Bicycle Mechanics - Shimano BB/Torque Wrench question

We have Shimano splined BB cups. I have 3/8" drive (bar and pointer) torque wrench. I have a Shimano splined BB tool. I have a 15" adjustable wrench.

OK, so I can use a skewer to hold the BB tool in place while I tighten things with a big adjustable wrench and guesstimate the torque.

My question is how can I use the torque wrench without resorting to the somewhat dicey method of holding it in place in the shallow splines of the adjustable cup with one hand while I torque to 400 in-lbs+ with the other?

I torque the BB successfully by being careful. Still I feel I am just one careless moment away from damaging the cup splines.

I have searched for a 32 mm crow's-foot (32mm being the size of the hex faces of the BB tool). No joy. Park makes a 32 mm crowfoot but it is octal only not hex sided.

Is this how an LBS does it?

Mike Sakarias
Juneau Alaska

At our shop we use the torque wrench to put them in just like you described. One normally doesn't need to hold the tool in with a skewer or anything as the bb should go in easily by hand then the final "snugging" can be done with the wrench. Try using your left hand on the head of the torque wrench to push it into the bb and turning the wrench with your right hand. The torque is not all that much and by the way Barnetts manuals show that the torque range is from 260 in/lbs to 350 in/lbs not to 400.

-Ryan

There are spline cup tools that fit both 1/2 inch and 3/8ths inch ratchets. If you use a crows foot you will have to figure out the extra lengths effect on your torque reading.
Based on trying to remove BB cups, as long as you keep the tool straight, you are very unlikely to strip out the splines even on one of the cheap plastic cups. It is possible but you need a long lever to do it.

Ok, thanks for the confirmation on technique.

As for the torque, the Shimano specs ("Front Drive System" info sheet) that came with the crankset say 35-50 Nm (435-608 in-lbs). When I have used a torque wrench, I've aimed for the lower value, which seems to be about as far as is convenient to go anyway. Six hundred in-lbs is quite a torque. I don't think I'd want to try to go that high without a more secure arrangement for for the tool in the adjustable cup.

AAhh, thats only fifty foot pounds, look at my sig. That torque wrench was five feet long.