Any doctors on board? I have arthritis in both knees...first diagnosed about 3 yrs ago (I'm mid 40s). I cycle as much as I can, and jog occasionally and also walk 5-6 miles a day. Cut down on jogging and playing footy, but when I do, my knees hurt for a day or 2 afterwards. I try to do non-weight-bearing stuff, so cycling doesn't make them hurt. Neither does rowing (I have a machine). I met an older guy (60+) out cycling, walking his bike along country lane. Asked him if anything wrong, and he said it's just me knees, arthritis you know, just giving them a rest. I said "Ooh, I've got that", and he took a sharp intake of breath, pursed his lips and said ominously "It gets worse, you know"... so, how bad does it have to get before i can get some new ones put in?