[simonDyna]

The 34t front belt pulley will give a greater theoretical top speed (providing you can pull it) less acceleration and lower rpm for any given speed.

It will allow you to spend longer in first gear because it can now pull a few mph more than it did originally. This may feel like greater acceleration because you spend longer going through the gears or possibly achieve a higher speed before shifting.

You have gone from a secondary drive of 32/70 to 34/70. Each time the front pulley completes a full circle the rear does 0.48571 revolutions. Previously it completed 0.45714 revolutions.

The amount of teeth on the belt and its relationship to the gearbox are null and void in this instant. Even if the rear pulley was six inches away from the front pulley or six feet away from it, it will still rotate at the same rate of 0.48571 revolutions per one full revolution of the front pulley.

As for power, you still have the same amount of power that you had before. Whether is is now utilised as effectively is a different matter.

If you had put a bigger pulley on the rear, you would get the effect you describe but again, no change to the power.

The key to gearing is looking at the driver pulley and the driven pulley. If in doubt, look at a kids mountain bike. They give a very simple example of 1st all the way through to 15th. First has a small driver sprocket and large driven sprocket. 15th is the opposite with a large driver and small driven.