What length crankset for my wife?

[Grgic]

The wife recently got back into cycling so we purchased for her a LOOK 566 that came with a 53/39 Ultegra 10sp chainset (specifically a fc 6700 172.5mm) as part of the Ultegra groupset on the bike.

I want her to move to a compact crankset so it's easier for her to get up hills. I'm thinking a Shimano Ultegra 6750 hollowtech ii compact chainset is the way to go (Dura Ace is too far outside the budget).

The question is, she's quite short (about 5foot nothing) and I'm wondering whether she should instead be using a 165mm or 170mm chainset. Thoughts?

[Duck!]

165mm would be most appropriate for her stature.

[Nobody]

What Duck! said will probably do if she doesn't have knee problems. If however she does, you can use specific crank length advice and get shorter cranks from Japan.
http://www.myra-simon.com/bike/cranks.html" onclick="window.open(this.href);return false;
http://www.alexscycle.com/cranks/road-1 ... crank.html" onclick="window.open(this.href);return false;

At 173 or 5'8", I'm using 165s, but I have knee problems. I found shorter cranks to help to a minor degree (some see greater benefit) but the main change I noticed was my pedal action was smoother under load. So I appear to have more control over the cranking action.

[Grgic]

Thank you for the feedback. That eases my mind greatly on the next purchase. Thanks!!

[Grgic]

So it looks like the 6750 is being phased out with not a lot of places stocking/restocking them. Would the Ultegra 6800 crankset (listed as 11sp) work with the rest of a 10 spd groupset?

[DarrylH]

Was talking to a friend this morning - she is 5ft 1in and was measured up for a new bike using 650 wheels. Crank length for her was estimated to be 155mm but of course this depends on leg length rather than height. She was building up an Orbea Diva from scratch.

[Duck!]

So it looks like the 6750 is being phased out with not a lot of places stocking/restocking them. Would the Ultegra 6800 crankset (listed as 11sp) work with the rest of a 10 spd groupset?

Yes. The bonus of 6800 is that all chainring combinations use the same BCD, so you don't need to replace the whole crank to change between standard & compact configurations (but big rings are expensive due to the hollow construction).

Second bonus is that if you have the dark grey version of the 6700 group, the colour of 6800 is almost identical, so the crank will not stick out like dog's proverbials.

[ColinOldnCranky]

More specifically you should start with inside leg measurement rather than overall height.

http://www.cptips.com/crnklth.htm
http://www.nettally.com/palmk/Crankset.html

[CKinnard]

I recommend to riders getting back into it after 35-40yo, to go a shorter crank than standard.
The reason being the hip and knee flex less, which will reduce irritation of knee menisci and hip labrum, both of which are prone to debilitating degenerative change from sporting injuries when young and general ageing. Even if you don't feel pain, cycling can be accelerating their wear, especially if flexing these joints further.
Using a shorter crank also allows you to get lower on the bars because you knees are not coming up as high.
Another advantage to reduced hip flexion is that you are less likely to irritate/compress the main arteries to the legs and end up with compromised blood flow - exercise induced iliac endofibrosis.

[Grgic]

Thanks again folks, I know which one i need to get her now. 165mm 6800.