So I ditched 85g butyl for 35g TPU inner tubes
#126
Senior Member
I'm well above the scatter graph of pro cyclists, but still liked (past tense, but still a little) to play a weight weenie game within a modest budget. Still like lightweight-ish bikes.
By the way, I just bought a set of latex tubes. Why not TPU? I dunno, it was an impulse buy when a "sale" popped up somewhere. I've always used lightweight and undersized butyl tubes, mainly because the undersized ones are easier to install. Add lightweight, and they're more compact to fit the spare in my saddle bag. As a change from my past attitude, I bought these tubes, not for the weight savings, but I wanted to see if they made any perceptible difference in ride quality with the good quality tires I ride.
By the way, I just bought a set of latex tubes. Why not TPU? I dunno, it was an impulse buy when a "sale" popped up somewhere. I've always used lightweight and undersized butyl tubes, mainly because the undersized ones are easier to install. Add lightweight, and they're more compact to fit the spare in my saddle bag. As a change from my past attitude, I bought these tubes, not for the weight savings, but I wanted to see if they made any perceptible difference in ride quality with the good quality tires I ride.
Last edited by Camilo; 05-20-24 at 12:48 PM.
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#127
Senior Member
Join Date: Aug 2019
Location: Québec, Canada
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At 185cm & 76kg, I'm definitively too heavy to be a pro cyclist . Lightest I've been is last November at 75kg and I was starting to look like a skeleton. Definitively not my healthy weight.
#128
pan y agua
Join Date: Aug 2005
Location: Jacksonville
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way too big of a generalization. If we’re talking about body weight, you have to consider surface to volume ratio. As people get heavier, their surface area doesn’t increase linearly with weight. Thus, comparatively larger riders tend to have better surface to power ratios than little climber guys. ( assuming that the larger rider produces more power from being bigger, and isn’t just fat.)
Thus a bigger racer like Fabio Castelli, can be dominant on a flat tt course with a great power to surface ratio, but not an elite climber because his power to weight ratio s lower than the elite little climbers.
In other words, a heavier rider can be more aero, at least in relation to their power, Than a smaller rider, if the extra weight correlates with more power.
Thus a bigger racer like Fabio Castelli, can be dominant on a flat tt course with a great power to surface ratio, but not an elite climber because his power to weight ratio s lower than the elite little climbers.
In other words, a heavier rider can be more aero, at least in relation to their power, Than a smaller rider, if the extra weight correlates with more power.
__________________
You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.
You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.
#129
Senior Member
way too big of a generalization. If we’re talking about body weight, you have to consider surface to volume ratio. As people get heavier, their surface area doesn’t increase linearly with weight. Thus, comparatively larger riders tend to have better surface to power ratios than little climber guys. ( assuming that the larger rider produces more power from being bigger, and isn’t just fat.)
Thus a bigger racer like Fabio Castelli, can be dominant on a flat tt course with a great power to surface ratio, but not an elite climber because his power to weight ratio s lower than the elite little climbers.
In other words, a heavier rider can be more aero, at least in relation to their power, Than a smaller rider, if the extra weight correlates with more power.
Thus a bigger racer like Fabio Castelli, can be dominant on a flat tt course with a great power to surface ratio, but not an elite climber because his power to weight ratio s lower than the elite little climbers.
In other words, a heavier rider can be more aero, at least in relation to their power, Than a smaller rider, if the extra weight correlates with more power.
The generalization which you quoted is perfectly valid.
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#130
#131
Senior Member
#132
pan y agua
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Location: Jacksonville
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As you scale people up, their surface area doesn’t go up linearly with weight. So if the heavier rider is stronger, they’re going to be faster in a flat tt, hence riders like Cancellera, who was a great time trialist, but not an elite climber.
__________________
You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.
You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.
#133
pan y agua
Join Date: Aug 2005
Location: Jacksonville
Posts: 31,475
Bikes: Willier Zero 7; Merlin Extralight; Calfee Dragonfly tandem, Calfee Adventure tandem; Cervelo P2; Motebecane Ti Fly 29er; Motebecanne Phantom Cross; Schwinn Paramount Track bike
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Again in absolute terms, the more you weigh, the more aerodynamic drag you have is correct.
However, coasting downhill ( which I believe is where this started), the larger rider’s added mass will more than offset the increased drag because the bigger riders proportionate increase in weight is less than their increase in surface volume.
And if the the large rider has a proportionately higher power output than a smaller rider, the larger rider will be faster on a flat tt, because they have a comparitively smaller surface area in relation their respective weights.
It’s why I can win Tt’s and get dropped on climbs by people I can beat in a tt.
__________________
You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.
You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.
#134
they’re relatively more aero in relation to their power output, i.e. watts/surface area tends to be better for a larger rider than a smaller equally fit rider, while the smaller rider is likely to have watts/kg.
As you scale people up, their surface area doesn’t go up linearly with weight. So if the heavier rider is stronger, they’re going to be faster in a flat tt, hence riders like Cancellera, who was a great time trialist, but not an elite climber.
As you scale people up, their surface area doesn’t go up linearly with weight. So if the heavier rider is stronger, they’re going to be faster in a flat tt, hence riders like Cancellera, who was a great time trialist, but not an elite climber.
#135
Senior Member
It seems like you dragged this off on a tangent in an attempt to impress us all with your vast knowledge; Next time you feel a need to do that, please leave me out of it.
Last edited by Koyote; 05-22-24 at 03:07 PM.