Odd one this. I have a bike that has a bottom bracket that spins freely in the normal forward direction, but is harder to turn in reverse and has a tight spot in it whilst doing so. I have removed the chain to eliminate the free hub / derailleur as a cause. I have also spun the crank using the crank arms to eliminate a pedal issue. So it is definitely a bottom bracket issue. It is a square taper type. Never seen anything like this before. There is a marked difference in the freeness of roatation in different directions. The crank arms are not bent and neither are any of the chainwheels. The axle does not seem to be bent either as there is no noticable lateral movement of the crank arms when turning.