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heres a question: Pedal manufacturer's claim that(26 posts)

heres a question: Pedal manufacturer's claim thatraler
Aug 24, 2001 7:41 AM
the smaller the distance from the pedal axle to the shoe sole, the greater the rider's efficiency and power output.

Speedplay, Coombe, and I think Shimano make this statement.

It seems like no matter what the distance your still going to be turning the same crank, same circle.

The only thing I can think of is that one's power through the bottom of the stroke, where you pull your foot backwards, might be compromised with a slightly larger distance here. Is this what they are referring to with their claim?
I'm no engineer, but...jtolleson
Aug 24, 2001 8:08 AM
It seems to me that extra distance from the sole to the pedal spindle means you are turning an incrementally larger circle and thus wasting enery.
I AM an engineer:alex the engineer
Aug 24, 2001 8:32 AM
you will have the same size circle, except that it will be transposed up, by the distance measured. However, if you are a large distance from the pedal axle, you may tend to tip over, and spend a bit of energy overcoming this tendancy to tilt your foot. Other than that, I don't have a clue what they are basing their assumption on.
I AM an engineer:nova
Aug 24, 2001 10:21 AM
Since it is important for you to let us know what you do for a living, could you tell us what type of engineering you practice? Aerospace? Mechanical? Electrical?
I AM an engineer also.Steeve
Aug 24, 2001 10:39 AM
I agree 100% with alex's response.

FWIW: I am an aerospace/mechanical engineer.
where ?PeterRider
Aug 24, 2001 10:47 AM
(just out of curiosity, since I work also on space stuff, for nasa)
where ?Steeve
Aug 24, 2001 10:55 AM
I live in NE Florida. I work as a design engineer for a major Defense contractor.

How about yourself? Do you work at Canaveral?
where ?PeterRider
Aug 24, 2001 12:22 PM
nope, at JPL in California, doing image processing engineering.
ME too!nova
Aug 24, 2001 10:58 AM
I'm an engeineer. Unlike the rest of the engineers here, I'm not compelled to SHOUT IT from the rooftops!
the rooftop shouting is for the lawyers!bob the rabbit
Aug 24, 2001 1:19 PM
ME too!Jofa
Aug 24, 2001 4:27 PM
Alex has been here for some time, and to my memory has been fair, humble and accurate: both his 'engineer' handle and the current post title are I imagine meant flippantly.... the second in 'touché' response to the previous post.

I respond on this point only because by and large I share your irritation with this kind of self-publicising... here however I think the charge is unwarranted. He was, in any case, dead right- (in my opinion of course).

Jofa

not an engineer either
True but arguably neglagibaleChris Zeller
Aug 24, 2001 8:36 AM
Their claim is true, you really need a picture to show this graphically, but from the 9:00 position to the 3:00 position (as viewed from the left side of the bike) your leverage is a little smaller. On the flipside. from the 3:00 position to the 9:00 position the pedal stroke is longer. The former is a very inefficient part of the stroke anyway. Maybe you could gain something by this in the form of weight savings by using a slightly smaller crankarm than you might otherwise. I think the real advantage of these pedals comes in their light design, and possibly cornering ability.

The impact of pedal leverage on efficiency is very complex. With combinations of crankarm length, gear ratio, etc, I don't think that anyone really knows what is most efficient. More leverage from a longer effective crankarm length, generally means a slower cadance (on account of the larger circle) all things being equal. I think it really depends upon the individual and your relative cardiovascular strength vs. muscular strength. For what it's worth, in Armstrong's training mannual he states that he prefers shorter crankarms than most other competitive cyclists, while spinning smaller gears at a higher cadance. Here, there would be no advantage in increased leverage.
longer deadspotsDog
Aug 24, 2001 8:40 AM
I think the higher stack height mainly results in longer deadspots at 12 and 6. At 12, your foot spends time going over the pedal, rather than moving directly from up to down. That's a theory I read somewhere.

Nonetheless, the differences among pedal systems are so small, I doubt it makes much significant difference. Besides, other issues, such feel and comfort, likely matter much, much more.

Dog
Dog, your comment a few days ago aboutraler
Aug 24, 2001 9:17 AM
Speedplays bruising your feet interested me. I too, appreciate the lightness of the Speedplays, but the extremely slippery float seems to require mental and physical involvement to keep the foot straight during pedaling. I have become accustomed to it but I wonder if it is less efficient. Any tests on this? The Zero will hopefully cure this.

Regarding the bruising you experienced, I didnt find the Speedplay to be uncomfortable in this way. Although I havent been on any huge rides (I just got these as my newly healed ankle makes it tough to release from the average pedals) but doesnt the SP cleat disperses the weight as wide or wider than a LOOK pedal? The actual pedal body doesnt actually touch the sole, or does it on certain configurations??

I guess my other question is, how did this pedal put that type of bruise on your foot through a cleat and through a carbon or similar shoe sole?
Wouldn't pedal/cleat area matter - for foot bruising comment?PdxMark
Aug 24, 2001 12:57 PM
Dog, your comment a few days ago about Speedplays bruising your feet interested me too - it made me wonder 2 things:

1. what is the total area of shoe sole contact between cleat/pedal combination for the various pedal types.... because even though speedplay pedals are small, the cleat/adapter has a pretty large area over which the load would be distributed, I think - how do the others compare? Couldn't bruising been a matter of the cleat bolt(s) pressing slightly against the insole?

2. although total area matters, so would the degree to which the area is "together" - for example, standing on a flat ring could give alot of total area, but the hole in the middle would mean there could be hot spots at the ring edges... so thinking "aloud," I would think that you want alot of total area as well as a ratio between total area and bounded area to minimize "holes"

As for me, I'm a Fred who rides Frogs because I ride alone alot and dread the thought of a long walk in road shoes/cleats...
How about the claim that Ritchey and SPD cleats....MrCelloBoy
Aug 24, 2001 8:47 AM
are intertchangeable?
My experience is that the Ritchey pedals (set to the lightest tension) put a death-grip on the SPD cleats! In reverse the SPD's will sometimes not retain the Ritchey's. I think a certain amount of readjusting of tension can help (to a degree) but you sure cant just jump on someone elses bike and stomp away with any consistency.
How about the claim that Ritchey and SPD cleats....Pogliaghi
Aug 24, 2001 9:58 AM
Yup, not interchangeable in both directions, 'though my experience is the opposite. Death grip on my Ritchey cleats when I step into SPD pedals. Others with SPD cleats have clipped onto my pedals w/o problem.
Ritchey and SPD cleats....(ACE)
Aug 24, 2001 9:39 PM
Mine work perfectly either way.
Over Blowngrzy mnky
Aug 24, 2001 8:49 AM
Efficiency is defined as power out over power in. If not all the power is making it out it begs the question as to where it went. The only possible explanation would be along the lines that a greater foot to spindle height results in more rotation of the pedal with respect to the axle and thus more power lost in the pedal bearings due to friction. The biomechanical aspect says that the increased foot axle distance results in an increased moment on the foot which must be compensated for by additional effort on the foot leg to keep proper ankling. It's highly suspect that something like 3/16" is going to make that much difference. If it were truly signifificant the elite racers wouldn't be using things like Look pedals. This claim is right up there with the claim of aftermarket rear der. cage pulleys.
Yaraler
Aug 24, 2001 9:28 AM
Ya, I can see if you had 2" pedal blocks (like kids sometimes use on tricycles if theyre too short) that it would cause problems as you pulled through the bottom or pushed over the top because your force would just want to turn the pedal on its axle rather than turn the crank. But, the minor differences between all the current pedals arent going to make much difference.
Yup, marketing hype (nm)Pogliaghi
Aug 24, 2001 9:53 AM
Over Blownpedal man
Aug 24, 2001 10:50 AM
Grzy mnky: Didn't you read what alex the engineer posted? He was correct.
Yeah - So?grzy mnky
Aug 24, 2001 2:13 PM
I didn't disagree, but offered my own analysis. You're not confussed are you?
Alex's and GM's descriptions...Jofa
Aug 24, 2001 4:32 PM
...are consistent with each other: both express doubt at this dubious 'efficiency' stuff. What was your point?
Q factor?wes
Aug 24, 2001 3:04 PM
Nobody has mentioned this, but it sounds suspiciously like Q factor to me. Now, I have to admit that I don't understand Q factor, so maybe someone can explain it. But the idea that "the smaller the distance from the pedal axle to the shoe sole, the greater the rider's efficiency and power output" is similar enough?
Noraler
Aug 24, 2001 3:29 PM
Q-factor is the distance between the two pedals. Grant Peterson (of Bridgestone, now owns Rivendell) was a big proponent of low q-factors. I guess it seems right to a point. I think ideally it should be based off your hip width. Maybe girls should have a wider q- factor??? Who knows.