I have not been able to find any data with regard to “the difference between carbon sole shoes and non carbon soles.” Specifically regarding power transfer or lack thereof. Anyone have data? (no opinions please)
I never thought carbon soles were touted as providing better power transfer. They simply give a stiff sole with less weight.
The advantage of carbon is that you get a stiff AND light shoe. Non-carbon soles can be stiff too, it just takes more material and therefore more weight.
really? it seems a lot of shoe manufacturers seem to tout power transfer as a selling point. what’s the point of having a stiff sole? (this is a real question, sorry i don’t know)
stiff=efficient
from a mechanical perspective, any energy spent bending the shoe is energy not moving the crank
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I never thought carbon soles were touted as providing better power transfer. They simply give a stiff sole with less weight.
I’ve always had a hard time understanding how stiffness matters in a cycling shoe. It seems like one would not need any sole behind the cleat at all, if one could keep the shoe on the foot during the pedal stroke. It’s not like a running shoe that needs to flex during ground contact.
Can you or anyone else explain it to me? Use small words.
"from a mechanical perspective, any energy spent bending the shoe is energy not moving the crank "
How do you bend the shoe when the pedal axle is a pivot? Wouldn’t the vertical force under your heel be pretty much zero at all times?
How do you bend the shoe when the pedal axle is a pivot? Wouldn’t the vertical force under your heel be pretty much zero at all times?
some people mount their pedals in the middle of the foot instead of under the ball, so they are applying pressure fore and aft of the pedal spindle, requiring a stiff coupling (the shoe) to efficiently transfer that pressure.
if the pedal was exactly under the ball of your foot I don’t think it would matter as much
important questions:
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where does that energy go that you used to bend the shoe when the shoe bends back?
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of the energy that isn’t going right back to the pedal, but is instead lost to heating up the shoe, how much IS that? is is event 1 watt?
How do you bend the shoe when the pedal axle is a pivot? Wouldn’t the vertical force under your heel be pretty much zero at all times?
some people mount their pedals in the middle of the foot instead of under the ball, so they are applying pressure fore and aft of the pedal spindle, requiring a stiff coupling (the shoe) to efficiently transfer that pressure.
if the pedal was exactly under the ball of your foot I don’t think it would matter as much
important questions:
-
where does that energy go that you used to bend the shoe when the shoe bends back?
-
of the energy that isn’t going right back to the pedal, but is instead lost to heating up the shoe, how much IS that? is is event 1 watt?
-
that depends on the modulus of elasticity of the shoe. some of it is returned, much less is lost to heat, and an even smaller portion of it might permanently deform the shoe
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no, probably less than 1 watt unless the shoe is made of very bendy fiberglass and you are pedaling like cancellara
- no, probably less than 1 watt unless the shoe is made of very bendy fiberglass and you are pedaling like cancellara
then imma suggest this is not worth worrying about
=)
yeah, but this is slowtwitch.
what would we talk about if we didn’t argue over things like what kind of tape to put on the vents of a helmet to save 1/10th second during the bike leg of an ironman?
I never thought carbon soles were touted as providing better power transfer. They simply give a stiff sole with less weight.
I’ve always had a hard time understanding how stiffness matters in a cycling shoe. It seems like one would not need any sole behind the cleat at all, if one could keep the shoe on the foot during the pedal stroke. It’s not like a running shoe that needs to flex during ground contact.
Can you or anyone else explain it to me? Use small words.
Ken! You are smart, so you are obviously using the Socratic method here.
I do agree with the point that I believe you are trying to make. And in fact, my comment that you quoted pretty much was in line with that. My point being that carbon soles aren’t better than any other material with the exception that they are lighter.
Now on the subject of stiff soles and ‘power transfer’. All I can imagine is that if you had a shoe like a Vibram FF with a cleat on the bottom and only that area around the cleat was covered with a ‘stiff’ area, that it would hurt your foot eventually because that part of the shoe would push in to your foot unless you maintained a permanently plantarflexed foot. I think it’s more for comfort than power transfer although that misconception exists.
For instance, I did a lot of cycling in my youth using toe cages and running shoes. The pedal edge under the ball of my foot would dig in a bit and create pressure pain on my foot after a few hours.
“Stiff” does not tell me what I want to know. The only benefit of stiff (in my opinion) would be better power transfer to the pedal. The weight of the new specialized triathlon shoes are separated by only 10 grams which to me is insignificant versus the $75 price difference. Therefore, if there is no statistical difference in efficiency, I will save my $75.
So I will bring it back to the original question:
Does anyone have any data (solid numbers, not opinions) with regard to the performance of carbon soles and non carbon soles?
I found some data for us thanks to my new friend Karl at USAT. 2 studies below. The first suggests that carbon is significantly stiffer than nylon, but only a little stiffer than carbon/nylon mix. The 2nd study shows a trade off by suggesting that carbon sole shoes could further increase an existing foot or lower leg condition. Good info in my mind in that it shows the pro’s and cons statistically.
Carbon composites help cycling shoes transfer power from leg to pedal
BYLINE: Jordana Bieze Foster
SECTION: IN STRIDE WITH SPORTS MEDICINE; Pg. 11
LENGTH: 177 words
HIGHLIGHT: Research from Korea confirms that, as cycling shoe manufacturers claim, carbon composite outsole materials do facilitate more efficient energy transfer from foot to pedal.
"Investigators from Inje University obtained pressure measurements for a 28-year-old male cyclist pedaling at 90 rpm, then applied the calculated loading force of 660 N to a finite element analysis of three outsole constructions: all carbon composite, nylon outsole with carbon composite insert, and all nylon.
They found significantly greater levels of maximum forefoot stress corresponding to significantly less displacement at the heel in the two constructions with the carbon composite (see table).** Interestingly, reducing the amount of carbon composite by 50% decreased maximum forefoot stress by only 10%.**
The results were presented in August at the joint meeting of the ISB and ASB.
MAXIMUM FOREFOOT STRESS
Carbon : 33.773 MPa
Carbon/nylon : 33.488 MPa
Nylon : 1.9 MPa
MAXIMUM HEEL DISPLACEMENT
Carbon : 0.436 mm
Carbon/nylon : 0.633 mm
Nylon : 19.585 mm
The effects of cycling shoe stiffness on forefoot pressure.
Authors: Jarboe, N.E. / Quesada, P.M. Pmques01@louisville.eduSource: Foot & Ankle International Oct 2003: Vol. 24 Issue 10. p. 784-788 5p.Publisher: http://www.aofas.org/
Abstract:Plantar pressure data were recorded in two different shoe types to determine the effect of cycling shoe stiffness on peak plantar forefoot pressure in cyclists. Two pairs of shoes of the same size and manufacturer, identical except for outsole material and stiffness, were tested. Shoe stiffness measurements were collected under controlled conditions and in two different configurations using a dynamic hydraulic tensile testing machine. Measurements of plantar pressure were done using Pedar capacitive-based sensor insoles while subjects pedaled in a seated position at a controlled power output. Power output was set at a constant value of 400 W across all subjects by a magnetic resistance trainer unit. The pressure distribution in carbon-fiber-composite shoes during cycling was compared to cycling shoes made with plastic soles. Carbon fiber shoes presented stiffness values 42 % and 550 % higher than plastic shoes in longitudinal bending and three-point bending, respectively. The shoes made with carbon fiber produced peak plantar pressures 18 % higher than those of plastic design (121 kPa vs. 103 kPa, p = .005). Competitive or professional cyclists suffering from metatarsalgia or ischemia should be especially careful when using carbon fiber cycling shoes because the shoes increase peak plantar pressure, which may aggravate these foot conditions.
Tests have always had trouble showing any measurable power loss due to different stiffness of soles. Several tests were done between flexier touring shoes, plastic soles and wooden ones (this is pre CF).
I have some Sidis with plastic soles and some with CF soles. The CF is lighter and stiffer, but it’s probably not possible to measure any wattage improvement.
One factor that you all missed…how THIN is the sole? Companies like Time for instance have made their claim to fame by offering a lower “Bio-Position” as they put it. The closer you are to the pedal axle center the more efficient you are (or so they say). I do know that if I have Look pedals on my bike I need to raise my seat about a centimeter as opposed to my Time. This can be seen even more so with the Sidemount Pedal http://www.sidemountpedal.com/
“Stiff” does not tell me what I want to know. The only benefit of stiff (in my opinion) would be better power transfer to the pedal. The weight of the new specialized triathlon shoes are separated by only 10 grams which to me is insignificant versus the $75 price difference. Therefore, if there is no statistical difference in efficiency, I will save my $75.
So I will bring it back to the original question:
Does anyone have any data (solid numbers, not opinions) with regard to the performance of carbon soles and non carbon soles?
it might not be what you’re looking for, but information on weight and price *are *data. They’re just data about weight and price, not efficiency.
The price part obviously has nothing to do with performance. Does the weight? I suspect that weight of shoes would be less significant than, say, weight of rims or tires; but since you are moving them, they’d be more significant that the weight of, say, the frame or the seat.
One factor that you all missed…how THIN is the sole? Companies like Time for instance have made their claim to fame by offering a lower “Bio-Position” as they put it. The closer you are to the pedal axle center the more efficient you are (or so they say). I do know that if I have Look pedals on my bike I need to raise my seat about a centimeter as opposed to my Time. This can be seen even more so with the Sidemount Pedal http://www.sidemountpedal.com/
Wouldn’t that effect the q-value? Looks to me the pedals are further out than “normal” pedals. But I’m no expert, just wondering.
Almost pure opinion coming up, so take it or leave it:
The reason very little data is available is that the data won’t show a statistically significant difference. If the data was there, the marketers of expensive shoes would use it. If the data is not there, the marketers appeal to your sense of logic, even if the logic does not work.
Stiffer must be better right? But what is actually going to flex on the sole of the shoe during the pushing anyway?
If you have the cleat mounted under the arch of your foot, only then will stiffness in that area will be important to transfer the power from the ball and maybe heel of your foot to the area where the cleat is.
If your cleat is farther forward so that it is under the ball of your foot, almost nothing will flex on any shoe, since the power would be applied from your foot primarily at that point. You could wear very flexible shoes with no power loss. In fact very flexible would be better as you would waste less energy in the normal flexing of your foot.