I don't even know what you're talking about any more, Fuji.

Yeah, you can make bikes hard to pedal, which you're clearly confusing with "a good workout". It's not. You'll be slow, bored, and hurt your knees. And it will be a less effective workout than spinning.

Read up on wattage as a measure of cycling performance. For a cyclist to put X watts into the drivetrain, he or she must produce X watts from their body. This is a pure measurement of energy.

You can generate exactly the same wattage on a MTB or a FG or a geared road bike. The only difference is going to be your speed; the MTB has the most losses, so you get less velocity per watt. This has no impact whatsoever on the wattage produced by the rider, just the speed.

If you feel more tired after a ride on your MTB, it's because you were bored and wanted to go faster, and in order to do that you had to generate more power by increasing your effort level. If you put out the same effort on your FG, you'd generate the same amount of power, and get the same workout.



I think where you are making your mistake is in trying to calculate power based on a constant speed. If a MTB and a FG are both going 20 mph, then yes, the MTB is working harder.

What you should be saying is "if an MTB and an FG are both being pedaled at 400 watts, the FG will go faster... but speed is irrelevant and the workouts are identical."