Coker crank length learnings

I’ve been a bit schizo on my crank lengths lately on the GB4 36”. After 500+ miles with 150s, I swapped up to 170s for a while, then back to 150s, and now down to 140s for the last 100+ miles. When I was discussing my pending shift to 170s some months ago, John_Childs mentioned he was riding 170s temporarily “to improve my spinning technique”, with the theory being if you can learn to spin fast and smooth with the longer cranks, it will improve your spinning with the shorter ones. I keep detailed riding logs including both my average speed for each ride, and my top speed for each ride. After averaging both the average speed and the top speed figures, I have to say JC’s thinking is proved out by my experience. Check out the data, which is in chronological order:

Crank…Miles…Av. Speed…Av. Top Speed

150s…547…8.86 mph…11.75 mph

170s…136…8.64 mph…11.84 mph

150s…243…9.47 mph…12.85 mph

140s…105…10.21 mph…13.45 mph

What confirms the theory I think is the Average Speed. It dropped, predictably, when I went from 150s up to 170s, but after I swapped back to 150s, it was notably higher than the period with the same 150s prior to the change to 170s. I can’t explain the anomalous Top Speed data point with 170s, but the 150 before and after data in this category still supports the theory.

I think the 170s also helped prep me for success with the 140s. In the 100 miles since I’ve installed them, I’ve achieved both my fastest recorded speed (15.3 mph) and my fastest average speeds over longer rides (11.3 over 10 miles and 11.5 over 20). The one trade-off I was expecting with the 140s was decreased climbing ability, although interestingly I’ve been able to get up all of the steepest hills I could climb with the 150s and 170s. Much less of an issue than I expected, and the extra speed more than compensates. I think I’ll be applying Loctite to my pedal threads this weekend.

Re: Coker crank length learnings

On Wed, 29 Jun 2005 01:39:33 -0500, “tomblackwood” wrote:

>I have to say JC’s
>thinking is proved out by my experience.

Although JC might well be right, I’m not convinced by your data. It
could just as well be that it’s just more riding experience (on
various crank lengths or not) that yields you better spinning ability.
I have ridden various wheelsizes and crank lengths in no particular
(thought-out) sequence, and have also kept logs of cadence and speed.
Like you, I noticed improved spinning and speed but I attributed it to
more general uni hours under my butt.

Klaas Bil - Newsgroup Addict

“As with all great social movements, the origins of mountain unicycling are unclear. - Hannah Nordhaus (Los Angeles Times)”

Re: Coker crank length learnings

try 125’s & maybe 110’s before you get the loctite out!

Re: Re: Coker crank length learnings

I think that’s a legitimate theory as well. The reason I didn’t go that way is that in looking at the 547 miles with my first use of 150s, the average stayed pretty constant, i.e. there was no discernable learning curve in there. Then, after only 136 additional miles…this time with the 170s…there was a discernable learning curve.

I’m with Klaas on this one. I’ve watched you ride over the last couple of years and your posture on the Coker has improved dramatically. The amount of energy you are putting into fore-aft balance is substantially less than before. I attribute that primarily to riding experience. You also have been much more highly motivated to do distance rides. The crank length variation may provide some learning but I think not quite so much as time in the saddle.