Belt Drives with Hub Gears and Motors

Which gear systems go with a belt?

Not a derailleur. One cycling site says belts cannot be used with derailleur systems. They rely instead on internally geared hubs or gearboxes.¹

An internally geared hub, or hub gear, keeps the gearing inside the rear wheel's hub. Another reference page calls hub gears a way to change ratios where outside derailleurs won't fit.² A belt bike can also have just one gear. Then there's nothing to shift.

How do e-bike motors fit in?

There are two common types, and they sit in different places.

A hub motor is built into a wheel hub. Wikipedia says brushless hub motors are the most common in modern designs.³ In that design the wheel hub is the motor.

A mid-drive motor sits in the middle of the bike, usually at or under the bottom bracket, where the cranks turn. Wikipedia describes a system where the motor isn't in a wheel but drives the chain.³ Whether a given belt system is approved for a mid-drive e-bike is set by the belt maker and the bike maker. Check your own manual.

Can a belt be used with an e-bike motor?

Wikipedia names belt drive as one way to add electric assist to a pedal cycle.³ That's a general statement about what's possible.

It doesn't mean any belt will do with any motor. Only your bike's manual can say what yours was built for.

Does a mid-drive work with a hub gear?

It can. Wikipedia says the two can be combined. It warns the pairing may need care, since the hub has no clutch to cushion the jolt as the gears pick up the load again.³

That's a general reference point. How shifting is meant to work with the motor on your bike is in its manual.

Does the motor change how the belt is set up?

Possibly. One bike maker's support page says the best tension depends on the specific model, the rider's weight and riding style.⁴ An e-bike's motor adds another reason for a maker to give its own numbers.

For that reason, don't take a tension figure from a different bike. Use the one in your manual. Belt tension explained covers how those figures are checked.

What shouldn't I do?

Don't change the motor settings, swap cogs for ones the maker didn't list, or fit a belt from another bike. Don't try to alter the motor's output to suit a belt either. Where the maker lists approved parts, use those. If a shop offers a different combination, ask whether the bike's maker allows it.

The basics of belt and cog are in the parts explainer.