Bicycle Mechanics - Questions about Crankset

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View Full Version : Questions about Crankset


lerico
11-02-09, 11:53 AM
I am pretty short (5' 4") with short legs and am currently using a crankset with 175mm crankarm which i found a little too long for me. ie. knee bending a bit too much.

The Decore MTB crankset on my hybrid with 48-36-26T gives me the good gear ratio for me for now, I am looking to upgrade to a different crankset with shorter arms, ideally with similar gear ratio.

My first question is, most budget crankset only offer 170mm as the shortest crankarm. Is the 5mm going to make a noticeable difference to me?

My second option might be to go for a 165mm road crank. My second question for that is can I replace a MTB crankset with Road triple crankset? it's hard to find MTB crank in the taller 48T gearing


CCrew
11-02-09, 12:00 PM
You fail to mention what kind of bike this is on. 175mm is the norm for a MTB.

Road Triples generally have a different chainline dimension that may or may not work in your application. If you want shorter cranks, you may want to look at the Sugino offerings.

And 5mm should allow you to run higher cadence, beyond that there's not going to be a night and day difference.

barturtle
11-02-09, 01:26 PM
The Deore XT FC-M770 is available in a 165mm size. Assuming your current Deore uses the same 106/64 bolt pattern for the chainrings, you could just reuse your current ones on the new crank.


lerico
11-02-09, 02:07 PM
Oops, Thanks. My bad.

It's a hybrid bike with 700c wheel.

http://www.brodiebikes.com/2010/archive/bike.php?model=dynamo&year=09

ks1g
11-03-09, 10:24 AM
My 1st crankset was 175mm (cranks and group bought used off ebay). Didn't think it was that bad until I bought a new crankset @ 170mm. It made a HUGE difference and will never go longer. Also short-legged.

As long as the BB works with the cranks, you can likely try road or MTB cranks. I'd look 1st at what is the lowest gear ratio/gear inches you need for your riding and try to match that. A trick I've used is a road double (53/39) or compact double (50/34) with an MTB casssette (32 or 34t largest gear). You really need a MTB rear derailluer or maybe a long-cage (intended for road compact or triple) rear road derailluer to make this work.

HardyWeinberg
11-03-09, 10:53 AM
I like the sugino touring triple, 48 or 46/36/26 (I swapped out my 26 for a 24 for some big loads I have occasionally). It's square-taper, so you would need a square-taper BB which would only be ~$20 or so in addition to the price of the crankset. There are 2 models of the crankset, xd300 and xd600, one has 3 steel rings, the other has at least 2 aluminum rings, maybe all 3. Anyway, they both go down to 165mm cranks.

kaseri
11-03-09, 08:13 PM
Follow this link (http://www.nettally.com/palmk/Crankset.html)

RonH
11-04-09, 05:22 AM
bump