I've been cycling consistantly for about 4 years. I've done a 6 month tour, and last summer I cycled 2 weeks in the Alps. All this cycling has been done in clipless Look or Shimano SPD pedals without any knee pain whatsover. About 4 months ago, I bought an old mtn bike for commuting and fitted platform pedals for their practicality. Unfortunately, ever since, I've had pain in both my VMOs, particular my left VMO. Due to the fact that I noticed I was cycling with my midfoot on the platform pedals, I have since fitted cages to let me spin more and use the ball of my foot, like on cleats. The pain persists. Also, I've also noticed that my knee cracks virtually everytime I straighten it. I'm not sure if this is linked, but I know this wasn't the case before the pain started. The pain isn't debilitating, but it's bothersome enough and I worry that I could be doing longer term damage to the joint.
Although I'm open to any suggestions on remedying the issue, I'm actually more curious to find out if other people have had such problems when changing 'back' to platform pedals.