Shimano external 83...
 

[Closed] Shimano external 83mm BB in 68mm shell

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Can anyone confirm what the difference is between these Bottom Brackets, is it just the plastic tube sealing? If so I'm assuming the cups are the same and I can use my old 68mm tube?

Is it also ok to use a road BB with appropriate spacers?

The reason I ask is because by BB is squeaking and grinding and is due its annual replacement and I have a spare road BB and if no use I can get a good deal on an 83mm.

Any help much appreciated.


 
Posted : 03/06/2015 6:16 pm
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I'm quite sure a road one is out by can't see any reason why an 83mm won't fit as I'm sure its just the tube thats different .


 
Posted : 03/06/2015 6:19 pm
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Road and ntb are different I think the threads are longer on some bb's but as long as it goes up tight then I can't see the 83mm being a problem.


 
Posted : 03/06/2015 8:08 pm
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I put an Ultegra BB into my MTB frame, although I did have the longer plastic tube from the knackered BB which it replaced. Seems ok, will start a thread if it blows up on me.


 
Posted : 03/06/2015 8:54 pm
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I think the thickness of the cup are different on shimano MTB & road.
As Hope BB need 2 x 1mm spacer (on each side) to fit to a road frame.
But just the "normal" spacers for fitting MTB.
(hope use same BB for both road & MTB)


 
Posted : 03/06/2015 10:04 pm
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As Rob says, road BB cups are 1.5mm wider per side than MTB cups, so need thinner spacers to fully engage the splines of the axle/crank arm. Not measured 83mm cups, so can't comment on those.


 
Posted : 03/06/2015 10:51 pm