Do not ever buy a hub made by Surly. I will lose my mind if I try to understand why anyone at this company thought that a 5mm allan bolt is sufficient to hold a rear fixed wheel in place. First I had angular contact bearings that were impossible to adjust, and now I have this obscene axle bolt that stripped the first time I tightened it. I used a torque wrench and watched it strip way before I reached the torque specified in the instructions (35-40 ft/lbs). I have lost all hope for this company, and just wanted to warn other people that this hub is worthless.