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Hello, I've got a mtb frame which has a BMX sized bottom bracket. I'm quite willing to run 3pc BMX cranks but could someone tell me about the sizes.
On my frame the bb shell is 69mm long and the ID of the shell is 51mm ... do I just need a std US BMX set up (and is that the same as a mid) or something else.
Thanks,
Stuart
Yes a standard US set up with bearings and cups will be fine. A mid bottom bracket shell is smaller, using just the bearings themselves and not the cups, as the bearings on a mid set-up press directly into the frame. Just bought one of [url= http://www.winstanleysbmx.com/product/14244/DK_MidUSA_Bottom_Bracket ]these[/url] (suitable for US or mid as it includes bearings and cups).
What frame is it?
You need a US/American bottom bracket, these use the same size bearings as a mid bb, but they are set in alloy cups which are then whacked into the frame.
They are not longer used in BMX really, but some mtb frames still have them
It's a Banshee frame, if it makes any odds.
Cheers
Oooh, a Scratch?? Post some pics when it's done. Always wanted one and I'm soo tempted by CRCs Brand X version.
Mamadirt thanks for the link, trouble is now I'm looking at Profile cranks :D. The Scratch on CRC is the proper job not a copy...just that they can't be sold under the Banshee flag in the UK due to Halfords owning the right to the name...they even come in a Banshee box.
Stuart
You could try one of these if you want to use a normal BB & cranks:
http://harriscyclery.net/itemdetails.cfm?ID=1335
s8tannorm - MemberMamadirt thanks for the link, trouble is now I'm looking at Profile cranks :D. The Scratch on CRC is the proper job not a copy...just that they can't be sold under the Banshee flag in the UK due to Halfords owning the right to the name...they even come in a Banshee box.
Stuart
Fantastic - that's my next project sorted 😀 I seem to be missing a 24" wheeler anyway.
As R979 says, an adaptor will let you fit normal mtb b/b and cranks (DMR do one which is on CRCs site). If you're set on Profiles, have a look at [url= http://cgi.ebay.co.uk/black-super-lightweight-d2000-3-piece-bmx-pro-crank-set_W0QQitemZ280310165955QQihZ018QQcategoryZ109118QQtcZphotoQQcmdZViewItemQQ_trksidZp1742.m153.l1262 ]these copies on ebay[/url] - I bought the 170mm crank arms and axle to go with the DK b/b and they're fine - maybe not as well finished as Profiles but hey, for the price, you can't go wrong (they have them in chrome too).
Those cranks look like a good deal, look very similar to profiles, the axle sounds exactly the same.
You should be able to pick up a 2nd hand set of profiles with a BMX bb for £50ish I'd imagine.
Mamadirt - The scratch is a 26inch wheeled frame isnt it?
Scratch will run either 24 or 26" wheels, SS or geared, comes with hangers for both. Thanks for the advice everyone.
Stuart