BB spindle length help
 

I want to try and fit a shimano 600 square taper crank to the 73mm wide shell on my new Gorilla Monsoon. Having trouble figuring out what length spindle to make this work. What’s the brain trust think?


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I believe that the Ultegra 6400/600 cranks used a 113mm spindle for 68mm BB shells or a 115mm spindle for 70mm shells. Shimano makes the UN55 square taper bottom bracket in 73x113mm. That may work for you.

Greg

Concur...BUT..disc brakes(wider rear dropouts) and perhaps fatter chainstays..the 113mm 'may' not be wide enough...AND, if you do need a 118/122/etc..you 'may' have issues with front der having enough travel to get the chain to the big ring...

Yep on disc, and it is a 142mm rear end. It has a pretty big relief on the chain-stay for clearance but all I have is a standard 68mm bb for test fitting.


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Would also be ok running the crank 1x if I can find a polished silver narrow wide chainring to match the 600 tricolor crank.


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As a fan of square tapered cranks, and someone who could help advise you regarding spindles for that application, I have a suggestion.
Use an external bearing bottom bracket and large diameter spindle crankset akin to the way All City suggests the frame can be assembled as a "complete."
Unless you "need" to make this bike work with a 6/7-speed rear cassette, which seems doubtful given the 142-disc rear, I can't imagine how the Ultegra 600 crankset contirbutes to creating a cohesive drivetrain for this bike.

I have an alternative drivetrain ready to go that I know will work but like the ascetic of the 600 parts on this frame. I have the matching tricolor shifters and der to go with it. The gear range will be fine for the purpose I have for it (its 8-speed stuff) so if I can make it work with out a lot of fuss I’m all for it.


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Have you checked yet to see if the clamp for your Ultegra FD will clear the seat tube cage boss in position for the 52t/53t chainring?

have not verified this yet, will work on that.