How many miles per hour can a normal bike go?

Answer 1

Depends on the details of the question.

There is a technical limit set by bike/rider interaction, what gearing ratio, wheel size etc the bike has, and how fast the rider can turn the pedals.

Assuming an average bike build and average pedaling skills, you get a top speed around 25-28 mph(40-45 kph) before "spinning out", the speed where the pedals turns too fast for the rider to be able to add any more power.

Now, doing 25 mph on a mtb is quite taxing. Wide, knobbly wheels, upright riding position etc. There's a lot of air drag and rolling resistance.

On uneven, soft surfaces it becomes even worse.

A realistic average is about half.

But maybe you're descending a hill. Hitting 40 mph (64 kph) downhill is easily doable.

On courses designed for speed, riders can go considerably faster, say 70-80 mph on gravity alone.

Answer 2

A normal bike can typically go at speeds between 10 to 20 miles per hour, depending on various factors such as the terrain, rider's skill level, and effort put into pedaling.