Tire Pressure, How much??

[anth]

+1 on the sheldonbrown pressure chart. I use his general guidelines as a starting point and have found the tires perform great.

I figured out what pressures to use through trial and error. Mostly error, as I started with the common mistake that "high pressure=faster" then lowered it after noticing that if I got a bit slack at keeping the tyres pumped up I felt slower but the speedo said otherwise, and got far fewer flats. When I saw that chart I noticed that the numbers were similar to what I ended up at, though I haven't used nearly that wide a range of tyre sizes. As mikesbytes says there is a range of pressures that work fairly well, so I think we all agree that it is a starting point and there is room for some indvidual fine tuning.

Are we looking at 60% on the rear???? 70%??

Good guess. On a road bike it is probably in that range, and may well swing from one to the other depending on whether you are on the tops or the drops. You probably won't go too far wrong if you assume that the rear is carrying twice as much as the front. I think TT/Tri bikes have a fairly even split between wheels when the rider is on the aero bars. I guess some of the more upright bikes must put even more weight on the rear.

If you really want to know put some bathroom scales under one wheel, something a similar height under the other (eg a phone book), get on and read the scales, then swap them around to do the other wheel. These recommendations are hardly an exact prediction of what you should use though, so I wouldn't expect this exercise to achieve much.

 

[sogood]

Do you or anyone else have a good idea as to what percentage of weight the front and rear get? If I am 200lbs (sorry about the non-metric) and my bike with waterbottles and all weighs 25 lbs. That's roughly 225. Are we looking at 60% on the rear???? 70%??

I understand that 40-60 to be the desired weight balance.

 

[Mikebike125]

I rode about 15 minutes before a rain storm came but got a feel for what I did with the pressures. I tried to run 120 in the front and 130 in the rear. That may be too high but I am not sure as I have not figured out what load I have on each wheel. I am planning to try the bathroom scale idea to get me close. In all actuality those numbers should be very close I would think. With those numbers in hand I will interpolate from Sheldons chart and see what figures I come up with.

On a side note, I think I need to replace the rubber on my pump as it does not perfectly seal on the valve when attached. This may skew my pressure numbers.

 

[azdroptop]

81 Kg's I have pretty much always used 120 front and back. For technical crits I air down to 105 110psi. Clinchers

 

[Mikebike125]

All right, I have determined my weight front and rear. I have 92lbs (41.73kg) in the front and 129lbs (58.51kg) in the rear.

So interpolating from Sheldon Browns Chart using a 23mm tire, I should have 110.4psi in the front and 154 in the back....... That sounds wrong....

What is wrong with my math?

 

[likes to ride]

I am 6'2" and weigh 207 pounds currently. I have 700x23 clincher tires, Vittoria, Open Corsa CX, rated at 10 bars. I remember that you can go to 15 psi per bar max. So, max would be 150 psi for a 10 bar tire. I have been pumping mine to 127-130 for years with 10 bar tires. 8 bars I go less of course. In raining conditions I run less tire pressure for better grip through corners. I have not had any problems so far and I like the way it rides. I do have a full carbon bike, bars, and seat post, so the bike is absorbing a harsher ride with higher inflation. Years ago I over pumped my tubulars to 150 psi in a crit and lost it in a corner (lost grip). Like anything else, just try it and see how you like it. I feel like I roll faster at higher inflation but that's my opinion and not matter of fact. On another note I use a separate inflation gauge. I don't trust pumps at all.

 

[artemidorus]

I feel that the optimum for me at 86kg is 90-100psi at the front and 110-120psi at the rear, for 23mm.

 

[hd reynolds]

Im 145lbs. and use 90/95 front/rear pressures on deep section carbon wheels while I use 95/100 on regular aluminum wheelsets. Anything above those feels like i'm sitting on rocks. So with you I guess about the same on the 110max press rated tire. You should also pay attention to a tire's tpi as too low a number makes it less pliant and therefore ride harder on the same pressure than a higher tpi tire.

 

[dm69]

Im 145lbs. and use 90/95 front/rear pressures on deep section carbon wheels while I use 95/100 on regular aluminum wheelsets. Anything above those feels like i'm sitting on rocks. So with you I guess about the same on the 110max press rated tire. You should also pay attention to a tire's tpi as too low a number makes it less pliant and therefore ride harder on the same pressure than a higher tpi tire.

I ride FSA rd488 rims (50mm carbon) with conti comp 22's (vectran) with a specialized roubaix frame. Because of the tubulars and comfy frame I can ride 135/130 psi and still feel comfortable in races!

My old tyres were veloflex carbon's (best tyres ive ridden) and they rolled like butter...didnt matter what pressure you had they were always comfortable, griiped awesome and rolled well. Clinchers on my mavic aluminium wheels and stiff aluminium training bike I only ride 110 psi because they aren't as comfy.

btw im only 68kg's. My recomendtaion by a roubaix and some carbon tubulars with veloflex carbon's...

 

[hd reynolds]

I ride FSA rd488 rims (50mm carbon) with conti comp 22's (vectran) with a specialized roubaix frame. Because of the tubulars and comfy frame I can ride 135/130 psi and still feel comfortable in races!

My old tyres were veloflex carbon's (best tyres ive ridden) and they rolled like butter...didnt matter what pressure you had they were always comfortable, griiped awesome and rolled well. Clinchers on my mavic aluminium wheels and stiff aluminium training bike I only ride 110 psi because they aren't as comfy.

btw im only 68kg's. My recomendtaion by a roubaix and some carbon tubulars with veloflex carbon's...

I agree with you with regards to Veloflex tires as they and Vredestein (Fortesa Comp) make the sweetest rolling tires.

 

[dhk2]

I am 6'2" and weigh 207 pounds currently. I have 700x23 clincher tires, Vittoria, Open Corsa CX, rated at 10 bars. I remember that you can go to 15 psi per bar max. So, max would be 150 psi for a 10 bar tire. I have been pumping mine to 127-130 for years with 10 bar tires. 8 bars I go less of course. In raining conditions I run less tire pressure for better grip through corners. I have not had any problems so far and I like the way it rides. I do have a full carbon bike, bars, and seat post, so the bike is absorbing a harsher ride with higher inflation. Years ago I over pumped my tubulars to 150 psi in a crit and lost it in a corner (lost grip). Like anything else, just try it and see how you like it. I feel like I roll faster at higher inflation but that's my opinion and not matter of fact. On another note I use a separate inflation gauge. I don't trust pumps at all.

A small point, but 10 bar is 145 psi, not 150. Also, some clincher rims (eg, Mavic) have a max rating of 140 psi, at least last time I checked.

Agree high pressures reduce your grip in the wet a lot, but they also reduce roadholding on course surfaces in the dry since your sidewalls can't absorb anything. Plus, IME handling is less secure on high-speed descents. Not to mention your tires much more prone to cuts and punctures at max rated pressures.

Based on opinion of experts, and the few reports I've seen, say that above 120 psi you're not gaining a thing in rolling resistance, in fact may be rolling slower unless the road surface is very smooth.

 

[Mikebike125]

Im 145lbs. and use 90/95 front/rear pressures on deep section carbon wheels while I use 95/100 on regular aluminum wheelsets. Anything above those feels like i'm sitting on rocks. So with you I guess about the same on the 110max press rated tire. You should also pay attention to a tire's tpi as too low a number makes it less pliant and therefore ride harder on the same pressure than a higher tpi tire.

I'm sorry, I couldn't concentrate on anything you were saying because my eyes kept wandering to your little avatar....... WHO is that girl? That can't be real.

 

[Skoorb]

I'm sorry, I couldn't concentrate on anything you were saying because my eyes kept wandering to your little avatar....... WHO is that girl? That can't be real.

Can't speak to it, but I've seen a woman on TV with that kind of development, yep. Obviously not quite natural (and not quite unnasty, either).

 

[dhk2]

Can't speak to it, but I've seen a woman on TV with that kind of development, yep. Obviously not quite natural (and not quite unnasty, either).

Hope those are a couple of volleyballs stuffed under her shirt for a joke. If not, it's the worst case of over-inflation I've ever seen

 

[hd reynolds]

I'm sorry, I couldn't concentrate on anything you were saying because my eyes kept wandering to your little avatar....... WHO is that girl? That can't be real.

Can't speak to it, but I've seen a woman on TV with that kind of development, yep. Obviously not quite natural (and not quite unnasty, either).

Hope those are a couple of volleyballs stuffed under her shirt for a joke. If not, it's the worst case of over-inflation I've ever seen

Missus testing experimental airbags for cyclists.