Short Cranks

[Moonglow]

First of all, hi everybody!

I think I need to change my crank length.

And then a bit of background:

I am short. Very short. Under 5 feet tall.

I got my Specialized Crossroads when I moved to Edinburgh 4 years ago. Loved it, perfect for the riding I was doing (typically 5 miles max at a time), and better than any other bike I'd owned; not hard when I'd only had Apollo cheapies.

Aaaanyway, since then I've broken my foot very badly coming off my bike, been mostly out of the saddle for nearly 3 years losing most of my strength and fitness and moved to the country.

I've been riding more often recently and found that my lungs and heart are still surprisingly happy, but my legs are not. Now I'm in the country my rides are longer, more ups and downs, weaker legs etc. I went on a ride last week to my grandparents, 27 miles each way. Again, my lungs were happy, but the last 15 miles were hell on the legs; both muscles but more on the joints. I couldn't spin and I couldn't stand.

I think when I was in Edinburgh my rides just weren't long or hard enough for me to notice the problem.

I want to start commuting 15ish miles (each way) at least once a week and ride up to Edinburgh and back next summer!

My Kit: 700c Wheels, 48/38/28 chainset, 11-34 megarange cassette.

It's really difficult to find short cranks, I've discovered, but I've found someone that can shorten your existing ones.

Questions:

1: Looking at various sites, a 150mm crank or a 135mm crank has been recommended. Looking at gain ratios, 150 would mean about half of the combos on my 48 ring would be too hard to use except downhill. 135 would mean almost all of my top ring would be too hard to use.

Would you recommend a) 150, getting quite a good length for spinning and putting up with some of the gears being rarely used OR 135, getting apparently a better length biomechanically and having to change the chainrings and chain?

2: What effect might this have on my riding position, saddle position, reach, acceleration etc etc?

3: If I weren't a poor student, wouldn't it just be better for me to build a bike from scratch (especially since I'd love to move onto a road bike anyway!)?

Thanks, Jonathan

 

[Dayvo]

Welcome to CC, Moonglow!

Interesting introduction!

I'm not too familiar with the theoretical side of cycling, but I would suggest that either you enquire about good quality junior cycles, or have a look at women's cycles - or at least the sizes of components on the bikes!

Just a moment ago, I read that Emma Pooley is only 5'2", so possibly you could use her set-up as a guideline.

Good luck and happy cycling.

By the way, I think your legs will get stronger the more you cycle. Hills take a while to get used to if you have been cycling on the flat.

 

[RedBike]

I'm not convinced that switching to a very short crank will help you. Short cranks possible; but not 135mm.

 

[Amanda P]

Hi Moonglow.

Mrs Uncle Phil is a similar height to you I think; she's 4'11" or so.

Finding a bike to suit someone of that size is really hard: children's bikes are mostly toys, and adult bikes are all too big - in all dimensions, not just crank length. Critically, 700 or even 26" wheels are really too big, as they force the frame to be quite long for a rider of that sort of size. 650s might be about right, but for road-riding purposes, they're pretty much obsolete.

But your question was about cranks. Well, up to now you've been riding on standard cranks (170mm or thereabouts) with no great difficulties, I imagine. Mrs Uncle Phil has been doing the same.

Recently we tried a tandem. The shop fitted 135mm cranks on the stoker end (from Hase) and Mrs Uncle Phil really liked them. She has a recumbent with 150mm cranks on, and she likes those too.

In practice, you may find that your need for gear ratios doesn't change as much as you think. As a compromise, why not go for the 150mm cranks, keep your existing gears, and see how you get on? You could change to slightly smaller chainrings as a next step if you feel you need to.

In terms of your riding position, well short cranks won't change the reach of the bike, but it might allow you to set the saddle lower. (You could also use a frame with a lower bottom bracket, as there's less chance of grounding the pedals on corners). You might be more comfortable putting your feet on the ground when stopped at junctions like this.

A new bike? Worth considering, but as a poor student, it may be difficult to find one that really suits at a price that fits. Given Mrs Uncle Phil's experiences, I would consider something with smaller wheels than standard - a Moulton fits her beautifully, or a Bike Friday or Airnimal - and choose short cranks for it if you wish.

You're very unlikely to find any budget bike that will fit you and be of decent quality.

The cheapest option may be to stick with what you have and work on improving your fitness. Short cranks may help a bit, but it won't be a magic bullet.

 

[Moonglow]

My legs used to be fine because my main sport of the previous 7 years was dinghy sailing which was pretty intense exercise. It's sad that cranks won't be a magic bullet, I'll just have to become a better cyclist Seriously though, I know I can't expect a quick fix for this, it's just the same as my photography, a 'better' camera wouldn't compensate for being a crap photographer.

My initial thought was your compromise Uncle Phil at £40 to shorten a pair I can afford to try a less radical option first.

Those small wheel bikes look awesome! I might have to start a pot to save up for one of them! All I have to do is spend less on photography and dance events...

Thanks for the input guys. Jonathan

 

[Moonglow]

Oh, and I should probably say, cycling isn't my major recreational activity and never will be. I just want to be able to commute better, blast about sometimes, do some occasional light touring and improve my fitness for other things. I don't really mind my muscles complaining, they'll improve, I do however want to take care of my joints.