Originally Posted by
TimothyH
Extremely interesting.
The Enduro TorqTite bottom bracket has angular contact bearings and the compression plug is used to set bearing preload. According to Enduro the stainless version gets only 3Nm. That's not much.
I'm thinking that tightening the compression plug again to keep the crank arms on tightly might cause too much bearing preload. I'd hate to decommission an expensive part like the TorqTite.
Do you think the Sugino crank arm pinch bolts don't hold the NDS crank arm securely enough or is this by design? My guess is the latter since it is in the instructions. What is the plug made of? Is there a torque spec on the plug?
-Tim-
Hi Tim, The plug is metal, and is supposed to be tightened very tight initially to make sure the crank arms are in contact with the bottom bracket face. Like on the Shimano system, I tighten the plugs by hand until the crank binds a bit, then release the tension on the plug until the cranks rotate freely and then tighten to torque spec the crank bolts. This releasing before tightening the crank arm bolts releases any undue bearing load and the cranks spin easily. This way of doing it has always resulted in a solid system on the Shimano cranks no matter whether I retightened the plug or not. I think the same approach is correct on the Sugino system, except that you do need to re-tighten the plug after you tighten the crank bolts. I think it will be ok after doing that, but it wasn't really necessary for the Shimano. There is a torque spec on the Sugino plug in the instructions, it is pretty high to initially tension the arms. I don't have the sheet with me right now so can't tell you the exact number. I think it is high because as I have experienced, the crankshaft is a snug fit into the bottom bracket and the tensioning by the plug really is needed to make sure the chainring side is flush. The crank arm bolts are 14-16 nm I believe, similar to the Shimano. I don't think there is any inherent problem with the system, so don't take my comments to mean I feel it is subpar. Interestingly, even thought the non-drive side crank arm had move away from the bottom bracket a bit, the chainring side hadn't flopped around at all. I was doing some intervals and didn't feel a thing but just happened to look down and see a small gap on the non-drive side.