I've been using SPDs for the past two weeks and since the first proper ride with them the back of my left knee has been really aching each pedal stroke. The right one is fine but I feel like the pain is stopping me putting much effort in on the left leg so my speed is probably suffering..
It doesn't seem to hurt when standing up to pedal so I'm thinking maybe the seat positioning is wrong (though I never had this problem on flats). It can't go forwards any more (without buying an inline post) which it feels like it may need to as my knee doesn't quite line up with the centre of the pedal axle. Though if this were the case wouldn't it happen with both legs? Any ideas?
edit - it's a road bike if that makes any difference.
Try moving the cleat back slightly, i had bad knees until i did that.
Having always ridden clipless (with CB pedals) with no knee problems, I switched to flats late last year. I tried clipless again recently and my knees played up every time.
Gone back to flats and to be honest I prefer them.
Back as in closer to the heel? It's right at the front at the minute as I've found that to be the comfiest for my right leg. Will try it as I'm almost at the point of scrapping them and using flats to save problems!
Could it be that your seat is a fraction to high? Most people have one leg that is a slightly different length to the other, I found I was over extending when I first tried SPD.
That could also be a possibility that I didn't think of, I raised the seat a little bit when I put the spds on as I found they made my feet sit a bit higher than flats.
Yes, closer to the heel. some people have different alignment one one leg to another. But CB pedals are really knee friendly.
tom - I've often found that switching from one thing to another causes problems. So whenever I can I always phase things in slowly. Be it new shoes, new padals, new cleats, new bike. Just an idea. Might help.
SB