PSA, Inflate tire to 80% psi
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I'm skeptical of ALL of the tire info I read. Riding sewups I never used a gauge, then when I recently switched to a bike with tubes I started following the various charts, all of which put me under max by quite a bit. I read all of the advice, followed it, felt that my bike was really draggy. One day I pumped up to 100% and dropped 5 minutes off my daily half-hour commute. Immediately and consistently, not a one-up. It's a little stiff, but I came from sewups to 35mm tires, so c'mon, how bad is it really? Screw the charts, screw the people who are saying my tires aren't in contact a lot of the time and therefore I'm losing and don't know it: the clock don't lie, and I'm less beat when I get there.
Last edited by mdarnton; 05-20-23 at 09:01 AM.
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Enjoying the way a bike feels is as good a reason as any to choose a pressure. We don't all need optimal speed, grip, tire life or whatever factors the mavens consider when coming up with charts. It's smart to start with the expert advice, then run with the subjective as far as you like.
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Some people think all roads are chip seal with 3/4" or bigger aggregate. In such conditions and even with 1/2" size aggregate, I do lower my tire pressure. However most of the roads around here are made with very much finer aggregate, not much bigger than just sand, in the top layer. So I too have found that higher tire pressure than the "never wrong" tire pressure calculators that don't take everything into account, lets me be ever so slightly faster with less strain on my leg muscles.
Last edited by Iride01; 05-20-23 at 11:14 AM.
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Some people think all roads are chip seal with 3/4" or bigger aggregate. In such conditions and even with 1/2" size aggregate, I do lower my tire pressure. However most of the roads around here are made with very much finer aggregate, not much bigger than just sand, in the top layer. So I too have found that higher tire pressure than the "never wrong" tire pressure calculators that don't take everything into account, lets me be ever so slightly faster with less strain on my leg muscles.
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No; the reason solid tires are slow is because of hysteresis losses in the tire material. A pneumatic tire has far less solid material, and correspondingly lower hysteresis losses. A high pressure can lower rolling resistance, but depending on the road surface, at the expense of comfort and control.
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at 280lbs even I don't run my tires that high anymore, 35/30, all about tires conforming to the surface. Interesting to me is that I used to run 26x1.95 at 50psi in my 20s and dented so many wheels, had lousy times in races and really poor handling ability. Didn't mtb in my 30s except on the cross bike from time to time. Picked up a modern 29er running 2.25 and not only do I have faster times but I ride much more technical terrain and have yet to dent a rim. I find MTBing much more enjoyable now.
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Not true any more, wider, low profile tires use higher pressures. The wife's minivan with 17" rims uses 40psi, tires say 44psi but the door panel says different. Mine minivan (same make/model) with 16" wheels uses 35psi, 3psi below the tire recommendation. While my miata's tires say max of 50psi on 17" wheels, car says 40, but the usual driver recommendation is 30psi since the car weights 2300lbs and literally bounces around the road at higher, and screw tread life, its all about the handling.
The pressure you use is the one on the door panel and in the manual. Not the one on the tire, or some fictional third pressure you've invented between the two.
As with bikes, tire pressure is set in proportion to the weight on the axle, adjusted for tire volume. So a 4000lbs minivan will have a higher psi than a sports car for the same 225R17 tire size, just as a heavy rider will use a higher air pressure in his 700x19c tires than a lighter rider. Larger volume tires require lower pressures to create the same pneumatic 'pre-load' as a smaller tire.
Beyond that, I don't have a clue what you are talking about. But I suggest you read your car manual.
#63
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One of my conundrums: I feel there is conflicting evidence for lower tire pressures being beneficial. These two sources seem to indicate that higher pressures create less rolling resistance.
https://www.velonews.com/gear/resist...ce/?scope=anon
https://www.bicyclerollingresistance...-tr-comparison
Additionally, in all of Bicycle Roiling Resistance's road tire tests resistance is reduced with increasing pressure. I'm not a subscriber and some of the results are shielded but that's true from their extra high to ultra high pressure categories.
Thoughts?
https://www.velonews.com/gear/resist...ce/?scope=anon
https://www.bicyclerollingresistance...-tr-comparison
Additionally, in all of Bicycle Roiling Resistance's road tire tests resistance is reduced with increasing pressure. I'm not a subscriber and some of the results are shielded but that's true from their extra high to ultra high pressure categories.
Thoughts?
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One of my conundrums: I feel there is conflicting evidence for lower tire pressures being beneficial. These two sources seem to indicate that higher pressures create less rolling resistance.
https://www.velonews.com/gear/resist...ce/?scope=anon
https://www.bicyclerollingresistance...-tr-comparison
Additionally, in all of Bicycle Roiling Resistance's road tire tests resistance is reduced with increasing pressure. I'm not a subscriber and some of the results are shielded but that's true from their extra high to ultra high pressure categories.
Thoughts?
https://www.velonews.com/gear/resist...ce/?scope=anon
https://www.bicyclerollingresistance...-tr-comparison
Additionally, in all of Bicycle Roiling Resistance's road tire tests resistance is reduced with increasing pressure. I'm not a subscriber and some of the results are shielded but that's true from their extra high to ultra high pressure categories.
Thoughts?
Bikes don't ride on perfectly smooth surfaces. Recommended real-world pressures are designed to give the tire about 15% deflection when loaded, which is enough spring to absorb minor bumps and not force the entire suspensionless road bike have to go up and over every pebble, and subsequently decelerate from having to do so.
That's just the rolling resistance aspect, ignoring braking and cornering traction.
Riding on an Olympic track? By all means, increase your pressure over road recommendations.
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One of my conundrums: I feel there is conflicting evidence for lower tire pressures being beneficial. These two sources seem to indicate that higher pressures create less rolling resistance.
https://www.velonews.com/gear/resist...ce/?scope=anon
https://www.bicyclerollingresistance...-tr-comparison
Additionally, in all of Bicycle Roiling Resistance's road tire tests resistance is reduced with increasing pressure. I'm not a subscriber and some of the results are shielded but that's true from their extra high to ultra high pressure categories.
Thoughts?
https://www.velonews.com/gear/resist...ce/?scope=anon
https://www.bicyclerollingresistance...-tr-comparison
Additionally, in all of Bicycle Roiling Resistance's road tire tests resistance is reduced with increasing pressure. I'm not a subscriber and some of the results are shielded but that's true from their extra high to ultra high pressure categories.
Thoughts?
Maybe SMD has unusually high quality, clean streets. Like those of a velodrome or the surface of a swimming pool. In which case, he might be on to something. For the rest of us, the balance between tire load, width (height, really) and pressure is a moving target based on ever changing use cases.
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#66
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Rolling resistance is lower on smooth surfaces at higher pressure.
Bikes don't ride on perfectly smooth surfaces. Recommended real-world pressures are designed to give the tire about 15% deflection when loaded, which is enough spring to absorb minor bumps and not force the entire suspensionless road bike have to go up and over every pebble, and subsequently decelerate from having to do so.
That's just the rolling resistance aspect, ignoring braking and cornering traction.
Riding on an Olympic track? By all means, increase your pressure over road recommendations.
Bikes don't ride on perfectly smooth surfaces. Recommended real-world pressures are designed to give the tire about 15% deflection when loaded, which is enough spring to absorb minor bumps and not force the entire suspensionless road bike have to go up and over every pebble, and subsequently decelerate from having to do so.
That's just the rolling resistance aspect, ignoring braking and cornering traction.
Riding on an Olympic track? By all means, increase your pressure over road recommendations.
True. And solid freight train rolling stock has the lowest rolling resistance of all. The whole discussion is about finding the balance between competing nominals.
Maybe SMD has unusually high quality, clean streets. Like those of a velodrome or the surface of a swimming pool. In which case, he might be on to something. For the rest of us, the balance between tire load, width (height, really) and pressure is a moving target based on ever changing use cases.
Maybe SMD has unusually high quality, clean streets. Like those of a velodrome or the surface of a swimming pool. In which case, he might be on to something. For the rest of us, the balance between tire load, width (height, really) and pressure is a moving target based on ever changing use cases.
I'm not really sure why I care. I don't even attempt to ride fast anymore and at my speeds the effect is probably so small it is negligible on my shorter rides.
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I understand what both of you are saying. I've read about the 15% deflection and the idea that the tire conforms to the irregularities in the road rather than lifting the entire load. Yet, all referenced tests were on a diamond plate surface which is not smooth. In fact, the Outside article chose it to simulate asphalt roads. In these controlled studies on a irregular surface, higher pressure was less resistance. I need to dig back to some of the counter articles to study their methodology.
I'm not really sure why I care. I don't even attempt to ride fast anymore and at my speeds the effect is probably so small it is negligible on my shorter rides.
I'm not really sure why I care. I don't even attempt to ride fast anymore and at my speeds the effect is probably so small it is negligible on my shorter rides.
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#68
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I understand what both of you are saying. I've read about the 15% deflection and the idea that the tire conforms to the irregularities in the road rather than lifting the entire load. Yet, all referenced tests were on a diamond plate surface which is not smooth. In fact, the Outside article chose it to simulate asphalt roads. In these controlled studies on a irregular surface, higher pressure was less resistance. I need to dig back to some of the counter articles to study their methodology.
I'm not really sure why I care. I don't even attempt to ride fast anymore and at my speeds the effect is probably so small it is negligible on my shorter rides.
I'm not really sure why I care. I don't even attempt to ride fast anymore and at my speeds the effect is probably so small it is negligible on my shorter rides.
https://silca.cc/blogs/silca/part-4b...-and-impedance
In short: the drum doesn't simulate the rider and so the drum will keep showing lower rolling resistance at higher pressures even with an uneven drum surface.
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This article explains it pretty well
https://silca.cc/blogs/silca/part-4b...-and-impedance
In short: the drum doesn't simulate the rider and so the drum will keep showing lower rolling resistance at higher pressures even with an uneven drum surface.
https://silca.cc/blogs/silca/part-4b...-and-impedance
In short: the drum doesn't simulate the rider and so the drum will keep showing lower rolling resistance at higher pressures even with an uneven drum surface.
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And again--anyone who thinks high-pressure pneumatic tires feel anything even remotely the same as solid tires must have no experience with either.
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at 280lbs even I don't run my tires that high anymore, 35/30, all about tires conforming to the surface. Interesting to me is that I used to run 26x1.95 at 50psi in my 20s and dented so many wheels, had lousy times in races and really poor handling ability. Didn't mtb in my 30s except on the cross bike from time to time. Picked up a modern 29er running 2.25 and not only do I have faster times but I ride much more technical terrain and have yet to dent a rim. I find MTBing much more enjoyable now.
#73
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Maybe you don't understand how this works. In post 38 Kontact said that my tires were slow. He brought up the concept of speed. I responded--as I am allowed, and how discussion goes--in post 39, by simply stating they weren't slow--and that I also liked the road feel. I also provided a quote to back up that assertion, which stated that narrow tires--which I use--aren't "slow."
And again--anyone who thinks high-pressure pneumatic tires feel anything even remotely the same as solid tires must have no experience with either.
And again--anyone who thinks high-pressure pneumatic tires feel anything even remotely the same as solid tires must have no experience with either.
All that being said, you'd likely be much faster below 100psi. But as you prefer to be slow, I'm sure that doesn't matter to you.
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I wonder what would happen if everyone on a group ride discussed tire pressure and chain lube before starting out.
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