This is a continuation of: http://www.bikeforums.net/showthread...tighten-pedals
A few people seemed interested in my short cranks (100mm) setup, and I have some more background and pictures.
I have a knee flexion problem, so I used this pair of crank arms shorteners for 3 years:
then this pair for like 2 years:
They both sorta worked but not all that well. I would get tons of noise and creaking and I could never tighten them down enough. They would dig holes into the cranks too from all the repeated stress. Once the second one got a little loose and I broke a screw in half and it fell off with the pedal. Actually I think that happened a couple times.
Here's a picture of the second one my *old* bike, and you can see the hole that the first setup dug:
So then I discovered these shortened cranks for a new bike:
They are done by Mark at bikesmithdesign: http://www.bikesmithdesign.com/Short...s/IsoFlow.html
From the other thread, I think I just forgot to tighten them. I had a million different concerns at the time -- I had an ordeal with making the handlebars high enough to account for being 3" higher off the ground. The cranks were the 3rd thing or 4th thing on my mind and that was my first time putting a bike together.
Although, I didn't feel them being loose when riding for that 10 miles.
The work looks solid to me and you can see on the page that he's pretty conscientious about making sure the cranks have enough metal to drill around and stuff like that. Seems like he's done it many times before.
I was just surprised that the loose pedal made it fail in such a spectacular manner, but apparently people have seen the same thing happen before on regular cranks. I didn't expect the threads to come out in pieces like they did.
BUT, here's a high school physics question: Suppose that I'm using 95mm cranks (this set was 95 not 100), and a guy who weighs the same as me is using 175mm cranks.
Now we both accelerate from 0 to 20mph in 30 seconds (or whatever). How much more force am I putting on the pedals than he is?
I feel like it must be a lot more, although I don't consider myself particularly strong. I can keep up with most riders even with the 95-100mm cranks. It works fine. I can even accelerate faster sometimes just because it's easier to make these small turns from standing still.
I think that 95mm are the shortest cranks offered. So maybe the shorter the cranks are, the more force they have to be able to withstand for the same amount of power. That could certainly account for many the problems I've had with the crank arm shorteners as well.