# Does 5 psi really make that much difference?



## HardCharger (Nov 26, 2006)

Though I'd post this here because I'm still fairly new to dedicated road riding. I'm 45 years of age, 5' 10" & 195 lbs. Pretty much a weekend warrior, riding anywhere between 25 to 50 miles per weekend starting (again) since last summer.

Here's the story. I was reading posts over at BF.net & I happened to come across a post over there discussing tire pressure. It got me to interested in changing the psi's in my tires. I usually run 105 psi front & back in the stock 700 x 23mm Vittoria Action HSD folding tires on my F70. I thought this was adequate for speed, traction & ride quality. I thought wrong...

Yesterday, I tried 105 psi in the front & 110 psi in the back, per the information I gathered over at BF. I rode my usual 27-mile (fairly flat) route with light winds & when I finished I noticed my average speed on my cyclometer was up by 1 mph, from 16 mph to 17 mph. I'm thinking how'd this happen? The bike felt like it rode the same to me...

Now I know this doesn't seem like much but to me it is. I was surprised because (I felt like) I rode at the same intensity, no HRM, though. I guess either one of two things (or a combinatioin of both) is happening. Either I'm getting stronger in riding this distance (maybe) or the additional 5 psi in the back really does make a difference. 

I guess after about 450 miles of doing the same thing on my F70, it doesn't hurt to make a change...

Anyone else experience something similar? Should I try even higher pressures not to exceed the maximum?


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## John Nelson (Mar 10, 2006)

No, it doesn't make that much difference.


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## brianmcg (Oct 12, 2002)

Going from 105 to 110 would not give you a 1mph boost. They may feel a little more firm but that would be it.


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## lawrence (May 17, 2005)

Since I started riding a lot, 150-200 miles a week, I've lowered my tire pressure from 110-120 when I started riding to 85-90 in the front tire and 90-100 in the rear tire. I could say by lowering the tire pressure I've gotten faster but that's not true, I've gotten stronger and I have better form.


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## connie (Jul 30, 2006)

Does it make a difference, technically yes. Does it make enough of a difference to account for the bump in average speed you noted given all of the other variables at play, highly doubtful. But, if YOU think it makes a difference, isn't that all that matters?


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## funknuggets (Feb 4, 2004)

This is spot on... there are far too many variables to say whether the psi played any difference, positive or negative in that difference. Wind speed would have more to do with it. Ive seen lots of studies, and basically, the only thing you gain by increasing psi is instability. It makes less of the tire touch the road, it makes the tire less pliant, and thus will "bounce" more when you hit. Plus, its rougher. Alas its far better than having far too low pressure. Optimal pressure from what Ive seen for the average sized cyclist without sacrificing performance or comfort is between 95 and 105. There was a pretty thorough discussion and study over on roadbikerider... with Ed and Fred a few years back that was very practical in its application. Took several riders on identical bikes with differing PSI... and rolled them down the same hill 10 times on each, and measured speed, time, conditions... etc and found no difference in speed/time from 95 and 110 psi bikes.... so, I think the common belief is ... why sacrifice handling and comfort for no performance gain... 

Nonetheless, I am getting verbose. I should have just said... it really wont make a difference.


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## HardCharger (Nov 26, 2006)

*I guess not...*

...judging from the consensus. I'll attribute it to being a bit more inspired yesterday, or I that I am getting stronger as I put more miles on this bike. I've set a higher benchmark for myself to compare my future rides to. Thanks for the replies. 

Like I said originally, I didn't notice any difference in the way the bike handled so I'll stick with this psi combination until I wear these shoes out. One thing I did learn is to run (slightly) different pressures in the front vs. the back. I had been running them equally before.


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## BMF136 (May 7, 2006)

Tire pressures, unless way off, generally will not make that big of a difference in speed. One thing to consider is that when you are new to road riding, or just making a return to it as you said you are, your average speed may not be as high as if you had been riding for several years. When you are new to cycling (lower average speeds) it will be far easier to bump your average speed up by 1mph than it would be for an experienced racer to gain .5mph. In other words, you'll see rapid fitness gains when you first start cycling.


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## funknuggets (Feb 4, 2004)

Hell, what you wear can make that much difference...


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## HardCharger (Nov 26, 2006)

I agree that there may be too many variables to qualify this. I was really looking to hear about performance gains (or not) based on varying tire pressure in the recommended psi range.

One thing for me is I'm not used to inflating road tires over 95 psi as was the case with my old '86 Trek 310 Elance with 27" x 1" rims & tires.

Yes, I did "factor" in my riding gear (which was the same) when I rode each time trying to keep this comparision as apples to apples. I've been averaging just under 16 mph for the past 3 months & to see this marked increase was unexpected. It's not earth shattering but it did indeed surprise me. That's why I thought it might be the psi.

Maybe it's because I chased down & passed two other riders on a flat portion of the ride after having ridden over 25 miles already...


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## bigrider (Jun 27, 2002)

If you ride a lot of tar and chip, 100 psi may be faster than 120 psi.


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## darelldd (Oct 17, 2006)

HardCharger said:


> Maybe it's because I chased down & passed two other riders on a flat portion of the ride after having ridden over 25 miles already...


If I had to put money on the reason - this would be it. "Inspiration" is a MUCH bigger factor in my speed than any piece of equipment. Get some big bad studly guy out there on my radar, and my goal becomes "humiliate him at any cost!" Hey - it is how I stay motivated since I ride alone. 

If I ride alone, I'm happy to do about 18mph. If I constantly have somebody to catch, you'll see me up at 20mph. Sometimes I even check my tire pressure.


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## Kerry Irons (Feb 25, 2002)

*Gauge accuracy?*



HardCharger said:


> ...judging from the consensus. I'll attribute it to being a bit more inspired yesterday, or I that I am getting stronger as I put more miles on this bike. I've set a higher benchmark for myself to compare my future rides to. Thanks for the replies.


As others have said, it wasn't the tire pressure. For that matter, it's a fair question to ask whether your gauge is acurate to 5 psi. IOW, your actual pressure may not have been any different, one ride to the next.


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## Run1stBike2nd (Oct 28, 2005)

bigrider said:


> If you ride a lot of tar and chip, 100 psi may be faster than 120 psi.


Ain't that the truth! Then again, most folks I know who are obsessed w/ high pressure tires would never know that since they'd never consider getting off the smooth stuff. Coarse chip & seal feels good in an almost naughty kind of way.


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## mark_m (Apr 24, 2003)

Kerry Irons said:


> As others have said, it wasn't the tire pressure. For that matter, it's a fair question to ask whether your gauge is acurate to 5 psi. IOW, your actual pressure may not have been any different, one ride to the next.


Good point! Perhaps most geeky question ever but has anybody ever tested their pump gauges? 
~10% error margin at typical roadpressures should be enough, I guess?


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## wankski (Jul 24, 2005)

yep, like others i have actually reduced my tire pressure and i'm much happier... roads here are poor.... ran 105/110 psi f/r now around 90/95.


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## HardCharger (Nov 26, 2006)

*Double checked that...*



Kerry Irons said:


> As others have said, it wasn't the tire pressure. For that matter, it's a fair question to ask whether your gauge is acurate to 5 psi. IOW, your actual pressure may not have been any different, one ride to the next.


...with my digital tire pressure gauge so that's not really the deciding factor. 

The dual-head floor pump with its built-in psi gauge seems to match pressures with the digital psi gauge I use to check all the other tire pressures I have. 

Thanks for bringing it up, though.

I think I'll stay with the 105/110 combo since I didn't notice any difference in the ride quality or cornering, and this takes into account the pavement on my rides is far from being ideal or smooth. In fact, it's in pretty bad shape...


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## uzziefly (Jul 15, 2006)

I ride tubulars and now ride at 95-100psi from my previous 130-140psi last September/October. Any difference? More comfy rides I guess..

That said, OP, maybe the winds changed? Maybe you are stronger. Losta variable factors here. But, just keep on riding dude and you WILL get faster.

Good luck


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## HardCharger (Nov 26, 2006)

uzziefly said:


> I ride tubulars and now ride at 95-100psi from my previous 130-140psi last September/October. Any difference? More comfy rides I guess..
> 
> That said, OP, maybe the winds changed? Maybe you are stronger. Losta variable factors here. But, just keep on riding dude and you WILL get faster.
> 
> Good luck


Thanks for the feedback uzziefly. I'm trying to get out & ride more. If only I didn't have to spend so much time away from the bike. I'm working on that though....

One thing's for sure since having (2) ACL reconstruction surgeries last year, it's now become a life long goal (requirement) to 'Keep Ridin'...


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## lookrider (Dec 3, 2006)

What about tire pressure and punctures?


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## bigrider (Jun 27, 2002)

lookrider said:


> What about tire pressure and punctures?



Depending on your weight, you need to balance tire pressure, tire size, and the roads you ride. To avoid pinch flats you must have enough volume and pressure in the tire so when you hit an object you won't bottom the tire out and get a pinch flat.


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## uzziefly (Jul 15, 2006)

*Wow*



HardCharger said:


> Thanks for the feedback uzziefly. I'm trying to get out & ride more. If only I didn't have to spend so much time away from the bike. I'm working on that though....
> 
> One thing's for sure since having (2) ACL reconstruction surgeries last year, it's now become a life long goal (requirement) to 'Keep Ridin'...



2 ACL reconstructions???!!!! Jeepers!!!!!! Damn man that really sucks. Well, just keep riding on a regular basis and take some time off too to rest and not make it too routine as some people might not like too much routine riding. Vary your rides, routes and such.

Maybe you could cross train or sth as well, like swim,yoga,run etc to keep your fitness level up but cycling and swimming are probably the most knee friendly sports out there. 

Good luck dude :thumbsup:


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## HardCharger (Nov 26, 2006)

uzziefly said:


> 2 ACL reconstructions???!!!! Jeepers!!!!!! Damn man that really sucks. Well, just keep riding on a regular basis and take some time off too to rest and not make it too routine as some people might not like too much routine riding. Vary your rides, routes and such.
> 
> Maybe you could cross train or sth as well, like swim,yoga,run etc to keep your fitness level up but cycling and swimming are probably the most knee friendly sports out there.
> 
> Good luck dude :thumbsup:


Thanks for the encouragement. 

Yeah, '06 was a difficult but a turning point of a year for me. I ruptured my left ACL in '83 while studying martial arts & I kept injuring it over the years even after I stopped practicing. Then I managed to do the same to the right knee in '05 riding my now sold WRF (dirt bike). My main rehab was the stationary trainer, then full on road biking. I was diligent with my PT & conditioning so I progressed rapidly after each operation & I've been doing really well since last Fall.

I got my sports release in Nov '06 so I'm good to go except I've got some advanced articular cartilage damage in the left knee that (I've been warned) I should not aggrivate any further, meaning no running, jumping or cutting. This translates into no high impact activities that I planned on returning to after my surgeries.

Anyway, biking is one of the prescribed methods of exercise that I can do as much as I want to. Conditioning is the key for me now. So now I am focusing on that, as well as returning to surfing, my main sport of choice since I was 13.

I'm glad I found this site. It's helped me "get up to speed" with latest in road bike technology & reading the posts here has enhanced my road riding experience & knowledge. 

Most of the comments & advice given here are insightful, informative & are worthwhile, especially for beginners or folks re-entering the sport like I have. Even those that don't share the same opinions. It's a good thing that people talk about both sides of a particular post so an interested reader take this (or not) into consideration...


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## HardCharger (Nov 26, 2006)

*Pump it up & then back it down*



bigrider said:


> Depending on your weight, you need to balance tire pressure, tire size, and the roads you ride. To avoid pinch flats you must have enough volume and pressure in the tire so when you hit an object you won't bottom the tire out and get a pinch flat.


I'm in that process right now. For me & road riding, I'm erring on the side of caution by keeping them well inflated in the pressure range specified on the tire. I rather have a little rougher ride than get a "snake bite" out on the road...


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## lookrider (Dec 3, 2006)

I'm an idiot! You know, you get a carbon fiber bike to dampen road vibrations but I inflate my tires till they're rock hard. I was reading some of the other forums about tire pressure and there were a lot of great points made about less is more and I'll be damned if they weren't 100% right on.

I ride a Look kg381 with neuvation r28sl2's and conti gp 4000's. I'm 5'10", 170lbs and I was inflating the tires to about 110 psi. The bike rode very nicely to begin with, but when I took about 10 psi out today it was a revelation, an epiphany...The ride was just amazing, otherworldly. I think I can ride with lower pressure, between 90 and 100psi, and the ride will be even better. It just completely eliminated harshness, took the edge off so to speak. I can't believe I didn't come to this conclusion earlier. Everyone is spending many k's on a high tech frame in order to get a compliant ride but it seems like many (myself especially) are ignoring the most obvious, and adjustable, shock absorbing component of the bike; the tires. 

The bike is just planted on the road without all of the chatter and vibrations, handles nicely in the corners, just much more confidence inspiring.

This seems like one of the obvious tips Jack Nicklaus gave. He said to always tee it up if you're given the opportunity. Someone was laughing about how high he teed up an iron shot and he said that its much easier to get the clubhead through air than dirt. Seems obvious but how many players just drop a ball in the tee box of a par three?

It's like these guy's who drive Cadillac Escallades, or other big cars, with low profile tires. I know they want a certain look, but is it worth rattling your fillings and internal organs?

This is one thing that I don't think can be overstated for most riders. Lower your tire pressure. You'll be amazed at the improvement of your ride.


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