I've been over-tightening bottom bracket cups for years without knowing

I was putting a new square taper BB into a steel frame yesterday and the drive side cup felt gritty. I checked the threads with a flashlight and saw tiny metal flakes. That's when it hit me: I've been cranking them down way too hard, thinking 'tighter is better'. The spec is only 35-50 Nm, but I was probably hitting 70 or more with my long wrench. No wonder I've had a few creaky ones that needed re-greasing after a couple weeks. How do you guys judge the right feel when installing cartridge bottom brackets?

3 comments

3 Comments

kevin2189d ago

Oh boy, that's exactly the kind of wake up call we all need sometimes. @tyler_burns66 is spot on about a beam style torque wrench being a good cheap fix for this. I grabbed one a few years back for under fifty bucks and it's saved me a lot of headaches. The key thing I've learned is to feel for the threads starting to bind up before you even get to torque. If it's smooth and the cup goes in easy, that's a good sign you're not fighting cross threading or dirt. Those metal flakes you saw are a clear sign you were putting the frame under a lot of stress and I bet some of those creaky ones were the shell deforming just slightly from the over tightening. It's a shame it took me a damaged frame to learn this lesson.

palmer.jana2mo ago

Oh man, this is a huge wake up call. I totally did the same thing for the longest time, just reefing on it until it felt "solid." I never even thought about a torque wrench for a BB. Seeing those metal flakes would freak me out. Now I'm wondering how many frames I've stressed over the years. Gonna dig out my torque wrench next time for sure.

tyler_burns662mo ago

Yeah, that gritty feel is the worst... I finally bought a cheap beam-style torque wrench just for BBs and headsets. It's not perfect, but it gets you in the ballpark.