I'm new to Bike forums and biking in general. I purchased a mountain bike last year (specialized roadhopper) and spent some of last year and all of this spring & early summer on the trails in Illinois. I did a few organized rides and soon realized I was the only one on a mountain bike so considering the fact that I had been putting in about 150 mi. a week I just purchased a felt F4C. This past week I've been experiencing a great deal of pain on the outside of my right knee right on the epicondyle. Since I never experienced this on my mountain bike is this a fit problem & if so what suggestions do any of you have?

thanks

Need more info

For starters:
Were you fitted by the bike shop?
Do you have clipless pedals?
What kind of pedals do you have?
What is your typical cadence?
Is the gearing different from your MTB?(I am sure it is, but did you go from a triple to a double?)

Ditto what slowandsteady said. More info is needed.

I will speculate however that if you are used to MTB gearing and geometry, that perhaps you are "mashing" in inappropriate gears ratios.

Is the Felt the proper size? Were you fitted by a trained person at the LBS? All that, and gear ratios, too. Proper fit and proper pedaling are key.

It sounds like the seat is at the wrong height. I'd start with lowering the seat a bit. Start off with small adjustments until you find the right spot for you. If that doesn't help try raising it, but it more likely to be a seat that's too high.

Most likely rotation of the shoe is the culprit. Having the heel too far out will cause pain on the outside of the knee. Try adjusting the cleat to move your heel in more.