comfortable inflation vs. manufacturers recommended range
#51
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How would a tube "push the tire out from the rim"?
The tire is the pressure vessel with high tensile stiffness, not the inner tube. Inner tubes don't really have an engineered PSI threshold, and if they're not surrounded by a tire, they're not even capable of containing much pressure: they just get bigger and bigger like a party balloon as more air is added until the rubber tears from being stretched too far.
The tire is the pressure vessel with high tensile stiffness, not the inner tube. Inner tubes don't really have an engineered PSI threshold, and if they're not surrounded by a tire, they're not even capable of containing much pressure: they just get bigger and bigger like a party balloon as more air is added until the rubber tears from being stretched too far.
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#52
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I haven’t seen that. The Silca calculator actually has the user select from various standard bike geometries (TT, road, gravel and MTB) with different F/R percentages and produces separate recommendations for front and rear. I’d be cautious about lowering the front too much as there is still braking to be done and out of the saddle work, both of which put more weight on the front.
Otto
Otto
Clearly, you have not measured and do not believe me. This is what Zinn says
I’m convinced that anybody who says the weight distribution on a road bike should be 55 percent on the rear wheel and 45 percent on the front (or 50/50, or anything in the realm below 60 percent on the rear wheel) never actually measured it.
Don’t be surprised if it comes out 70/30.
#53
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Like, if you take a "25mm" inner tube outside of a tire and start pumping it up, it will happily get far larger than a 25mm tire even when its internal pressure is barely higher than that of the ambient air. The reason it doesn't get huge when it's inside of a 25mm tire is that it's being constrained by the tire.
#54
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The problem that I have with the "use a small differential to avoid front tire collapse" reasoning is that it doesn't seem like a logical solution to the proposed issue. Many proponents of the strategy will recommend dropping from 93r/89f to 75r/72f (or whatever) if a ride contains some rough sections, but hard braking or cornering on a stretch of good pavement in the latter case doesn't put less stress on the tire than in the former case.
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The problem that I have with the "use a small differential to avoid front tire collapse" reasoning is that it doesn't seem like a logical solution to the proposed issue. Many proponents of the strategy will recommend dropping from 93r/89f to 75r/72f (or whatever) if a ride contains some rough sections, but hard braking or cornering on a stretch of good pavement in the latter case doesn't put less stress on the tire than in the former case.
Proper tire pressure depends entirely on the road surface to optimize the suspension effects needed for the road surface. As long as you are above recommended minimums, there is no problem. And, just to sum up....I pick the highest pressure that gets me good comfort on the roads that day. Today, it was one pressure and tomorrow's nice roads will be a different pressure and always lower pressure on the front tire on my road bike
#56
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I wasn't disagreeing with what you wrote. I was criticizing some of the arguments that get made against significant front-rear pressure differences.
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I was just noting they use figures (slightly) different from 50/50.
For my way of looking at it, it’s an empirical compromise and I try to run the lowest pressure that avoids issues while being as comfortable as possible. I decide that by connecting measured pressures with how the ride goes.
For my 700x32 bike, Silca recommends 56 front/59 rear. With my current tires, I typically run 55/58 using my Meiser gauge. No need for more in the rear, but much less and I don’t like the feel. Same in the front… no need for more but much less and I don’t like it. I did a ride Sunday where it felt squishy when I was standing and came home to measure 52 psi.
Since you asked, I did quick static measurements and show that it will typically run at least 70 front/30 rear when I am leaning over the bars and standing, which happens dozens of times in a typical ride. That’s why I notice it if the front is below 55 psi.
Otto
For my way of looking at it, it’s an empirical compromise and I try to run the lowest pressure that avoids issues while being as comfortable as possible. I decide that by connecting measured pressures with how the ride goes.
For my 700x32 bike, Silca recommends 56 front/59 rear. With my current tires, I typically run 55/58 using my Meiser gauge. No need for more in the rear, but much less and I don’t like the feel. Same in the front… no need for more but much less and I don’t like it. I did a ride Sunday where it felt squishy when I was standing and came home to measure 52 psi.
Since you asked, I did quick static measurements and show that it will typically run at least 70 front/30 rear when I am leaning over the bars and standing, which happens dozens of times in a typical ride. That’s why I notice it if the front is below 55 psi.
Otto
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I was just noting they use figures (slightly) different from 50/50.
For my way of looking at it, it’s an empirical compromise and I try to run the lowest pressure that avoids issues while being as comfortable as possible. I decide that by connecting measured pressures with how the ride goes.
For my 700x32 bike, Silca recommends 56 front/59 rear. With my current tires, I typically run 55/58 using my Meiser gauge. No need for more in the rear, but much less and I don’t like the feel. Same in the front… no need for more but much less and I don’t like it. I did a ride Sunday where it felt squishy when I was standing and came home to measure 52 psi.
Since you asked, I did quick static measurements and show that it will typically run at least 70 front/30 rear when I am leaning over the bars and standing, which happens dozens of times in a typical ride. That’s why I notice it if the front is below 55 psi.
Otto
For my way of looking at it, it’s an empirical compromise and I try to run the lowest pressure that avoids issues while being as comfortable as possible. I decide that by connecting measured pressures with how the ride goes.
For my 700x32 bike, Silca recommends 56 front/59 rear. With my current tires, I typically run 55/58 using my Meiser gauge. No need for more in the rear, but much less and I don’t like the feel. Same in the front… no need for more but much less and I don’t like it. I did a ride Sunday where it felt squishy when I was standing and came home to measure 52 psi.
Since you asked, I did quick static measurements and show that it will typically run at least 70 front/30 rear when I am leaning over the bars and standing, which happens dozens of times in a typical ride. That’s why I notice it if the front is below 55 psi.
Otto