OK, so I installed a Shimano Ultegra 6500 Octalink BB on my "project bike". When I tightened it to Shimano's recommended torque (in the mid-range), the spindle got noticeably stiffer and harder to turn.

I contacted my old bike mechanic instructor, John Barnett, at the Barnett Bicycle Institute in Colorado Springs and this is what he said:


"We have found the top end of Shimano's recommend torque range to both be beyond the strength capacity of many individuals, and to be problematic in regard to creating a risk of deforming the aluminum cup splines on models such as the BB-6500.

......

Our published spec for the 6500 is the same as Shimano's lower value. I'd stick with what I said regarding relying on Loctite and sticking to the minimum torque (for the reasons I previously stated). So we recommend going with the 435in-lb value, with Loctite 242 used on the threads.

......

The binding problem is previously unheard of.

Assuming you rule out things like mismatched parts or cross-threaded parts, As a means of diagnosis, I would suggest:

1. Loosen the cup fully and see if the binding goes away. If not, the BB assembly is bad.
2. If the binding goes away, try installing the cup at 5ft-lb (60in-lb) increments (i.e., to 5ft-lbs, then 10ft-lbs, then 15ft-lbs, etc). At each tightening torque, inspect for the binding. Look for whether the symptom occurs suddenly, or whether it builds incrementally. If suddenly, at what torque level did it show up?

Then let me know what you learned, and we can take it from there."