste) while having zero hysteresis losses due to flexing the casing and tread rubber. No such tire is possible but it explains why suspension losses are important. The tire does not need to lose contact with the road surface in order to transmit energy to the rider.


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## tlg (May 11, 2011)

cnardone said:


> I've always understood suspension lose to be the loses due to lose of traction when the tire is no longer on the road. The drum simulations just don't seem to replicate that.


You're kinda thinking correctly. But the tire need not leave the ground. If you and the bike deflect upwards 1mm, you don't leave the ground. But it takes significant energy to move 150+lbs up 1mm. Now repeat thousands to tens of thousands of times.


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## DrSmile (Jul 22, 2006)

tlg said:


> You're kinda thinking correctly. But the tire need not leave the ground. If you and the bike deflect upwards 1mm, you don't leave the ground. But it takes significant energy to move 150+lbs up 1mm. Now repeat thousands to tens of thousands of times.


This doesn't make any sense. Gravity returns the energy immediately, unless you keep raising the bike up (like going up a hill). The only loss would be due to aerodynamic losses in the vertical direction (possible?) and flex and resulting heat in the frame or the human. Neither one seems likely.


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## tlg (May 11, 2011)

DrSmile said:


> This doesn't make any sense. Gravity returns the energy immediately


Gravity returns the energy, but not in a forward motion. Thus it's energy wasted.


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## Jay Strongbow (May 8, 2010)

DrSmile said:


> This doesn't make any sense. Gravity returns the energy immediately, unless you keep raising the bike up (like going up a hill). The only loss would be due to aerodynamic losses in the vertical direction (possible?) and flex and resulting heat in the frame or the human. Neither one seems likely.


So you saying/thinking rumble strips don't slow down a bike? Go try it.


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## velodog (Sep 26, 2007)

DrSmile said:


> This doesn't make any sense. Gravity returns the energy immediately, unless you keep raising the bike up (like going up a hill). The only loss would be due to aerodynamic losses in the vertical direction (possible?) and flex and resulting heat in the frame or the human. Neither one seems likely.


Think pogo stick. Can burn plenty of energy going up and down with no forward movement.


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## velodog (Sep 26, 2007)

DrSmile said:


> This doesn't make any sense. Gravity returns the energy immediately, unless you keep raising the bike up (like going up a hill). The only loss would be due to aerodynamic losses in the vertical direction (possible?) and flex and resulting heat in the frame or the human. Neither one seems likely.


Look at their arms. Where's that coming from??


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## tlg (May 11, 2011)

velodog said:


> Look at their arms. Where's that coming from??


And.... do you think the energy moving their arms somehow gets returned into the bike as forward motion?
If so, could I shake may arms to make me go faster?


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## velodog (Sep 26, 2007)

tlg said:


> And.... do you think the energy moving their arms somehow gets returned into the bike as forward motion?
> If so, could I shake may arms to make me go faster?


Shake your arms all you want, I'm saying that the movement of their arms is a direct result of the bikes bouncing over the cobbles, suspension losses. A visual of the "resulting heat in the frame or the human" that DrSmile deems unlikely.


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## tlg (May 11, 2011)

velodog said:


> Shake your arms all you want, I'm saying that the movement of their arms is a direct result of the bikes bouncing over the cobbles, suspension losses. A visual of the "resulting heat in the frame or the human" that DrSmile deems unlikely.


I was agreeing with you, and adding to what you said. Energy transmitted vertically isn't returned.


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## velodog (Sep 26, 2007)

tlg said:


> I was agreeing with you, and adding to what you said. Energy transmitted vertically isn't returned.


Sorry, I misunderstood, I just reread what you wrote, and see that now. Excuse me.


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## Lombard (May 8, 2014)

tlg said:


> You're kinda thinking correctly. But the tire need not leave the ground. If you and the bike deflect upwards 1mm, you don't leave the ground. But it takes significant energy to move 150+lbs up 1mm. Now repeat thousands to tens of thousands of times.


........and then think of all the tens of thousands of times that energy was wasted going up and down rather than propelling you forward.


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## Lombard (May 8, 2014)

Jay Strongbow said:


> So you saying/thinking rumble strips don't slow down a bike? Go try it.



Oh yeah, they slow you down alright - especially when hitting them at over 20mph. It stopped her on a dime and she was sent away in an ambulance.


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## DrSmile (Jul 22, 2006)

There are literally gravity batteries that function on this fundamental physics principle. Energy spent moving an object upward against gravity is ALWAYS returned when it comes back down. A bouncing ball loses no energy in it's vertical motion, it loses it only through compression of the ball itself and through aerodynamic loss, plus loss by deformation of the surface it bounces upon.


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## velodog (Sep 26, 2007)

DrSmile said:


> There are literally gravity batteries that function on this fundamental physics principle. Energy spent moving an object upward against gravity is ALWAYS returned when it comes back down. A bouncing ball loses no energy in it's vertical motion, it loses it only through compression of the ball itself and through aerodynamic loss, plus loss by deformation of the surface it bounces upon.


Granted, the energy is not lost, but it is *lost to forward momentum*.


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## tlg (May 11, 2011)

DrSmile said:


> There are literally gravity batteries that function on this fundamental physics principle. Energy spent moving an object upward against gravity is ALWAYS returned when it comes back down. A bouncing ball loses no energy in it's vertical motion, it loses it only through compression of the ball itself and through aerodynamic loss, plus loss by deformation of the surface it bounces upon.


Well you could build a gravity battery into your bike to recapture the vertical energy. Then use it to power a motor to transfer it to forward motion.


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## DrSmile (Jul 22, 2006)

velodog said:


> Granted, the energy is not lost, but it is *lost to forward momentum*.


If it converts horizontal energy to vertical energy then I would argue that it must be returned to forward momentum on it's downward return, why would it only work that way on it's way up?


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## DrSmile (Jul 22, 2006)

tlg said:


> Well you could build a gravity battery into your bike to recapture the vertical energy. Then use it to power a motor to transfer it to forward motion.


Let's patent a bounce battery. The BMX guys would love it.


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## tlg (May 11, 2011)

DrSmile said:


> If it converts horizontal energy to vertical energy then I would argue that it must be returned to forward momentum on it's downward return, why would it only work that way on it's way up?


Your argument would be unequivocally wrong. 
The horizontal force is transferred to vertical because of bumps. You'd need perfectly placed bumps to transfer it the other way.


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## Z'mer (Oct 28, 2013)

DrSmile said:


> If it converts horizontal energy to vertical energy then I would argue that it must be returned to forward momentum on it's downward return, why would it only work that way on it's way up?


The problem is certainly an interesting one to think about, especially from a physics point of view. But remember we are not dealing with rigid, linear bodies in a zero loss environment. 

From a practical point of view, most would agree, even without trying it - normally riding over a parking lot full of wood 2 X 4s spaced every 2 feet at 10 mph would take a lot more power (watts) than maintaining 10 mph over the same "smooth" distance with no bumps. In a perfect situation with no losses, it would, "in theory" be the same. 

Now let's change the "mind" test slightly - say we space the 2 x 4's every 10 feet, and we do 2 tests 
1) one where cyclist rides normally over the 2 x 4s at 10 mph - measure power
2) another where he bunny hops expertly over the 2 x 4s at 10 mph, missing them entirely - measure power. 
Again, most cyclists would correctly guess that doing 2) would take less power. 
So why?


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## Jay Strongbow (May 8, 2010)

DrSmile said:


> If it converts horizontal energy to vertical energy then I would argue that it must be returned to forward momentum on it's downward return, why would it only work that way on it's way up?


Sometimes common sense shouldn't be ignored. But hey if you want to build a case that rough roads are as fast as smooth roads then have at it.


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## cooskull (Nov 30, 2013)

Z'mer said:


> The problem is certainly an interesting one to think about, especially from a physics point of view. But remember we are not dealing with rigid, linear bodies in a zero loss environment.
> 
> From a practical point of view, most would agree, even without trying it - normally riding over a parking lot full of wood 2 X 4s spaced every 2 feet at 10 mph would take a lot more power (watts) than maintaining 10 mph over the same "smooth" distance with no bumps. In a perfect situation with no losses, it would, "in theory" be the same.
> 
> ...


Measure the power with what? Bike power meters aren't going to be able to measure the energy/power needed to lift the bike several inches off the ground to clear the 2x4s.


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## Z'mer (Oct 28, 2013)

cooskull said:


> Measure the power with what? Bike power meters aren't going to be able to measure the energy/power needed to lift the bike several inches off the ground to clear the 2x4s.


Yep, but for that sake of this test, assume that the power needed to lift the bike is somehow measured, and found to be very low in comparison to the power difference measured by a power meter in both test cases. 
I'm trying to point out that bunny hopping is very much like having a fine tuned suspension that would need to lift only a small weight (say the bike at 18 lbs) to clear bumps versus needing to lift the bike + rider weight (say 190 lbs) to clear them.


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## velodog (Sep 26, 2007)

Z'mer said:


> Yep, but for that sake of this test, assume that the power needed to lift the bike is somehow measured, and found to be very low in comparison to the power difference measured by a power meter in both test cases.
> I'm trying to point out that bunny hopping is very much like having a fine tuned suspension that would need to lift only a small weight (say the bike at 18 lbs) to clear bumps versus needing to lift the bike + rider weight (say 190 lbs) to clear them.


Why not find a freshly resurfaced road with rumble strips cut into the shoulder and ride, say two miles, on a bike with a power meter, on the rumble strips for the whole two mile at a constant power. Then go back and ride the same two miles, in the same direction, at the same constant power, except this time riding on the fresh smooth surface beside the rumble strip and see which is traversed at the higher speed.


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## cooskull (Nov 30, 2013)

velodog said:


> Why not find a freshly resurfaced road with rumble strips cut into the shoulder and ride, say two miles, on a bike with a power meter, on the rumble strips for the whole two mile at a constant power. Then go back and ride the same two miles, in the same direction, at the same constant power, except this time riding on the fresh smooth surface beside the rumble strip and see which is traversed at the higher speed.


I'd hate to be the guy riding 2 miles of rumble strip... at least if you ever wanted to have children in the future 

Anyways, don't forgot to pump up the 23c tires to 140 PSI for maximum efficiency :thumbsup:


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## Lombard (May 8, 2014)

Jay Strongbow said:


> Sometimes common sense shouldn't be ignored. But hey if you want to build a case that rough roads are as fast as smooth roads then have at it.


Sometimes common sense isn't so common.


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