Algodoo

Good, but you should re-revisit it:

The back wheel slips a lot when accelerating, and it spins like heck. You have to be superhuman to do that. Add more friction and reduce the speed and torque.
The back wheel is clearly untethered to the pedals. add a visual part like a chain made from a polygon that looks like a chain, and at least use a stretched axle to connect the pedals to the wheel (If you can use internal gears to connect it, the pedals should spin in the same direction and go 1.5 or 2 times slower than the wheel)
And the mobility thing is really awkward