tire pressure for wide rims (i.e. FLO)

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2012-12-21 10:48 AM

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Subject: tire pressure for wide rims (i.e. FLO)

I weigh 150 lbs.  I pretty much always ride 110psi with my current wheels (Shimano R500 with Conti GP4000s 700x23c tires).  That fits in with this chart pretty well.  I have some FLO wheels but haven't mounted everything on them yet.  I've read in a few threads where the guys from FLO ride at 80psi.  That sounds really low to me.  Are there some guidelines for wide rim wheels that dictate lower pressure?  Will I be in any danger riding FLO wheels with the above mentioned Conti tires at 110psi?

2012-12-21 7:34 PM
in reply to: #4544177

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Subject: RE: tire pressure for wide rims (i.e. FLO)
I hope to see some replies about this. From a rolling resistance stand point, I can't see why you want anything but the most amount of psi the tire will old safely
2012-12-21 7:46 PM
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Subject: RE: tire pressure for wide rims (i.e. FLO)

yea i've heard of people putting like 90 psi in their FLO's. i'm still running between 100-110 on mine, same pressure as my old wheels.  seems to be working fine.  

2012-12-21 11:47 PM
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Subject: RE: tire pressure for wide rims (i.e. FLO)
Same as old wheels for me... 110ish
2012-12-22 4:06 AM
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Subject: RE: tire pressure for wide rims (i.e. FLO)
MFConlon - 2012-12-21 9:34 PM

I hope to see some replies about this. From a rolling resistance stand point, I can't see why you want anything but the most amount of psi the tire will old safely


The reason why you don't want as much pressure as the tire/wheel will hold is because unless you are riding on a very smooth surface (like a velodrome), high pressure will be slower than lower pressure as rolling resistance will actually increase.

The sweet spot for most riders seems to be somewhere in the 100-120psi range but is something thay is worth a rider's time to investigate. Also, the road tests into this indicate that a pressure that is a bit lower than optimal is less detrimental than a pressure that is a little higher.

Shane
2012-12-22 4:07 AM
in reply to: #4544748

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Subject: RE: tire pressure for wide rims (i.e. FLO)
DP

Shane

Edited by gsmacleod 2012-12-22 4:09 AM

2012-12-22 5:27 AM
in reply to: #4544177

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Subject: RE: tire pressure for wide rims (i.e. FLO)
I put ~95 in my FLO based on their recommendation.  110 in my others.
2012-12-22 10:36 AM
in reply to: #4544177

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Subject: RE: tire pressure for wide rims (i.e. FLO)

I recall reading something about HED wide rims where HED stated to run PSI 11% lower than you would on a narrow rim.  Will have to find that again. (Found it in the HED FAQ)

I found this over at competitivecyclist.com for the Conti GP4000s:

"A final thing worth mentioning on the sidewall is the recommended tire pressure. It says that 110psi is recommended and 120psi max. Tire pressure is an often-overlooked part of the ride equation and deserves more attention, though at another time. We asked our Conti rep about this, and he tells us that the 110psi is for the average 160lbs male. Lighter should go lower, heavier, higher"

But as Shane said, your road conditions should equate into the psi for comfort.  I ride Felt TTR3's (19mm?) and use ~95 psi (weigh between 175-185) in my GP4000s for the best compromise to ride quality as my training routes are mostly aged & semi-rough (not chip seal though).  Our local race courses have all been repaved the last few years and I've went with ~110 psi for the races without issue.

Use the same psi and then lower and see if it makes a difference for you.



Edited by Donto 2012-12-22 10:37 AM
2012-12-22 9:26 PM
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Subject: RE: tire pressure for wide rims (i.e. FLO)
gsmacleod - 2012-12-22 4:06 AM
MFConlon - 2012-12-21 9:34 PMI hope to see some replies about this. From a rolling resistance stand point, I can't see why you want anything but the most amount of psi the tire will old safely
The reason why you don't want as much pressure as the tire/wheel will hold is because unless you are riding on a very smooth surface (like a velodrome), high pressure will be slower than lower pressure as rolling resistance will actually increase. The sweet spot for most riders seems to be somewhere in the 100-120psi range but is something thay is worth a rider's time to investigate. Also, the road tests into this indicate that a pressure that is a bit lower than optimal is less detrimental than a pressure that is a little higher. Shane
I'm not understanding why. The higher the psi the less contact area you have touching the ground, which to me yields less friction. I'm curious to understand the why behind everythingBased on my weight, tires (vittoria Corsa evo cx tubular corespun 320 tpi) and mixed conditions (normal road), my recommended psi is 130/135.
2012-12-22 10:17 PM
in reply to: #4545533

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Subject: RE: tire pressure for wide rims (i.e. FLO)

MFConlon - 2012-12-22 5:26 PM
gsmacleod - 2012-12-22 4:06 AM
MFConlon - 2012-12-21 9:34 PMI hope to see some replies about this. From a rolling resistance stand point, I can't see why you want anything but the most amount of psi the tire will old safely
The reason why you don't want as much pressure as the tire/wheel will hold is because unless you are riding on a very smooth surface (like a velodrome), high pressure will be slower than lower pressure as rolling resistance will actually increase. The sweet spot for most riders seems to be somewhere in the 100-120psi range but is something thay is worth a rider's time to investigate. Also, the road tests into this indicate that a pressure that is a bit lower than optimal is less detrimental than a pressure that is a little higher. Shane
I'm not understanding why. The higher the psi the less contact area you have touching the ground, which to me yields less friction. I'm curious to understand the why behind everythingBased on my weight, tires (vittoria Corsa evo cx tubular corespun 320 tpi) and mixed conditions (normal road), my recommended psi is 130/135.

This is because on unsmooth roads, too high of a pressure will cause your wheel to bounce, thus loosing contact with the ground temporarily and reducing your forward momentum.  As Shane mentioned, if you're on a perfectly smooth surface, than by all means inflate as much as you can...but in the real world where there are pebbles, cracks, pot holes, etc...you need to account for that.

2012-12-23 9:05 AM
in reply to: #4545564

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Subject: RE: tire pressure for wide rims (i.e. FLO)
Even if you're not losing contact with the ground, with a harder tire you'll still be going up and down to clear all the bumps in the road. Not even just the bumps, but all the imperfections any road will have. It's not a perfectly smooth surface. Think of them as lots & lots of micro hills. The harder the tire, the more you'll be lifted to clear the bumps. Lower pressure will deform and absorb the bump with less vertical movement. So it's a balancing act in finding the right pressure for an appropriate amount of deformation in the tire used.

2012-12-23 10:37 AM
in reply to: #4544177

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Subject: RE: tire pressure for wide rims (i.e. FLO)
In my last set of race wheels (HED Jet c2's) and on my training wheels (Velocity A23) I generally run 95psi rear and 90psi front.  205lbs rider. It's worked very well for me.
2012-12-28 3:11 PM
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Subject: RE: tire pressure for wide rims (i.e. FLO)
michael_runs - 2012-12-21 8:48 AM

I weigh 150 lbs.  I pretty much always ride 110psi with my current wheels (Shimano R500 with Conti GP4000s 700x23c tires).  That fits in with this chart pretty well.  I have some FLO wheels but haven't mounted everything on them yet.  I've read in a few threads where the guys from FLO ride at 80psi.  That sounds really low to me.  Are there some guidelines for wide rim wheels that dictate lower pressure?  Will I be in any danger riding FLO wheels with the above mentioned Conti tires at 110psi?

 

 

We recommend 80-105psi because the rims are wider the rim/tire combo has a larger volume of air.  Think of your mountain bike tires which have a much larger volume.  They are only pumped up to ~40-60psi.  Those surly bikes with the huge tires only get 3-7psi or something ridiculous.  

Bottom line, bigger tire/rim volumes need less psi.  As others have mentioned, going too high effect speed and performance.  I'd experiment in the 80-105psi range and find out what works best for you.

Take care, 

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