Yet Another Cycling Forum
General Category => Freewheeling => The Dark Side => Topic started by: Valiant on 10 May, 2008, 05:44:07 am
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Remind me again. When the crank is fully straight, should my leg be fully straight? Cos at the moment it pretty much is and I'm thinking that in combination with my large cranks cos be causing the discomfort in my knees?
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I assumed that there needed to be a slight bend in the knee to avoid locking the knees.
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Remind me again. When the crank is fully straight, should my leg be fully straight? Cos at the moment it pretty much is and I'm thinking that in combination with my large cranks cos be causing the discomfort in my knees?
Regardless of the fact that you're using different muscles in the recumbent position, it's pretty the same as DF position when it comes to leg length on a fully extended crank. It sounds like you want to adjust the boom slightly so your knee is bent a little more on this fully extended position.
But you may also be getting problems with these large cranks as you describe them on the up stoke too. If they're too long then this might be causing a little strain on the knee when you begin the down stroke [when the knee is closest to your chest].
Leading on from that, what seems to be favoured a lot by recumbent riders are shorter cranks, the exact size depending on the length if your leg. It's not uncommon for riders to have 150mm. Changing the crank length will also affect the gearing. In effect you'll be adding at the high end and losing on the low gears due to a change in leverage.
A lot of recumbent riders swear by them, particularly in relation to knee problems. Personally I'm happy with 170mm, but being 6ft 3in that is probably about right for somebody my size anyway.
It's another one of those personal, try it and see, experiments. See if you can try some somewhere before you buy. They can be tricky to source.
There's loads of stuff out on short cranks out there on the web. Brol (http://www.bentrideronline.com/messageboard/index.php?) is a good place to start.
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as a rough guide i sit in the seat and put my heel on the pedal . the leg sould be strait. when you then put the ball of your foot on the peal the leg should have a slight bend in it :)
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Aye I do need short cranks being 5'3. I shall adjust the boom accordingly :)
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You can get 155 cranks from www.toxy.de. They don't accept CC though so PM me should you require them as I can get my missus to pay via bank transfer.
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Wouldn't that mean that I would also need a new BB.
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Wouldn't that mean that I would also need a new BB.
It looks like a standard square taper fitting in the pics, which is cheap enough... What does the Challenge have fitted?
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FSA Mega Exo whatever that is lol
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You'd need a new BB then... About £15 for a basic one.
IIRC, the Megaexo design uses ISIS splines.