I havent been able to do either chin-ups or pull-ups in a while since my left wrist just doesnt seem to want to heal. It's either the tendon or the ligament on the outside (little finger side) of the wrist, slightly towards the top of the hand. Complained like a b!tch when I last tried to do some actual pull ups. However, it does not hurt when I do them from two parallel bars. I've been trying to give it time to heal up, but soft tissue injuries take forever to heal for me. This wrist thing has also prevented me from doing normal pushups, however I can do them fine if I do them on my knuckles. It's sort of odd and very annoying
The only access I have to something like parallel bars is on the service truck at work. There are two ladders on the ladder rack, the inside rails are about 30" apart. Last week, after my shift was over, I did nine reps. From full slack (only muscle tension being that to hold onto the rails and bending my knees upwards to keep off floor) to fully up (chin a few inches over the top of the rails). Not bad considering it was after about 11 hours of roofing and I weigh ~220lbs when you include boots and most of my winter work clothes.
If I did them fresh (ie before work) on something with the rails closer together, I imagine it would be significantly higher. Also, I dont know how doing it from parallel bars compares to pull-up/chin-ups. I'm going to wait at least another month before trying them again, though.
BTW: anyone have a link to one of those rep charts that show "X reps at A weight = Y reps at B weight"? I've lost a lot of weight in the last year, and I'm wondering what my current muscle condition would yield if I were at my target weight, which I should be at in another couple months.