Short Cranks
Summary
After reading much of supposed benefits, especially for the knees, I
wanted to try shorter cranks. After much searching the web I finally
ordered the shortest set of Thorns cranks (140mm) from St John Street Cycles
(highly recommended shop, and they delivery worldwide) and installed
them with 40/28T first on my Pashley
PDQ. I adjusted the boom length so that my legs where still only
just bent at the longest point of the pedal stroke.
After a short period of acclimatising I am hooked. Spinning is much
easier (100rpm is easy compared with 90rpm before) and my knees feel
much better, but of course YMMV, and it is also still early days for
me. Speed at the moment seems the same as before, however since my
spring cycling I have had a 4.5 week holiday without cycling and also
fitted new tyres to the PDQ so the comparison may not be fair.
And I have bought another identical crankset for my
Hase Kettwiesel.
Pros and Cons
Benefits: higher cadence and less knee bend, more clearance for
fairing, less risk of front wheel strike (SWB) or derailleur strike
(FWD lowracer). With less knee bend OSS handlebars can be set lower.
Negatives: cost: to buy new crankset or re-drilling existing
cranks and then propagate to all bikes you own.
Tips
- Before ordering first check how much boom and/or seat adjustment is
available on your bike: you will probably want to extend the distance,
e.g. 170 - 140 = 3cm further. If you are near the limit you may have
problems !
- You may want to choose a crankset that allows a good variety of
chainring sizes to experiment with what gearing works for you (some
people seem to stay with the same chainring sizes, other make
adjustments because of faster cadences). So far Gain Ratios have
worked for me.