Wheelset upgrade questions
#27
Non omnino gravis
I've no idea what year the OP has, but even the 2020 Allez (no suffix, just Allez) comes equipped with 8-speed Claris, and Axis Sport wheels. I can't find anything about that particular wheelset. The disc version of the Axis has a 10/11 speed freehub, so it's relatively safe to assume it's the same freehub on the non-disc wheelset. Is anyone even making new OEM wheels without 10/11 freehubs?
#28
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The funny thing is, you're probably faster with the tires under inflated- as soft as you can get away with.
AFAK wearing out the tires before replacing them, you probably weren't thinking that you had to wear out the wheels before getting new ones,
so the same could be for the tires.
#29
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The funny thing is, you're probably faster with the tires under inflated- as soft as you can get away with.
AFAK wearing out the tires before replacing them, you probably weren't thinking that you had to wear out the wheels before getting new ones,
so the same could be for the tires.
AFAK wearing out the tires before replacing them, you probably weren't thinking that you had to wear out the wheels before getting new ones,
so the same could be for the tires.
Higher pressures are faster, except they make you bounce. So you want the highest pressure that allows the tyre to suspend you properly, assuming rolling resistance is your priority.
+1 bugger waiting until the tyres are worn.
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#30
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I've no idea what year the OP has, but even the 2020 Allez (no suffix, just Allez) comes equipped with 8-speed Claris, and Axis Sport wheels. I can't find anything about that particular wheelset. The disc version of the Axis has a 10/11 speed freehub, so it's relatively safe to assume it's the same freehub on the non-disc wheelset. Is anyone even making new OEM wheels without 10/11 freehubs?
#31
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Optimal tyre pressure is around whatever makes the loaded tyre sag 15% - higher for smooth surfaces, lower for rough surfaces. You might want to allow a bit more in the front to account for weight transfer when braking.
Higher pressures are faster, except they make you bounce. So you want the highest pressure that allows the tyre to suspend you properly, assuming rolling resistance is your priority.
+1 bugger waiting until the tyres are worn.
Higher pressures are faster, except they make you bounce. So you want the highest pressure that allows the tyre to suspend you properly, assuming rolling resistance is your priority.
+1 bugger waiting until the tyres are worn.
I think this has been dis-proven and for normal road surfaces, lower pressure is faster pretty much to the limits of snake bites, rim damage, and squirmy handling in turns.
So the reverse- you want the lowest pressure that allows the tire to....
#32
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If that was true, perhaps you should tell track riders to stop running 160psi.
The old wisdom about rolling resistance was wrong because the tires being too hard meant forward motion was being translated into vertical motion of the bike and rider.
But the idea behind it was based on the very real drag of hysteresis from the tyres, which hasn't disappeared just because we suddenly want the tyres to do suspension. It's a matter of balancing the two factors, which depends on the quality of the surface you're riding. This commonly translates to around 10-15psi less than the old recommendations, which IIRC more or less agrees with the 15% sag rule.
The old wisdom about rolling resistance was wrong because the tires being too hard meant forward motion was being translated into vertical motion of the bike and rider.
But the idea behind it was based on the very real drag of hysteresis from the tyres, which hasn't disappeared just because we suddenly want the tyres to do suspension. It's a matter of balancing the two factors, which depends on the quality of the surface you're riding. This commonly translates to around 10-15psi less than the old recommendations, which IIRC more or less agrees with the 15% sag rule.
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Sheldon Brown's bike info ~~~ Park Tools repair help
Half-step triple, using double gear ~~~ 6400 STI rebuild walkthrough ~~~ Want 8/9/10s @126mm OLD? OCR. ~~~ Shimano cassette body overhaul ~~~ Ergopower Escape wear repair ~~~ PSA: drivetrain wear
List of US/Canada bike co-ops ~~~ Global list
Sheldon Brown's bike info ~~~ Park Tools repair help
Half-step triple, using double gear ~~~ 6400 STI rebuild walkthrough ~~~ Want 8/9/10s @126mm OLD? OCR. ~~~ Shimano cassette body overhaul ~~~ Ergopower Escape wear repair ~~~ PSA: drivetrain wear
List of US/Canada bike co-ops ~~~ Global list
#33
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Track riders enjoy a very smooth surface, the tire doesn't have to flex around any texture like on the road. Even the newest and best pavement - which is rare - is nothing like a polished track.
#34
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Um, yeah, that's why you use about half track pressure on the road, just like I said. But @woodcraft here seems to believe lower pressure is plain faster, with the only downside being pinch flats and squirm.
Hysteresis is still a thing. The optimal pressure is the highest amount that still absorbs most of the irregularities that would lift the wheel if the tyre was hard.
The other thing that's changed in our awareness is that we know a wider tyre has a faster contact patch because it's not as long, so we're using 25s and 28s instead of 23s and 25s, thus using the lower pressures appropriate for wider tyres.
But it's all about striking a compromise; it's not like wide and soft is the be-all and end-all. Tyres weigh something, and have to push a hole through the air, and they have to absorb energy when they deform, just like we've always known.
Hysteresis is still a thing. The optimal pressure is the highest amount that still absorbs most of the irregularities that would lift the wheel if the tyre was hard.
The other thing that's changed in our awareness is that we know a wider tyre has a faster contact patch because it's not as long, so we're using 25s and 28s instead of 23s and 25s, thus using the lower pressures appropriate for wider tyres.
But it's all about striking a compromise; it's not like wide and soft is the be-all and end-all. Tyres weigh something, and have to push a hole through the air, and they have to absorb energy when they deform, just like we've always known.
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Sheldon Brown's bike info ~~~ Park Tools repair help
Half-step triple, using double gear ~~~ 6400 STI rebuild walkthrough ~~~ Want 8/9/10s @126mm OLD? OCR. ~~~ Shimano cassette body overhaul ~~~ Ergopower Escape wear repair ~~~ PSA: drivetrain wear
List of US/Canada bike co-ops ~~~ Global list
Sheldon Brown's bike info ~~~ Park Tools repair help
Half-step triple, using double gear ~~~ 6400 STI rebuild walkthrough ~~~ Want 8/9/10s @126mm OLD? OCR. ~~~ Shimano cassette body overhaul ~~~ Ergopower Escape wear repair ~~~ PSA: drivetrain wear
List of US/Canada bike co-ops ~~~ Global list
Last edited by Kimmo; 08-11-19 at 02:32 AM.
#35
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That's why I ride 28s and not 280s. 🙂
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I think I've overstated my case- I ride tubulars which perform well to lower pressures,
but I still think that the 15% drop rule is from the old, harder-is-faster era.
https://janheine.wordpress.com/2019/...ure-is-faster/
In this article, fig.1 shows testing on super-smooth asphalt. Results would likely skew to lower pressures on regular pavement, and rider weight is not addressed but would no doubt change results in either direction.
but I still think that the 15% drop rule is from the old, harder-is-faster era.
https://janheine.wordpress.com/2019/...ure-is-faster/
In this article, fig.1 shows testing on super-smooth asphalt. Results would likely skew to lower pressures on regular pavement, and rider weight is not addressed but would no doubt change results in either direction.
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I put (msrp) $1700 on my (msrp) $1800 bike, and I don't regret the decision. If you're gonna shell out though, may as well go tubeless, IMO. Also, search cl and ebay for deals.