For a vintage Zeus crank set with a square-taper, cotterless spindle, what is your advice for checking torque after servicing spindle bearings and reinstalling all bottom bracket components?
I've read Jobst Brandt's treatise on the subject and it seems to make sense. Lightly greasing the taper surfaces and installing the crank arms to 30 foot pounds of torque seems reasonable. What is confusing is whether to check arm tightness later, after many miles of riding.
Brandt, with an engineering degree from Stamford, points out that crank arms actually creep up the taper from use, unloading the torque on the crank-arm retention bolt. If one checks the bolt after use, one will find that the bold has lost its load due to crank arm creep. Applying more torque to re-tighten the bolt will result in the crank arm creeping further up the taper, eventually rendering the arm useless as it moves to the furthest point up the taper.
My bike's 46 years old with the cranks installed in 1971. I've never had any questions regarding this issue in the past. However, last September, the left crank arm cracked unexpectedly with no prior warning at the point where the mounting bolt inserts . Probably just metal fatigue, but now I'm paranoid and am stressing out about this crank torque issue.
Extensive internet searches just muddle the issue even further.
Advice? Suggestion??
I've read Jobst Brandt's treatise on the subject and it seems to make sense. Lightly greasing the taper surfaces and installing the crank arms to 30 foot pounds of torque seems reasonable. What is confusing is whether to check arm tightness later, after many miles of riding.
Brandt, with an engineering degree from Stamford, points out that crank arms actually creep up the taper from use, unloading the torque on the crank-arm retention bolt. If one checks the bolt after use, one will find that the bold has lost its load due to crank arm creep. Applying more torque to re-tighten the bolt will result in the crank arm creeping further up the taper, eventually rendering the arm useless as it moves to the furthest point up the taper.
My bike's 46 years old with the cranks installed in 1971. I've never had any questions regarding this issue in the past. However, last September, the left crank arm cracked unexpectedly with no prior warning at the point where the mounting bolt inserts . Probably just metal fatigue, but now I'm paranoid and am stressing out about this crank torque issue.
Extensive internet searches just muddle the issue even further.
Advice? Suggestion??