Originally Posted by
McBTC
Based on your numbers and going with 120° as what is required for no issues (not positive about this number but, using it as what is needed to accommodate what has become the industry standard of 175 mm cranks), I'm guessing that ~115° might be what's needed to feel comfortable on 165 mm cranks... Just playing with numbers as there is no information that I have been able to find on this issue. I have read about an implant that was designed specifically to accommodate a greater ROM but the results seemed to be inconclusive. Dr's seem pretty happy with achieving at least 90° for their patients and this amount certainly increases the quality of life for any in need of a new knee but that amount is limiting when it comes to cycling. Seems like shooting for at least 145 mm cranks should be a reasonable objective --e.g., by the math above, getting to ~105°.
I think your numbers are good, at least a match for my physiology. I was riding 138's for awhile but swelling, stiffness and a little pain would happen after a slow 15 km ride. Early on, I optimistically bought a 145mm Cobb crankset for my good road bike but I know I'm not going to be able to put them to use until I claw back that extra 10 degrees or so. Even then, I think platform pedals will always be a part of my riding experience from now on.