Join Date: Oct 2002
Location: Annandale, New Jersey
Bikes: 2014 Surly Steamroller, 1989 Nishiki Altron
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Use the right tool for the job. The bottom bracket won't work, chainline will be way out of whack.
An external mtb crank is setup for 68/73 bb cups and uses the bottom bracket spacers included with said bb and the spindle length speaks for the 68/73 setting so you would have to space the bottom bracket out because the 50 tooth will hit the frame and if it doesn't will be close that if it doesn't it will be so close the if the chainring warps, it will hit. When you space that bottom bracket out, there won't be enough spindle showing to clamp down on. IF the bottom bracket spec on the frame is 73 it won't matter since it won't work, it will be too wide.
Last edited by Dannihilator; 07-07-13 at 08:20 PM.