If all things are equal how much do you need to raise the front end to be able to go to a centimeter longer crank. And maintain the same hip angle. Say 155 to 165. I'm currently on a 155 not performance reasons but because of hip impingement at the top of the pedal stroke. But if I wanted to go to a 165 crank how much would I need to raise the front end to maintain that angle.
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Re: Going to a longer crank??? [Fishbum]
[ In reply to ]
With hip angle defined with cranks near the top of stroke- a little in front of TDC somewhere anyway, I would think that relative to BDC, you are going to have your top pedal 2cm higher- so I'd bet about 2cm +/-. I made that up, but maybe it makes some sense.
Re: Going to a longer crank??? [Fishbum]
[ In reply to ]
Fishbum wrote:
If all things are equal how much do you need to raise the front end to be able to go to a centimeter longer crank. And maintain the same hip angle. Say 155 to 165. I'm currently on a 155 not performance reasons but because of hip impingement at the top of the pedal stroke. But if I wanted to go to a 165 crank how much would I need to raise the front end to maintain that angle.
Re: Going to a longer crank??? [MattyK]
[ In reply to ]
MattyK wrote:
Fishbum wrote:
If all things are equal how much do you need to raise the front end to be able to go to a centimeter longer crank. And maintain the same hip angle. Say 155 to 165. I'm currently on a 155 not performance reasons but because of hip impingement at the top of the pedal stroke. But if I wanted to go to a 165 crank how much would I need to raise the front end to maintain that angle.I'm not sure I'm explaining it well.
Yes I would have to drop the front to match the seat drop if I wanted to stay the same. BUT.... I'm trying to maintain the hip angle at the top of the pedal stroke with a longer crank. Forget that I would need to lower the front. I'm just curious what the ratio is for amount of stack to hip angle. I'm sure it's not 1 to 1. Make sense.
I have come up in the front recently. And I'm wondering if it's enough to get a longer crank.
Re: Going to a longer crank??? [Fishbum]
[ In reply to ]
Why do you think you want a longer crank?
(leave your SO out of this) /pink
(leave your SO out of this) /pink
Re: Going to a longer crank??? [Fishbum]
[ In reply to ]
Ah yes, you’ll be lowering saddle by 1cm, so up 1 cm is my guess on pad Y.
Re: Going to a longer crank??? [Tom_hampton]
[ In reply to ]
More crank options at that length. Shimano.
Re: Going to a longer crank??? [Emma'sDad]
[ In reply to ]
Emma'sDad wrote:
Ah yes, you’ll be lowering saddle by 1cm, so up 1 cm is my guess on pad Y.He's lowering the saddle by 1cm, but the knee will now come up by another cm relative to the hip.
So raise pad Y by 2cm.
Re: Going to a longer crank??? [Tom_hampton]
[ In reply to ]
Yes, agree, but isn’t pad Y measured from BB and not pedal? Lowering saddle 1cm in effect brings front up 1 cm. One to go, no?
Yes, pad Y is measured from the crank center. But, hip angle is driven by pedal height to saddle height... And shoulder height.
So, when you lengthen the crank by 1cm it gets 1cm closer to the saddle. So if you don't move the saddle, you need to raise the shoulders by 1cm (raise the pads 1cm).
But, to equalize the pedal extension you need to drop the saddle by 1cm, which closes down the hip angle again. So, you again need to raise the shoulder (pads) by another 1cm.
So, when you lengthen the crank by 1cm it gets 1cm closer to the saddle. So if you don't move the saddle, you need to raise the shoulders by 1cm (raise the pads 1cm).
But, to equalize the pedal extension you need to drop the saddle by 1cm, which closes down the hip angle again. So, you again need to raise the shoulder (pads) by another 1cm.