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BB too low? pedal bite
Just finished building up my fixed conversion. It's a 80's Motobecane Super Mirage frame.
Anyway, the BB is way low and I get pedal bite with 170 cranks. Low enough that I scrape going over a speed bump in a straight line. Aside from going to 165 cranks (which I will be doing), are there any other little things that I can do to increase the BB height? |
clipless, i don't like them, but they'll reduce the risk of pedal strike, especially with 165s
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Originally Posted by cid499
JAside from going to 165 cranks (which I will be doing), are there any other little things that I can do to increase the BB height?
no |
Any disadvantages of going to super tiny cranks? Like 150 or 155 range. I"ve seen some on ebay
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Have you had any other pedal strike issues? I ride with 170s on a road conversion and one of my only two pedal strikes came when going over a speed bump. I think it may be a far more likely place to strike than in a corner. Basically though i have to keep pedal strike on my mind when cornering hard it is an insignificant issue for me.
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I just went for a ride right now.. going around a bike circle at a very moderate speed, i struck pedal. Then, going EXTREMELY slow on a very slightly off camber and very slightly downhill turn, the pedal struck again. From the ground to the bottom of the BB is only 9 inches, and about 9.75 to the center of the BB spindle.
Anybody else have numbers to compare to? |
It sounds like you have an unusually low-riding bike. My eighties' roadie has 1/2" more ground clearance than you have (with current 20mm tires), and I thought that was already a bit low for a satisfying fixie. Worry about pedal strike is a frustrating distraction while riding, even if the worry is unfounded.
Fatter tires will probably help a bit. |
if you're rocking super wide platforms that is also a problem, for turning, not speed bumps
try narrower pedals |
I had an old Bianchi conversion with 170 cranks. It was an english style frame, so its bottom bracket was low. Buy cheap pedals.
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There's a few options, if the problem is bad enough it may warrant all of the below:
1) Buy 165 cranks. No brainer. 2) Buy some MKS GR-9 pedals as they give just about the best cornering clearance, or if you want, buy clipless. 3) Fatter tires, like some 27x700's. That's about it... |
The pedals I have right now around only about 3 mm wider than the GR-9's, so I don't think I'll be getting those. I have looked into getting a set of 165 cranks and bigger tires.
But have you ever heard of a roadie that was just not suitable for a conversion? |
Are you running 700c wheels or 27" wheels. The frame was probably intended to be used iwth 27" wheels with 1 1/4" tires or larger. If you've got 700cs with 23mm tires on there, that'll lower you BB considerably.
Whichever is the case, you can gain BB height by mounting larger tires. |
I am indeed running 700c wheels with 23mm tires. I didn't know that a wider tire is also taller.
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Originally Posted by cid499
I just went for a ride right now.. going around a bike circle at a very moderate speed, i struck pedal. Then, going EXTREMELY slow on a very slightly off camber and very slightly downhill turn, the pedal struck again. From the ground to the bottom of the BB is only 9 inches, and about 9.75 to the center of the BB spindle.
Anybody else have numbers to compare to? |
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