I've been riding fix gear for 42 years. Had CP (chrondomalcia patellae for 40; caused by a combination of probably being prone to it but not knowing, increasing my level of training and speed very fast (coming from rock bottom after a major head injury to fast enough for an early season race in a few weeks), not stretching my hamstrings, riding with cold knees and switching from 168 cranks to 175 and taking that long cranked bike (my race bike) for a March 100 mile training ride first time on it. In other words, breaking just about every CP rule there is.

I've kept riding fixed. If I do the CP regime and keep my rule-breaking down to a minimum, I can do just about anything I want on the fix gear. Yesterday I rode the "Worst Day of the Year" ride fixed. 2000' of climbing. Twice up to Skyline Blvd west of Portland. 2nd climb had us doing 476' in 1.18 miles (7.6% ave with an 11% max. I did it on a 42-17. Hard, yes. I had to pace myself. Glad I had a really good fitting and working bike and shoes/cleats because I was pulling/pushing hard. That evening, I could feel my knees a little. Yes I pushed it. Took one aspirin last night. I feel them still now. but I will probably ride fixed in town tonight easy. (I doubt the rest of my body is up to doing more!)

I've been doing rides like this sporadically the entire time I've been riding fixed. 100,000 miles. (I used to ride the same gear up Juaquim Miller over Oakland. Rode Mt Diablo in that gear also. Cycle Oregon 4 times. (Yes, I did bring extra cogs and changed them multiple times each day.)

Ben