RFX fit and knee pain?

[kotajack]

Getting some knee pain and I am wondering how much a difference 170-175mm cranks make on knee extension? Its only 5 mm and I am thinking thats a non issue but I may be wrong. With the seat so high that I can barely get my leg over it when getting on the bike, I still do not have full extension at the bottom stroke of the pedal. I am running 170 mm cranks. I am thinking with the higher bottom bracket and the shorter cranks that may be my problem. I did not get this pain with a heckler and 175 mm cranks. I have run flats as well as spd and no difference. This rfx rips through rock gardens, no pedal smack, super solid bike. Should I go to 175 cranks, is it possible thats the cause?

[DHRracer]

[QUOTE=kotajack;8561495]Getting some knee pain and I am wondering how much a difference 170-175mm cranks make on knee extension? Its only 5 mm and I am thinking thats a non issue but I may be wrong. With the seat so high that I can barely get my leg over it when getting on the bike, I still do not have full extension at the bottom stroke of the pedal. I am running 170 mm cranks. I am thinking with the higher bottom bracket and the shorter cranks that may be my problem. I did not get this pain with a heckler and 175 mm cranks. I have run flats as well as spd and no difference. This rfx rips through rock gardens, no pedal smack, super solid bike. Should I go to 175 cranks, is it possible thats the cause?[/QUOTE Depending where the pain is one possibilty is that a slacker seat tube angle your knees are not over the pedal spindle. The farther back your knees are the more stress will be on them especially while climbing. Think-doing squats-vs-wall squats(back against a wall knees bent at 90degrees you will feel the difference. You also don't want full extension of the knee try to keep the angle no less than about 15 degrees. Try moving you saddle forward. You may also need to spin a smaller gear than you did on the heckler. These are just ideas by no means the only possibilties

[kotajack]

Thanks for the heads up, I am aware you do not want full extension. I just got much more extension on the heclker. My seat is set all the way back so I will definately slide it foward a bit. Top of the kneecap where quad joins the kneecap. The pain is the same that I used to get on my small bullit. When I went to the medium heckler there was zero pain that is why I think it is a fit problem. Could be getting too old too- haha