# Tire PSI - How Much?



## Cyclin Dan (Sep 24, 2011)

I run mine at 120, but I'm a big guy. The lower the pressure the more compliant the ride will be, but it introduces more rolling resistance and a greater likelihood for pinch flats (and flats in general). 

Your tires will lose air...you need to pump them up before every ride. Mine lose about 10-20 pounds over the course of 1-3 days.


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## Mufasa (Dec 12, 2011)

Hi all. I'm wondering what the pros and cons are of increased or decreased tire pressure. My LBS asked if 105 psi was okay the last time they aired my tires. I said "sure" because I didn't really know what was best (my tires say max 110 I think). After changing a flat yesterday, I got the bike home and put my floor pump on it and noticed that both tires were well below 105. I aired them both to 105 and they seem REALLY rigid. Maybe that's the way they're supposed to be. I'm just wondering if 105 is good and if so, what are the advantages over say, 90 psi?

I'm riding in my first charity ride this weekend so I want the bike to be in top condition and I certainly don't want to be dealing with any flats due to improperly inflated tires!

Thanks for any help!
:thumbsup:


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## wim (Feb 28, 2005)

*Some thoughts.*

Proper tire pressure is a compromise and depends on the size of the tire, the weight of the rider and the surfaces you expect to be riding on. Just as an example: at 145 pounds, I inflate my 700 x 23 tires to 85 psi for general riding around on pavement that ranges from very smooth to pretty crappy chip-and-seal asphalt. I have never had any problems with that. There's a good Michelin chart somewhere on the net relating tire pressure to tire size and rider weight. Too lazy to look for it right now.

_Checking_ tire pressure by attaching a floor pump doesn't really work—the instant you attach the chuck, you lose 10-20 pounds right there. Just pump them up to a good pressure, pull the chuck off and ride. I top mine off once a week or so. Cycling Dan losing 10-20 pounds every 1-3 days is an unusually large pressure drop. He either has a hole in the tube or, what is more likely, he uses his floor pump to _check_ pressure. See above why this doesn't work.

Last thought: too much pressure makes tires hop over irregularities instead of conforming to them. That saps speed and makes for an uncomfortable ride.


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## Mufasa (Dec 12, 2011)

Thanks for the info so far. My test ride after inflating to 105 (I'm 170 pounds) seemed a little stiff.

I found the chart you referring to here:
Michelin Bicycle USA - A better way forward®

It seems, according to the chart, that I should indeed be around 105 but that seemed bumpy.


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## Cyclin Dan (Sep 24, 2011)

wim said:


> Proper tire pressure is a compromise and depends on the size of the tire, the weight of the rider and the surfaces you expect to be riding on. Just as an example: at 145 pounds, I inflate my 700 x 23 tires to 85 psi for general riding around on pavement that ranges from very smooth to pretty crappy chip-and-seal asphalt. I have never had any problems with that. There's a good Michelin chart somewhere on the net relating tire pressure to tire size and rider weight. Too lazy to look for it right now.
> 
> _Checking_ tire pressure by attaching a floor pump doesn't really work—the instant you attach the chuck, you lose 10-20 pounds right there. Just pump them up to a good pressure, pull the chuck off and ride. I top mine off once a week or so. Cycling Dan losing 10-20 pounds every 1-3 days is an unusually large pressure drop. He either has a hole in the tube or, what is more likely, he uses his floor pump to _check_ pressure. See above why this doesn't work.
> 
> Last thought: too much pressure makes tires hop over irregularities instead of conforming to them. That saps speed and makes for an uncomfortable ride.


Wim...I log about 300 miles week and while it is not uncommon for a leak to form in a tire due to some junk picked up on the road, I can assure you that at present I don't have any leaks. I also don't "test" my tire pressure...I just notice what it is when I got to pump up my tires, which as you pointed out is severely flawed because air is lost when engaging the chuck.

I pump my tires up about every other day...maybe every 3rd day, and they are usually between 105 and 110 pounds AFTER HOOKING UP THE CHUCK.

I didn't realize we were getting that scientific about it.


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## Herkwo (Nov 8, 2002)

Tire pressure will depend upon several variables to include rider weight, tire size, and road conditions... Running tires too low may provide a more compliant ride but runs a greater risk of pinch flats.
This link from Michelin provides an excellent baseline for various weights and tire sizes (regardless of manufacturer):
Michelin Bicycle USA - A better way forward®


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## ZoSoSwiM (Mar 7, 2008)

I used to think the higher the PSI the better.. Hell looking back to past threads when I first started riding I even whined about needing a tire that was able to handle more than 120psi...

Now I've turned a 180 and run the lowest pressure I can without pinching or having the tire feel too soft. Running a 25mm tire I'm now running 90/95 for smoother roads and 95/100 for rougher stuff that I might pinch on. I currently weight 170lbs. The lower pressure doesn't "feel" as fast since is doesn't make the ride so jarring. However I've found that I'm more comfortable in the long run so my speed is actually higher.


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## wim (Feb 28, 2005)

Cyclin Dan said:


> I didn't realize we were getting that scientific about it.


No science here I can see. All I'm saying is that many people draw the wrong conclusion. Example: they pump their tires up, say, 100 pounds. The next day, they see a reading of 80 pounds when they're trying to top their tires off and assume (wrongly) that the tire must have lost 20 pounds overnight.


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## Herkwo (Nov 8, 2002)

Mufasa said:


> Thanks for the info so far. My test ride after inflating to 105 (I'm 170 pounds) seemed a little stiff.
> 
> I found the chart you referring to here:
> Michelin Bicycle USA - A better way forward®
> ...


If you want a smoother ride you should look into some 700 x 25c tires. You'll find a more comfy ride w/ a lower rolling resistance w/ only a slight weight increase. I highly recommend the Vittorio Open Corsa CX. A bit pricey but worth every penny... Ribblecycles.co.uk usually has them for ~$40 each.


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## JAG410 (Oct 28, 2008)

how much do you weigh and what tire size is on your bike?


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## wim (Feb 28, 2005)

Herkwo said:


> If you want a smoother ride you should look into some 700 x 25c tires. You'll find a more comfy ride w/ a lower rolling resistance w/ only a slight weight increase.


Not a bad idea. But it should be noted that you need to run the 700 x 25 at a slightly lower pressure than you would a 700 x 23 to get a more comfy ride. A 700 x 25 run at the same pressure than a 700 x 23 would actually ride harsher than the 700 x 23. Now there's some science...


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## cxwrench (Nov 9, 2004)

Cyclin Dan said:


> I run mine at 120, but I'm a big guy. The lower the pressure the more compliant the ride will be, but it *introduces more rolling resistance* and a greater likelihood for pinch flats (and flats in general).
> 
> Your tires will lose air...you need to pump them up before every ride. Mine lose about 10-20 pounds over the course of 1-3 days.


oh man...this again? you are confused about rolling resistance, and could use some advice on tire size. if you're using 23mm tires and pumping them up to 120 to keep from pinch flatting, YOU NEED BIGGER TIRES. plain and simple fact. a 25mm tire at 90-100psi will roll better than your 23mm (i'm guessing) tire at 120. this has been beaten to death for what seems like years on this forum...do a search and you'll find dozens of threads w/ hundreds of replies. 
your tire at 120psi bounces off every imperfection in the road, and that defines rolling resistance. at a more reasonable pressure the tire will conform to the same imperfections and roll smoothly. it will also have much better cornering traction and will be much more comfortable. 
do yourself a favor and get some 25 or even 28mm tires and drop the pressure...you'll see.


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## Cyclin Dan (Sep 24, 2011)

cxwrench said:


> oh man...this again? you are confused about rolling resistance, and could use some advice on tire size. if you're using 23mm tires and pumping them up to 120 to keep from pinch flatting, YOU NEED BIGGER TIRES. plain and simple fact. a 25mm tire at 90-100psi will roll better than your 23mm (i'm guessing) tire at 120. this has been beaten to death for what seems like years on this forum...do a search and you'll find dozens of threads w/ hundreds of replies.
> your tire at 120psi bounces off every imperfection in the road, and that defines rolling resistance. at a more reasonable pressure the tire will conform to the same imperfections and roll smoothly. it will also have much better cornering traction and will be much more comfortable.
> do yourself a favor and get some 25 or even 28mm tires and drop the pressure...you'll see.


Logic in my mind says that a softer/squishier object is going to slow and come to a stop much quicker than a harder, more solid object.

I'm not going to toot my horn and talk about how I have vast knowledge on the matter or anything like that, just going off my own logic. I have logged probably 25,000 miles on 23C tires with 120 lbs of pressure, and never had any real complaint. I am getting ready to buy some new tires, and making the switch over to Conti GP4000S (run Michelin Pro3 Race currently), and I may try 25's. The only real objection I have to 25's is that the tire hangs on the brake pads when it's inflated and you go to remove it from the bike. I have not ran 25's for quite some time, and never on this bike, but I do remember that being an annoyance and one of the reasons I switched to 23's.

So me, being at 230lbs, running an S-Works Tarmac SL3 (Campy SR11 brakes if that matters for the gripe I made up thread), which width of tire and what PSI would YOU recommend running?

I realize the forum has been beat to death with similar posts and theories, but up until now I have mostly ignored them because I haven't really cared for anyone's opinion...what I'd been doing worked. You just happened to catch me on a day when I'm about to replenish my tire supply and feeling curious.

Thanks in advance.


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## Cyclin Dan (Sep 24, 2011)

cxwrench said:


> oh man...this again? you are confused about rolling resistance, and could use some advice on tire size. if you're using 23mm tires and pumping them up to 120 to keep from pinch flatting, YOU NEED BIGGER TIRES. plain and simple fact. a 25mm tire at 90-100psi will roll better than your 23mm (i'm guessing) tire at 120. this has been beaten to death for what seems like years on this forum...do a search and you'll find dozens of threads w/ hundreds of replies.
> your tire at 120psi bounces off every imperfection in the road, and that defines rolling resistance. at a more reasonable pressure the tire will conform to the same imperfections and roll smoothly. it will also have much better cornering traction and will be much more comfortable.
> do yourself a favor and get some 25 or even 28mm tires and drop the pressure...you'll see.


I should also clarify that I have never had a "pinch flat"...just heard tale.


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## Mufasa (Dec 12, 2011)

JAG410 said:


> how much do you weigh and what tire size is on your bike?


23cm tire and I'm 170lbs. The Michelin chart says I should indeed be around the 105 mark.

I agree that it seems like a harder tire would roll faster and more harsh but like Dan, I'm just going off of my typically twisted logic.

In my short riding career, I've gotten one pinch flat from a trail seam that was really high. I knew when I hit it that it would flatten my tire. 

Yesterday I ran over a small nail. Annoying.


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## TiCruiser (Feb 21, 2009)

I'm also a 170lb rider. I've been riding Michelin Tires for years and typically run 15psi less than their charts initial starting suggests. 90-95 in the front and 95-100 in the rear. I spend a lot of time on chipseal so I go a bit soft. I've never pinch flatted.


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## cxwrench (Nov 9, 2004)

Cyclin Dan said:


> Logic in my mind says that a softer/squishier object is going to slow and come to a stop much quicker than a harder, more solid object.
> 
> I'm not going to toot my horn and talk about how I have vast knowledge on the matter or anything like that, just going off my own logic. I have logged probably 25,000 miles on 23C tires with 120 lbs of pressure, and never had any real complaint. I am getting ready to buy some new tires, and making the switch over to Conti GP4000S (run Michelin Pro3 Race currently), and I may try 25's. The only real objection I have to 25's is that the tire hangs on the brake pads when it's inflated and you go to remove it from the bike. I have not ran 25's for quite some time, and never on this bike, but I do remember that being an annoyance and one of the reasons I switched to 23's.
> 
> ...


230lbs...min 25mm tires. how tight do you have your brakes adjusted? you should have absolutely no issues getting the q/r mechanism on the brake lever to open enough to get a 25mm tire out while inflated. if your brakes are so tight you can't, there is some brake set-up advice i could offer as well. 
i would recommend trying 25mm tires at 100rr/90frt. if you ride in a normal road position that should work great, if you're in a very upright position you can drop another 5-10psi from the front. many posters here will back me up on this...and it's been proven by numerous tests...you WILL have less rolling resistance at somewhat lower pressure than what you are running now. it's a simple fact. if you've never tried anything different, how would you ever know? it's free to try it...
what your are thinking is a 'fast' feeling tire is in reality your tire bouncing off of every minor bump/imperfection in the pavement. if the bike AND 230lb rider are going UP, they're not going FORWARD. that defines rolling resistance. this is not just an 'opinion', it's fact.


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## Cyclin Dan (Sep 24, 2011)

cxwrench said:


> if the bike AND 230lb rider are going UP, they're not going FORWARD. that defines rolling resistance. this is not just an 'opinion', it's fact.


I appreciate the advice, and I'll likely give that a try. That said, I'm still having a hard time grasping in my mind how a softer tire is going to roll down the road faster. I understand it will potentially be more comfortable and less jarring (as the tire will absorb impact), but I am still not understanding how a softer more supple object will roll faster. If I roll a "soft and chewy" dog treat across my hand scraped hardwood floor, and I roll a glass marble across my hardwood floor, the marble rolls clear to the end of the floor, hits the wall and starts rolling back. The dog treat, which weighs just as much, doesn't roll half as far. If I roll it hard enough to get it to the wall, it just hits the wall and stops.

I realize this a poor analogy, and I appreciate your input...like I said I WILL try 25's. I just don't understand how the softer, squishier tire rolls down the road FASTER.


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## icsloppl (Aug 25, 2009)

A completely rigid tire is always faster in a strait line than one that is allowed to deform. For anyone who still doesn't understand why i am willing to demonstrate it in a seperate conversation if you like.
A tire that is able to deform to some extent will have a higher cornering limit than the same tire inflated to rigidity on anything other than an absolutely smooth surface. It will also absorb and deflect vibration from the road surface, which most people see as an advantage.
If both of the above are true, then you would seem to want a tire with minimal deflection while riding in a strait line but one with just enough "give" to increase cornering power and improve ride characteristics.
The majority of professionals do set their bikes up this way, and then tend to be very specific in their pressure requirements. You need a good pressure guage, preferably with a bleed feature.
1. Inflate both tires to the maximum indicated value, or at least one that makes the tire completely rigid.
2. Leaning lightly against a wall, mount the bike with your normal gear, clip in your pedals, and take a position on the brake levers.
3. Have a friend slowly reduce one tire's pressure until the tire's contact pact just starts to visably deform. Note the reading.
4. Do the other tire. The pressure readings will normally not be the same.
5. Repeat steps 1,3, and 4 to verify your readings.
6. Add 5psi to each reading. Those are your final values.

At 155lbs (my weight), I usually get something like 97psi front / 103psi rear. Lastly, you may want to try riding a set of fully rigid tires vs. the optimized values. The difference in ride quality should be quite obvious.


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## cxwrench (Nov 9, 2004)

Cyclin Dan said:


> I appreciate the advice, and I'll likely give that a try. That said, I'm still having a hard time grasping in my mind how a softer tire is going to roll down the road faster. I understand it will potentially be more comfortable and less jarring (as the tire will absorb impact), but I am still not understanding how a softer more supple object will roll faster. If I roll a "soft and chewy" dog treat across my hand scraped hardwood floor, and I roll a glass marble across my hardwood floor, the marble rolls clear to the end of the floor, hits the wall and starts rolling back. The dog treat, which weighs just as much, doesn't roll half as far. If I roll it hard enough to get it to the wall, it just hits the wall and stops.
> 
> I realize this a poor analogy, and I appreciate your input...like I said I WILL try 25's. I just don't understand how the softer, squishier tire rolls down the road FASTER.


poor analogy...the floor is much much smoother than the road. track racers on wood velodromes will inflate their tires from 130-140 for mass start races all they way up to 200+ for pursuits. but the track is indeed very smooth. 
go roll the marble down the street and watch it bounce. obviously the dog treat is going to stop sooner because it has less mass as well as being soft. the diffence between 120psi and 90-100psi is much less than the difference between a marble and a dog treat. 
i know you're having a problem wrapping your head around this idea, but like i said...it's fact. plain and simple, proven by testing in real-world conditions. every bump you feel is rolling resistance. if you feel less of a 'bump', there is less rolling resistance. if you dropped the pressure down to 50 or 60psi, then you would be creating some resistance due to energy loss from the flexing of the tire casing. in reality what you're trying to do is let the tire perform the way it was designed to. no pneumatic tire is designed to be used at rock hard pressure on the pavement...on a road bike the flex of the tire is your suspension. you don't want a 'soft & squishy' tire, you just want one that does it's job properly.


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## Jay Strongbow (May 8, 2010)

Cyclin Dan said:


> I appreciate the advice, and I'll likely give that a try. That said, I'm still having a hard time grasping in my mind how a softer tire is going to roll down the road faster. I understand it will potentially be more comfortable and less jarring (as the tire will absorb impact), but I am still not understanding how a softer more supple object will roll faster.


Why do you think tires are made from rubber and filled with air in the first place? If it was a simple case of harder being faster people would be doing time trials on just rims.


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## icsloppl (Aug 25, 2009)

cxwrench said:


> poor analogy...the floor is much much smoother than the road. track racers on wood velodromes will inflate their tires from 130-140 for mass start races all they way up to 200+ for pursuits. but the track is indeed very smooth.
> go roll the marble down the street and watch it bounce. obviously the dog treat is going to stop sooner because it has less mass as well as being soft. the diffence between 120psi and 90-100psi is much less than the difference between a marble and a dog treat.
> i know you're having a problem wrapping your head around this idea, but like i said...it's fact. plain and simple, proven by testing in real-world conditions. every bump you feel is rolling resistance. if you feel less of a 'bump', there is less rolling resistance. if you dropped the pressure down to 50 or 60psi, then you would be creating some resistance due to energy loss from the flexing of the tire casing. in reality what you're trying to do is let the tire perform the way it was designed to. no pneumatic tire is designed to be used at rock hard pressure on the pavement...on a road bike the flex of the tire is your suspension. you don't want a 'soft & squishy' tire, you just want one that does it's job properly.


While the "hopping down the road effect" might make some visual sense, in reality it can't be the case. There are two linked effects that cause this.
1. In order for there to be *any negative effect at all* you would have to assume that the "landing area" is more often on a positve slope than a negative one. In other words, you are more often than not impacting something acts to slow you, such as a saw blade with the tooth angle pointing in against the direction of travel. In reality, the surface is completely chaotic as far as what your tires encounter, and there can be no net effect.
2. The bulk effect of tire deflection is that the deformation area *always* encounters the above effect, and so is slowed by every irregularity in the road surface.

I'm sure this won't help, but at least i tried. :mad2:


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## cxwrench (Nov 9, 2004)

icsloppl said:


> *A completely rigid tire is always faster in a strait line than one that is allowed to deform*. For anyone who still doesn't understand why i am willing to demonstrate it in a seperate conversation if you like.
> A tire that is able to deform to some extent will have a higher cornering limit than the same tire inflated to rigidity on anything other than an absolutely smooth surface. It will also absorb and deflect vibration from the road surface, which most people see as an advantage.
> If both of the above are true, then you would seem to want a tire with minimal deflection while riding in a strait line but one with just enough "give" to increase cornering power and improve ride characteristics.
> The majority of professionals do set their bikes up this way, and then tend to be very specific in their pressure requirements. You need a good pressure guage, preferably with a bleed feature.
> ...


not on real world roads.


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## RJP Diver (Jul 2, 2010)

cxwrench said:


> not on real world roads.


This is the internet... not the real world!

:thumbsup:


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## AndrwSwitch (May 28, 2009)

Sheldon (as always, and RIP) has an article covering the pros and cons of more and less pressure. OP, this is the direct answer to your question. Scroll down to "width and pressure."
http://sheldonbrown.com/tires.html

FWIW, I'm not quite in the "lowest possible pressure" camp, but I inflate to well below max. on most tires. There's a pressure that's low enough for me to start feeling the tire wallow a little when I corner, but that I don't pinch flat when I'm not also carrying a load or something. So I use the lowest pressure that handles well. I have several reasons I think max. pressure is dumb. First, it's really harsh. Nobody's paying me to win races, so I'm going to set up my bike in a way that I enjoy it most. Second, traction's not great. If I'm bouncing and not hooking up, the bike just doesn't handle as well. I like to go fast.  I'd like not to crash. Third, the rolling resistance thing. Generally, the more other random directions something travels in, other than forward, the more energy is wasted. So if I get a smoother ride by lowering my pressure a little, I've probably also made my bike a little more efficient. Doesn't apply to ginormous touring tires that roll like ass, but in a "other things equal" scenario.


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## cxwrench (Nov 9, 2004)

RJP Diver said:


> This is the internet... not the real world!
> 
> :thumbsup:


seriously...i'd love to see icsloppl's 'demonstration' of this claim.


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## Cyclin Dan (Sep 24, 2011)

Jay Strongbow said:


> Why do you think tires are made from rubber and filled with air in the first place? If it was a simple case of harder being faster people would be doing time trials on just rims.


Honestly Jay, I think they'd be solid rubber in a lot of instances if weight weren't a factor. 

Say what you will, I'm still not convinced lower tire pursue that "conforms" to bumps in the road is faster. In fact, I think I'll test my theory this weekend. I know the perfect stretch of road...


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## cxwrench (Nov 9, 2004)

Cyclin Dan said:


> Honestly Jay, I think they'd be solid rubber in a lot of instances if weight weren't a factor.
> 
> Say what you will, I'm still not convinced lower tire pursue that "conforms" to bumps in the road is faster. In fact, I think I'll test my theory this weekend. I know the perfect stretch of road...


how about this...in the cobbled spring classics, riders routinely use larger tires (up to 27mm) at pressures down to 4.5bar...which is just a tad under 70psi. wouldn't you think they'd want really high pressures to keep from flatting on the cobbles? wrong...they use lower pressure to roll over them as smoothly as possible. at this point, you're denying physics being correct. you can be as 'un-convinced' as you want, but you're fighting facts. can't wait to see what you 'think' after this weekend.


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## Yamabushi (Sep 30, 2008)

cxwrench said:


> oh man...this again? you are confused about rolling resistance, and could use some advice on tire size. if you're using 23mm tires and pumping them up to 120 to keep from pinch flatting, YOU NEED BIGGER TIRES. plain and simple fact. a 25mm tire at 90-100psi will roll better than your 23mm (i'm guessing) tire at 120. this has been beaten to death for what seems like years on this forum...do a search and you'll find dozens of threads w/ hundreds of replies.
> your tire at 120psi bounces off every imperfection in the road, and that defines rolling resistance. at a more reasonable pressure the tire will conform to the same imperfections and roll smoothly. it will also have much better cornering traction and will be much more comfortable.
> do yourself a favor and get some 25 or even 28mm tires and drop the pressure...you'll see.





cxwrench said:


> 230lbs...min 25mm tires. how tight do you have your brakes adjusted? you should have absolutely no issues getting the q/r mechanism on the brake lever to open enough to get a 25mm tire out while inflated. if your brakes are so tight you can't, there is some brake set-up advice i could offer as well.
> i would recommend trying 25mm tires at 100rr/90frt. if you ride in a normal road position that should work great, if you're in a very upright position you can drop another 5-10psi from the front. many posters here will back me up on this...and it's been proven by numerous tests...you WILL have less rolling resistance at somewhat lower pressure than what you are running now. it's a simple fact. if you've never tried anything different, how would you ever know? it's free to try it...
> what your are thinking is a 'fast' feeling tire is in reality your tire bouncing off of every minor bump/imperfection in the pavement. if the bike AND 230lb rider are going UP, they're not going FORWARD. that defines rolling resistance. this is not just an 'opinion', it's fact.





cxwrench said:


> poor analogy...the floor is much much smoother than the road. track racers on wood velodromes will inflate their tires from 130-140 for mass start races all they way up to 200+ for pursuits. but the track is indeed very smooth.
> go roll the marble down the street and watch it bounce. obviously the dog treat is going to stop sooner because it has less mass as well as being soft. the diffence between 120psi and 90-100psi is much less than the difference between a marble and a dog treat.
> i know you're having a problem wrapping your head around this idea, but like i said...it's fact. plain and simple, proven by testing in real-world conditions. every bump you feel is rolling resistance. if you feel less of a 'bump', there is less rolling resistance. if you dropped the pressure down to 50 or 60psi, then you would be creating some resistance due to energy loss from the flexing of the tire casing. in reality what you're trying to do is let the tire perform the way it was designed to. no pneumatic tire is designed to be used at rock hard pressure on the pavement...on a road bike the flex of the tire is your suspension. you don't want a 'soft & squishy' tire, you just want one that does it's job properly.





cxwrench said:


> not on real world roads.





cxwrench said:


> seriously...i'd love to see icsloppl's 'demonstration' of this claim.





cxwrench said:


> how about this...in the cobbled spring classics, riders routinely use larger tires (up to 27mm) at pressures down to 4.5bar...which is just a tad under 70psi. wouldn't you think they'd want really high pressures to keep from flatting on the cobbles? wrong...they use lower pressure to roll over them as smoothly as possible. at this point, you're denying physics being correct. you can be as 'un-convinced' as you want, but you're fighting facts. can't wait to see what you 'think' after this weekend.


cxwrench is 100% on the money and correct with all he's said! To those doubting, please suspend your disbelief for just a minute and give it a real world test. If you can't do that, feel free to ride your rock hard tires and enjoy the bone jarring ride, with less control (think high speed technical descents), while simultaneously being slower for the same given effort.


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## milkbaby (Aug 14, 2009)

cxwrench said:


> how about this...in the cobbled spring classics, riders routinely use larger tires (up to 27mm) at pressures down to 4.5bar...which is just a tad under 70psi. wouldn't you think they'd want really high pressures to keep from flatting on the cobbles? wrong...they use lower pressure to roll over them as smoothly as possible. at this point, you're denying physics being correct. you can be as 'un-convinced' as you want, but you're fighting facts. can't wait to see what you 'think' after this weekend.


^THIS!!! Even the pro riders who are very traditional have realized you can't beat physics...


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## cxwrench (Nov 9, 2004)

Cyclin Dan said:


> Honestly Jay, I think they'd be solid rubber in a lot of instances if weight weren't a factor.
> 
> Say what you will, I'm still not convinced lower tire pursue that "conforms" to bumps in the road is faster. In fact, I think I'll test my theory this weekend. I know the perfect stretch of road...


well? how did your test go?


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## cxwrench (Nov 9, 2004)

arrgggghhh...i was waiting all week for this! hope your kid feels better soon, i had bronchitis when i was a kid...no fun.


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## Cyclin Dan (Sep 24, 2011)

cxwrench said:


> well? how did your test go?


One if my kids came down with a horrible fever and bronchitis, so I didn't get the chance to try. 

Will do so soon though.


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