When setting up your bike

1) are you getting a nice extension in the leg at the bottom of the pedal stroke (knee relaxed at the bottom, not locked out)

2) When your foot is on the pedal at 3-9 Oclock, is the knee over the axle of the pedal? Check this with a plumb line.

3) Resistance - how much resistance are you using, does it feel like you are mashing the pedals. Are you adding too much when the instructors calls for it. What types of bikes are you using? The newer Schwinn bikes have this red lever so you press down on the break (instead of pulling up) and often the red lever and the resistance knob "lock" into each other, so you end up with A LOT more resistance than you mean to have. it means just giving it a jiggle to make sure the resistance knob is moving the way it should.

4) clipless vs baskets, do you feel the pain with one over the other?

Thats all i can think of...

let us know how it goes!

Hannah