Been riding a single speed all this year so far, my first. 48/15 ratio. I figured that would be fine as the MTB I was riding all of last year had a 52 tooth outer (?) chainring and i never got out of top gear on it cept to climb. I mostly commute with some pleasure riding along the lake or what have you. I like to go fast, I think what's killing my knee is the starts ... it's always a race and since I live, work and play downtown there's a lot of stops and starts.

My question to you all is, how messed up are your knees and what can I do, what do you do, to keep injury to a minimum? I don't really want to go lower on the gear ratio, I like going fast. I think the only reason I might go lower would be to learn catwalks
I'm gonna be 30 this year. I come from a background of skateboarding, snowboarding, bmxing and otherwise being hard on my knees. This is the first year that I'm taking cycling kind of seriously, it's fun, it gets me to work on time, it's practical and I have something to obsess over
I would like to do it forever, I don't want a bum knee to keep me from biking or hell, walking comfortably.

Also, it's only one knee .. my right, and it really only hurts when resting, like if I'm sitting at my desk all day or laying in bed/couch whatever. Is this normal kind of strain for biking? Never hurts on the bike, so I have been forgetting about it and going for broke on every ride :/