crank BB issue

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gates's picture
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Joined: Jul 2 2009
crank BB issue

I have a new set of 83mm altas cranks. My new frame has a 68/73mm bottom bracket. I dont think this is possible but I will ask. Is it possible to buy a new bb and use the same arms or dose the shaft that goes throught the bb shorter in 73mm bb.

Yeah you need the new axel.  Go to spin and get him to but a spacer from a bmx bb on the outside of the non drive side of the bike, over the axel.  Your non drive arm will be 10mm further away from the chain stays then the other arm, but the only cost will be a new bb maybe, and a spacer of sorts?  It would be very TOB of you.

gates's picture
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Joined: Jul 2 2009

but wont it put my chain line way out of line  or do you push the cranks as far as needed to the non drive side

Raceface makes a 83mm to 73mm conversion kit. It comes with the shorter sleeve and the spacers that go on the axle. It will make for slightly wider chainline, but that could be good for DH only bike that is used mainly in the high speed cogs.

 

right here............

http://www.universalcycles.com/shopping/product_details.php?id=16131&category=379

gates's picture
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Joined: Jul 2 2009

awesome i will have to look into this

I intentionally bought 83mm Atlas FR's because the Demo has a 73mm bb shell, and 135x10 rear end, but has the same chainline as a bike with a 150mm back end. The 83mm RF cranks withthe RF spacer kit gives a perfect chainline on a Demo. 73mm RF cranks and BB would give a bad chainline be difficult to setup.

Anyway. Does this new bike have a 150mm rear end???? If yes then the 83mm cranks withthe spacer kit will likely give you a favorable chainline.........

gates's picture
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Joined: Jul 2 2009

yes it has a 150mm rear end   is there much work in swaping them over      Did you buy yours from the site posted above

swapping what over?????????? Putting the spacer kit on the old BB???? All you do is change the dust cover, and put the silver spacers on each side of the axle.

If you have it all in Wolfville you can bring it over to my place and we'll gear it up.

gates's picture
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Joined: Jul 2 2009

Thanks dave I will give you a shout if i need some help but i get the idea its pretty straight forward