my gym has a Concept 2, and that is what I've been using. I have to work into these things slowly, so I am currently doing 5 to 10 minutes at 300 to 500 on the meter. Not sure 300 what, that's just what the thing says. I spin easy for 10-20 min to warmup, then I do a treadmill for 15-20 min increasing speed and elevation once a minute. Then I start doing the more vigorous stuff like rowing, the jogging machines or steppers, and of course, the exercycle. Right now I am base building at more interested in that than intensity (sigh).