Originally Posted by
HillRider
"Crank retention problems" usually mean the crank arm itself is damaged. That is the square taper hole in it has been hogged out or distorted because the crank bolts (or nuts in this case) weren't torqued sufficiently tight and the arm moved on the spindle. The crank arms are aluminum and the spindle is hardened steel so guess which gets damaged? And, once this happens, the crank is not repairable by any reasonable method.
There is nothing inherently wrong with nutted bottom brackets although they tend to be cheaper, low-line ones. Installed properly and the nuts torqued sufficiently, they will hold the crank arms as reliably as any other type. That assumes the crank arm itself is in good condition.
Well the installed version of that crank that was working fine just went into crank retention mode. Should I throw another left crank on there and risk destroying it if the BB taper is bad like the 3 I destroyed on the other bike or should I just change out both the BB & crank. FWIW, this is an old Raleigh Super Grand Prix 1977 I believe, Raleigh SR cranks. This is the only installed set of 165mm cranks I have, I may have another uninstalled set somewhere, but the 165mm cranks were to small for me anyway. This is an undersized frame for me by about 4 inches, and even with the 165mm cranks I have a front tire toe strike issue with my size 13 feet.