Personally,
I have had ACL replacement surgery after a few years of rugby and jumping out of helos and C130s. My knees are shagged for the most parts, but cycling is the only thing that works for me. My old fixed (RIP - friggin cabbies) and my Surly have never lead me wrong. Fixer is spot on: find a gear that works; who cares if you aren't rolling a 53:12 (who the hell can? I'd piss myself...). It is about a good experience.
And OTS-I'd buy one of those patches...not if it was bagsized though. I'd put it dead-center on my mesh half-shirt.