I ride 48/17 now, first started riding fixed on 48/19.
I don't find 48/17 to be any strain on the knees now. They did hurt a little at first when I was mashing, but I did some leg work at the gym and once I was riding with my muscles instead of trying to use gravity to force the pedal down the knee strain went away. In my very unscientific opinion I think one of the quickest ways to get knee problems is to push a gear bigger than your muscles can handle - you're always going to get the muscle burn when you're tired, but it shouldn't hurt to push.
Anyway, most hills in London I'm quicker up than roadies with gears. That said, there are hills I know I couldn't do. I don't know which one West Hill is (I can find it on a map, I just can't picture it), but some hills around Highgate I can manage okay, and one or two are difficult. Last time I went up there I lost momentum near the top thanks to someone pulling out of a side road, and couldn't get started again and had to walk the last 100 yards or so to the crest.
Along similar lines - I went out on my new (to me...) road bike for a big ride with a roadie friend's club couple of months ago, and there were hills that I was struggling even with a granny gear to fall back on. Some were short and very very sharp, but there were a couple of killers that were several miles long. I think I'd fare better the next time - first long ride I'd done, really - but I didn't see me making the whole 50 on a fixie up and down those hills. Apparently the guys in the club who ride fixed have a separate route to follow to avoid the worst hills, so it's not just me who thinks that...
I ride 48/17 now, first started riding fixed on 48/19.
I don't find 48/17 to be any strain on the knees now. They did hurt a little at first when I was mashing, but I did some leg work at the gym and once I was riding with my muscles instead of trying to use gravity to force the pedal down the knee strain went away. In my very unscientific opinion I think one of the quickest ways to get knee problems is to push a gear bigger than your muscles can handle - you're always going to get the muscle burn when you're tired, but it shouldn't hurt to push.
Anyway, most hills in London I'm quicker up than roadies with gears. That said, there are hills I know I couldn't do. I don't know which one West Hill is (I can find it on a map, I just can't picture it), but some hills around Highgate I can manage okay, and one or two are difficult. Last time I went up there I lost momentum near the top thanks to someone pulling out of a side road, and couldn't get started again and had to walk the last 100 yards or so to the crest.
Along similar lines - I went out on my new (to me...) road bike for a big ride with a roadie friend's club couple of months ago, and there were hills that I was struggling even with a granny gear to fall back on. Some were short and very very sharp, but there were a couple of killers that were several miles long. I think I'd fare better the next time - first long ride I'd done, really - but I didn't see me making the whole 50 on a fixie up and down those hills. Apparently the guys in the club who ride fixed have a separate route to follow to avoid the worst hills, so it's not just me who thinks that...