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- CommentAuthoro_O
- CommentTimeFeb 6th 2009 edited
what do you guys think of BMX cranks on fixed gears?
not for tricks or anything, just for riding around town.
i was thinking about running a 38/13 ratio -
- CommentAuthorpatrickviolence
- CommentTimeFeb 7th 2009
cool if you want a lower ratio.
man up and do 53/14. you won't. -
- CommentAuthorgreg
- CommentTimeFeb 7th 2009
you could get the same ratio with single speed MTB cranks, see e.g. race face cranks
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- CommentAuthoroctopus magic
- CommentTimeFeb 7th 2009
Bulletproof's work fine and you can get a 38 tooth rocket ring (I have both).
Running BMX ratios is dumb though. -
- CommentAuthorOtto Rax
- CommentTimeFeb 7th 2009
Go for it -
- CommentAuthoro_O
- CommentTimeFeb 7th 2009
56x11!
137.5 gear inches ftw! -
- CommentAuthoralexisfaster
- CommentTimeFeb 8th 2009
you might have a problem with the chain wheel coming loose if you run real bmx cranks, ie profiles etc. so you'll definitely need to use some loc-tite and torque that screw down but it should be fine as long as you keep an eye on it because they do come loose and its not pretty. -
- CommentAuthorterrible_one49
- CommentTimeFeb 8th 2009
Most BMX chainrings bolt onto the crank arm with just one big bolt, where as track/road cranks normally have 5 chainring bolts. Having it bolted on in more areas means it won't come loose as easy and also has less flex. To minimize flex, BMX chainrings are made super thick, however with riding a fixed gear (especially brakeless), a lot of pressure in put on that one single bolt that holds the chainring on.
I've seen the hole in BMX chainrings get warped into weird shapes from the pressure on it from riding fixed. So, if you are going to go the route of BMX cranks and chainring, make sure it's a super strong chainring that won't flex, and second that it has more than 1 hole in the chainring to bolt onto the crank arm.
WHATEVER you do...don't take that suggestion above to run Bulletproof cranks and Rocket chainring. Those are the two cheapest cranks and chainrings you can buy, and it will ride like shit and make tons of creaking noises and be out-of-round in a few days! I know from experience with those products.
Finally, look up the thread on here about bigger gear vs. smaller gear. I think you will see it's not only more efficient to run larger gears, but it's also less wear on your bike parts. -
- CommentAuthoroctopus magic
- CommentTimeFeb 8th 2009
I've been running Bulletproof + Rocket Rings for over three years.
The only time I had to replace anything was when I got hit. -
- CommentAuthorOtto Rax
- CommentTimeFeb 9th 2009
i think profile makes an adaptor to run true bmx cranks in a road/track BB shell -
- CommentAuthorthe rabbi
- CommentTimeFeb 9th 2009
it's just a euro bb. bmx bikes used to have them before they switched to a press fit bearing system
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