Short Cranks

Recumbents and all feet forward machines

Short Cranks

Postby rdp_au » Tue Oct 09, 2012 10:19 am

There seems to be a view that shorter cranks work well for recumbents and I have been contemplating trying out some on my Bacchetta for a little while. With the standard 172.5 cranks it felt like I was overextending my knees just a little, but I have been reluctant to move the seat forward, as that would raise it even further and I am already pretty much at the limit of my leg stretch with a foot on the ground. However, in recent times I have been experiencing some discomfort in my right knee, the symptoms possibly attributable to overextension. So, when CRC had a special recently which allowed me to pick up a set of the same FSA Gossamer cranks in 165 size for just over $100, I had to give them a try. Fitted them last weekend and gave them their first run this morning on the trip to work.

First impressions – they feel quite different. The shorter crank length has effectively moved me closer and the sensation of overextending, most notable when starting off, was gone. I found my legs naturally spinning at a higher cadence and it felt much easier to maintain a smooth pedalling action, something I've never been very good at. So far so good. Next question was, how it would be climbing with nearly 5%less leverage? My morning run is mostly downhill, but there are a few reasonable hills to negotiate as well. Not surprisingly, I found I needed to change down sooner on gradual climbs, and I needed to be in a lower gear on a couple of the steeper bits. Checking Strava after the ride showed that my overall average was about the same as usual, and my speed going up the climbs was also pretty much unchanged. Will be interesting to see how they feel on the longer uphill climbs on the way home tonight.

So far, I’m happy with the change. I like the smoother pedalling action, and my knees seem to have responded well.
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by BNA » Thu Oct 11, 2012 11:42 am

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Re: Short Cranks

Postby william » Thu Oct 11, 2012 11:42 am

I have 155 cranks on my Corsa and after a few rides never noticed the difference.
I too developed sore knees initially but now I know it was due to both longer riding and mashing.
If your knees are troubling you firstly determine your leg extension and get that correct. Then listen to your legs, not your speedo and gear accordingly.
Then learn to peddle in circles, not push-pull. Feel your feet going completely around the crank circle.
Check also that your knees are aligned whilst peddling. Video yourself on a trainer. It won't matter much for short rides but will become detrimental with repetitious long rides of 2 hours or more.
Use your gears.

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Re: Short Cranks

Postby bradwoodbr » Thu Oct 11, 2012 8:30 pm

william wrote:I have 155 cranks on my Corsa and after a few rides never noticed the difference.
I too developed sore knees initially but now I know it was due to both longer riding and mashing.
If your knees are troubling you firstly determine your leg extension and get that correct. Then listen to your legs, not your speedo and gear accordingly.
Then learn to peddle in circles, not push-pull. Feel your feet going completely around the crank circle.
Check also that your knees are aligned whilst peddling. Video yourself on a trainer. It won't matter much for short rides but will become detrimental with repetitious long rides of 2 hours or more.
Use your gears.

william


wherejagit your 150mm cranks?
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Re: Short Cranks

Postby Baalzamon » Thu Oct 11, 2012 8:46 pm

I had 145mm cranks on my Bachetta Giro for the short time I had it. Got the cranks from Calhoun Cycles
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Re: Short Cranks

Postby chuckchunder » Thu Oct 11, 2012 10:02 pm

bradwoodbr wrote:wherejagit your 150mm cranks?


brad I've got a set of Carmina 150's in the garage I think.....
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