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ultegra cranks(6 posts)

ultegra crankssoulsurfer104
Sep 1, 2003 5:57 PM
i am planning on buying an Ultegra crankset and i was looking at it on supergo.com and i noticed that i have three different sizes to choose from: 170mm, 172.5mm, and 175mm. what do these different sizes mean and which one should i choose?
re: ultegra cranksAl1943
Sep 1, 2003 6:04 PM
Those are the optional crank lengths. Generally smaller people will have smaller cranks. My 5'1" wife rides 170 cranks. At 5'9" I ride 172.5 cranks.
re: ultegra cranksSherpa
Sep 2, 2003 12:44 AM
For general road racing and touring, those with road frames smaller than 21" (54 cm), or people less than 5'9", will want a 170 mm crank. Frames from 21.5" to 24" (55 to 61 cm), people from 5'9" to 6'1", will probably want cranks from 170 to 172.5 mm. Those with frames over 24.5", typically over 6'2", tend to want cranks of 172.5 to 175 mm.

You can calculate your correct length using this tool ...
http://www.machinehead-software.co.uk/cyclist_crank_length_calculator.html

Good luck
Crank length choiceKerry Irons
Sep 2, 2003 5:12 PM
It is generally the case that longer cranks make it harder to spin, and high cadence is the best way to minimize knee problems.

Every increment of crank length is about 2-3 rpm. Going from 170 to 175 is about 5 rpm. Spinning is more physiologically efficient, all else equal.

You will find no high quality data to support any particular crank length as being better than any other. This is true whether or not you correct for leg length, femur length, etc. What little research has been done on crank length suggests that people adapt to different crank lengths and there is no optimum or formula related to body proportion. On the other hand, you will find lots of anecdotal or low quality data to support all kinds of conclusions, and more theories than you can shake a stick at. A rider's response to changes in crank length is 1) highly individual, 2) dependent on riding style and the event (TT, climbing, crits, track racing, etc.), and 3) most important, highly adaptive. This is why it is so hard to study the effect of crank length.
re: ultegra cranksMazinger
Sep 3, 2003 10:18 AM
I just put a set of 172.5 Ultegras on my bike. The factory crank was the same length. I've been pretty happy with it.
My bike is a 52cm or 53cm by the way.

Yeah, I know...I was no help :)
re: ultegra crankssoulsurfer104
Sep 3, 2003 5:30 PM
ok....going to try and help those of you who are trying to give me advice. i am 5'11", 138lbs and have long legs. i have a Giant Compact Road frame, size Medium. i spend most of my time riding on flat ground at 17-24mph. maybe that will help. thanks everybody who responded so far.