Hi,

Just put on my new crank arm (new BB too) and was wondering if I tightened it down enough - don't have a torque wrench but I was using a 150mm socket wrench. I think the drive side is on OK as the chainline looks to be pretty good.

Thanks

Daven

1. What kind of bike? That looks like it's sticking out a bit far to me. I'm wondering if you have a BB that's designed for a 73mm frame in a bike with a 68mm bottom bracket shell. Do the pedals look like they miss the chain stays by an equal amount?

2. Crank arms are something that I use a torque wrench for. 150mm is pretty short. Try to imagine a 30 pound weight hanging off of the end of a 12 inch (305mm) wrench. That's the right amount of torque.

The BB is a 68mm cartridge type and came with a 122.5mm spindle (gives me the correct 47.5mm chainline). Will give it a bit more welly then

Thanks

Daven

Ok having measured it the drive side crank arm is actually 3mm further away from the chainstay than the non drive side arm (which was the one pictured). I have tried to tighten it some more with no luck. Is this normal / a problem?

Hmm also looking at it the drive side bottom bracket looks like it is sticking out about 1mm. I guess I need to loosen the plastic side and then reseat the bottom bracket. Will do this then reinstall the cranks!

Thanks

Yes the drive side needs to be tightened before the non drive side.

The crankarm looks like it's going on the BB spindle far enough, but I doubt you'll get it torqued down enough. That wrench is much too short. As Retro said, 300 to 400 inch-pounds is correct. Anything less and you run the risk of the crankarm loosening and being ruined.

Torque values and concepts: https://www.parktool.com/blog/repair-...s-and-concepts

Thanks guys, I have now removed the crank arms (think I may have damaged the drive side beyond saving - I left the round thing in the crank extractor -I think it is meant for various crank types - and it bent some of the metal at the top of the crank taper which later fell out - not impressed, but at least they weren't expensive!)

However they are now on and the bottom bracket is flush on the drive side and the arms are within 2mm of each other in terms of distance from the chain stay. Also it was now tightened with a longer wrench.

Will try the cranks out slowly to see if they are still ok, otherwise it is back to the shop!

Thanks

Daven