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Buy Cranks to fit Yourself or the Bike? 165mm Cranks?(7 posts)

Buy Cranks to fit Yourself or the Bike? 165mm Cranks?jose_Tex_mex
Jun 29, 2002 10:40 AM
All,
How do you buy cranks or know which ones "fit" you. As stated in a previous thread (thanks for the ideas) my toes rub on the wheels when turning more than 15%.

I have 172.5mm cranks and have contemplated using 165mm. What's the story with 165's - are they legit road cranks or have they a special purpose. Would they be more for people who like to spin?

Finally, are cranks made to fit bikes first and then the person? I am unable to verify what was the OEM size crank for a GT ZR1.0 frameset - 52cm.

Thanks again for any constructive feedback.
You might like 'em ...Humma Hah
Jun 29, 2002 10:56 AM
I've run 170's most of my life, but have experimented with a set of 160's for off-road use on my cruiser. The idea was to gain a smidge of ground clearance. The cranks were run with a small off-road chainwheel. The switch to the shorter cranks felt quite natural.

I trained on the road with that set of cranks and low gearing for several months, working on developing some spin. I was surprised at how well the combination worked, and cranked out some pretty good times with them.

Switching back to the 170's, I felt awkward and inefficient at first, very aware of the extra bend in my knees.

Riding with a set of 175's, I nearly crippled myself on one century with IT band friction syndrome.

I'm told 165 mm is the standard length for track cranks. I've also seen a couple of studies indicating that good spinners tend to do well with shorter cranks. I consider myself a slow-cranking masher.

How short is too short? One study I read showed improved performance in some people the shorter the cranks got, but they stopped at something like 155 mm due to availability of hardware. Yesterday I was riding a paddle-boat which had cranks that must have been in the 100 mm range, and those were totally obnoxious.
re: Buy Cranks to fit Yourself or the Bike? 165mm Cranks?Fredrico
Jun 29, 2002 1:02 PM
Hummah Hah makes a good point about trackies using 165mm, but the reason is probably more to clear the banked track rather than getting up a good cadence.

I have a bike that with 170mm cranks has toe-front wheel overlap. It hasn't been a problem in the 15 years I've ridden this bike, my commuter, on which I have even mounted fenders! Yes, I've had to replace them once. My legs like 170mm cranks. I ride a 54cm. frame.

165mm cranks on a 52cm frame seems about right. They'd probably fit the legs better, too.
Wrong reason to change crank lengthKerry Irons
Jun 29, 2002 6:16 PM
Toe overlap is quite common and not an issue in the real world of riding. Crank length is something you adapt to - there has been no credible research showing that any particular crank lenght is preferable based on your body size. Shorter cranks make it easier to spin, that's about it.
Doesn't crank length essentially effect frame setup?Pecos
Jun 30, 2002 1:31 PM
The bottom of one's pedal stroke will be different depending upon crank length. KNOP will also be effected as will saddle height and fore aft position. One cannot simply change crank length without effecting the other parameters. This then can then have a profound effect on how a particular frame fits. JMO
to fit bothelviento
Jun 29, 2002 6:33 PM
1. the bike should fit you, and the crank should fit both you and the bike.

2. Toe overlap is almost inevitable for sub 53cm frames and it's not a problem unless you want it to be. As long as you are in any decent speed (6mph+?), you won't need to turn that sharply. Even if you do, you can simply turn without pedaling.

170 cranks should work on a 52 frame.
All: Thanks for the feedbackjose_Tex_mex
Jun 30, 2002 6:33 PM
Thanks for all of the help and great feedback. I think I will keep my 172.5 cranks. I'll plan my next drivetrain on your ideas - which probably won't be long from now.