# Pedal stack height - why is this important?



## soulfly_nyc (Feb 16, 2007)

Hi,

I've recently looked into the stack heights of 3 pedals:

Look Keo - 15.7mm
Shimano 7900 - 13.7mm
Speedplay Zero - 11.5mm* or 8.5mm**

*3hole cleat
**4hole cleat

Why is pedal stack height important? 

Is lower stack always better for everyone or are there bio-mechanical factors particular to the individual racer?

Thanks for your thoughts.


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## Kerry Irons (Feb 25, 2002)

*Stacking it*



soulfly_nyc said:


> I've recently looked into the stack heights of 3 pedals:
> 
> Look Keo - 15.7mm
> Shimano 7900 - 13.7mm
> ...


Lower stack height means that your power is applied directly to the pedal with less effort required to control pedal position. Picture trying to pedal with 80 mm wood blocks on top of the pedals.

That's the theory. In practice, it's pretty hard to tell any difference and certainly riders are successful (racing) and comfortable (recreation and training) with all three of those pedals. If it makes a difference, it's not huge.


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## Hank Stamper (Sep 9, 2009)

It's not important to anyone but marketing departments who need something to talk about that can be objectively measured.

Even for biomechanical issues because those would be addressed by crank arm length shoes/inserts/wedges, float and of course saddle height.

yes at a certain point it would matter but not when you're talking about the differences that are about the same as the thickness difference in one pair of socks compared to the other which is the case.


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## pretender (Sep 18, 2007)

If you are a really serious cyclist you just get an axle surgically inserted in your forefoot.


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## Creakyknees (Sep 21, 2003)

pretender said:


> If you are a really serious cyclist you just get an axle surgically inserted in your mid-foot.


fify.


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## bikeman68 (Feb 10, 2009)

*Stack height on pedals*



soulfly_nyc said:


> Hi,
> 
> I've recently looked into the stack heights of 3 pedals:
> 
> ...


 Good 10 yr old query, this still applies for serious cyclists looking for an edge. For really trained, strong rider this is a bonus in a set of pedals you ride for any kind of racing , where power output is measured in watts. The many brands now can boast this to indicate how much or how little stack you have which affects what is called in USA as Rocking torque. It can give you a tech edge, but this is indeed an edge , not like doping.
YOu can see the history of wins on the older Look pedals going back to 80;s with the higher stack of 21-22mm (the pre Look Keo design) and at that time in 80;s 
In 1988 TIME came in on the scene and blew that position away with a bioposition of only 8.5mm below their own dedicated shoes made for their pedals . I tried them and felt the difference in torque as a strong rider who raced, and it did help, but was not the only factor to look at since the free float bothered my knees, so I went back to the old Shimano Look 7401s with black 0 degree Look cleats, the same pedals Lance won so much on. So I hope that helps with perspective, and to know its still the best rider who wins, and takes good care of themselves with best recovery. WE now have so many pedal makers that strive in tech features like this stack height, so the gap from my current Look Keo max from 2013 is what 16 mm? And speedplay with 11mm on average, that might help shave seconds in a Time trial or track pursuit, but not as important as your foot and knee comfort, so seek that most of all, and stack height after that if possible.


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## Peter P. (Dec 30, 2006)

How many people remember the old Dura Ace Dyna-Drive pedal, which had a very large, offset pedal axle (requiring special crankarms), that put the rotational axis of the pedal in-line with the ball of the foot?

Scroll down to see them.


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