PaulRivers

Sure thing, I used to help friends in college, again and again that was the problem - hope it helped. :-)

These are the major physical bike related problems from worst to less worse:
- Mountain bike with rear suspension - it will eat your power alive (unless it's fairly expensive rear suspension). Most people don't have rear suspension though.
- Knobby tires - they're slower and less grippy on the road, contrary to what people intuitively think. This is more common, but easier to fix - people in college could be convinced to buy new tires, whereas buying a whole new bike was out of the question.
- Your brake pads are rubbing. Lift up whichever end of the bike the tire is on that you want to check, and spin the wheel in the direction that does not cause the pedals to spin. If the wheel doesn't rotate more than 2-3 times, your brake pad is most likely rubbing (or your wheel has something seriously wrong with it in the bearings, but that's pretty rare). Usually if you give it a good spin it should spin at least 8-10 times without coming to a stop.

These are the usual not-actually-the-bikes-fault problems:
- Your seat it to low. Relatively easily fixable, and importantly - free. :-)
- You're severely out of shape (lol). But the cure to this is just - more biking! :-)

If your feet were on the ground while sitting on the seat, it's almost certain your saddle was to low. Hope that helped for you!