On 8/11/2020 11:28 PM, jbeattie wrote:
On Tuesday, August 11, 2020 at 6:03:46 PM UTC-7, Frank Krygowski wrote:
On 8/11/2020 6:05 PM, jbeattie wrote:

I certainly pulled up or across the pedal when track racing, and if I pulled out, it could be catastrophic -- and thus double straps and later clipless (some racers used clipless and straps). Foot retention is important when sprinting and climbing out of the saddle. https://www.tandfonline.com/doi/full...0.2020.1769201

It's a shame they didn't test stiff soled cycling shoes with toe clips.
For a long time those were the default choice for avid cyclists. They're
still my choice for long rides.

But I'll point out, that paper (apparently) did not measure efficiency.
The power improvements were huge (9.7 ± 8.7% power gain by adding toe
clips to soft shoes, and 16.6 ± 10.2% gain with rigid shoes and
clipless). On a five percent grade, that corresponds to a very
noticeable increase in speed. If those gains were due to lack of
efficiency of soft soles, those soles must have been soaking up a hell
of a lot of power. That means they should get very hot.

We can discuss this, but I suspect a lot of the gains measured were due
to the "red bikes are faster" effect. Testers were probably
preconditioned to think toe clips help a lot, and REAL cycling shoes and
clipless are what professionals use. That's a recipe for a powerful placebo.

If not that, then what made the power difference? Where would the power
have been previously lost? We should be able to talk about that in detail.

And shoes can make a big difference. I remember going from Detto, Vittoria or Italia (they all blended together) bicycling/bowling shoes of yore with little steel stiffeners and nail on cleats to Duegis with wood soles and bolt-on plastic cleats. https://www.classicsteelbikes.com/wp...-1-600x400.jpg That was huge -- like going from Michelin 50s to Vittoria CGs (I never rode silks). That was probably the single biggest component improvement I ever had.

Again, we should be able to analyze the exact source of the improvement.
The shoes are not a source of power; they are a simple device for
transmitting power from your foot to the pedal.

I don't doubt that some changes allow better biomechanics and thus
better power output. But it's hard for me to see how shoes do that.


A couple of things: (1) your ankle is not a spring, dropping as the sole flexes. Old cycling shoes were really like bowling shoes and not very stiff. (2) Deeper, more secure cleats -- for better or worse. It was not a subtle change for me at all. Others agree: http://stevetilford.com/2016/05/26/cycling-shoes-2/ YMMV.

I'm not surprised that there are people who rhapsodize about shoes. And
I know that certain shoes are more or less comfortable for certain
riders, some shoes have better closure systems, etc. But to return to
_technical_ discussion about power transfer:

Again, the paper you linked could have tested stiff soled shoes with toe
clips. Unfortunately it didn't.

And it's true that "stiff" isn't a binary condition. But aside from
commuting or utility riding, all the cycling shoes I've used (since Bata
Bikers came on the scene) have seemed pretty stiff to me. Not as stiff
as wooden soles, but then, nobody here has identified a mechanism for
power loss through a sole that's a little less stiff.

Thought experiment (since you mention springs): Place a spring with a
high stiffness (say, 100 pounds per inch) on a bike pedal. Place a ten
pound weight on that spring. It will sag 1/10 inch. What's the force on
the pedal?

Repeat with a spring that's less stiff (say, 50 pounds per inch). Place
the same ten pound weight on that spring. It will sag 2/10 inch. What's
the force on that pedal?

The answer is the same in both cases: Pedal force is ten pounds.


--
- Frank Krygowski