Bought a bike on FB marketplace and took it out for a ride , went uphill and the crank spun off (wasn't install properly ,common issue with people installing Shimano cranks apparently)
When it comes to buying a new one , what are the numbers that relate to the size of the axel etc? Do I need calipers and measure through the bottom bracket ?
by SecretNinjaDude
1 Comment
you have to count the number of teeth in there and measure the circumference of the crank arm. Then there is a sheet from Shimano from which you pick the part with the closest match.
JK…
Actually, the Shimano crank arms with hollowtec are standardized. You pretty much only need to know the length of the crank arm, measured from the center of the bottom bracket axle and pedal axle, but you should also find it written on the crank somewhere. Typically 170 or 175 mm or so.
The spacing on the bottom bracket axle is done with plastic spacers, which probably still are there. The crank is preloaded onto the bb axle with a plastic screw. Is the plastic screw still around? The preload has to be enough to remove play in the axle, but not tighter than that. The crank is then secured with 2 bolts
EDIT: By standardized I mean that they really all fit. Deore, SLX, XT, XTR, probably also some road cranks.