Comparison of Bafang mid-drive motors

The three Bafang mid-drive kits fit into a single table, and yet they don't answer the same question. The BBS01B assists a city bike without changing its nature, the BBS02B covers most conversions, the BBSHD is for riders who carry heavy loads or climb often. This comparison lines up the specs, then explains which gaps actually matter.

The spec sheet, field by field

Seven fields, identical for all three models, taken from the manufacturer's documentation. None is left blank here: Bafang publishes every one of these values for the BBS series.

The three gaps that really decide

1. The bottom bracket, ahead of everything else

A BBS01B and a BBS02B share the same footprint: 68 to 73 mm, with long-axle versions in 100 and 120 mm. The BBSHD widens the range up to 100 mm and also offers a 120 mm version. On paper, it is therefore the most accommodating of the three.

In practice, the opposite happens. The advertised width says nothing about the bulk of the housing, and the BBSHD's is markedly larger. On an old steel frame, the question doesn't even arise; on a modern full-suspension bike, it is often the BBSHD that refuses to fit while a BBS02B would have gone on without any trouble. In other words, the compatibility range is there to rule models out, never to confirm one.

2. Controller amperage, more telling than watts

15 A, 25 A, 30 A: these three figures sum up the character of the three kits better than the 250, 750 and 1000 W on the label. The maximum current decides how sharp the pull is and how well the motor holds a long climb without fading.

It also sets the demand placed on the battery, and that is the item riders discover too late most often. A pack unable to deliver 30 A continuously will throttle a BBSHD without any warning light coming on: the motor will feel short of breath, and the wrong component will get the blame. Choosing the motor first and the battery second avoids this trap.

3. The sensor, identical across all three

All three kits read the rotation of the crank, never the force applied. At a given assistance level, the motor pushes the same way whether you press hard or barely pedal at all. That's effective for moving forward without effort, less refined for recreating the feel of a purely mechanical bike, and it applies just as much to the BBS01B as to the BBSHD.

This shared trait has a direct consequence on the drivetrain: torque arrives all at once, often right when you shift gears. The guide to the two sensor types details what each one feels like, and the comparison with a torque-sensor kit shows what the other approach offers and costs.

Our pick by profile

What the table doesn't show

Three factors fall outside the spec sheet and still weigh heavily on the decision:

• The bike's legal status. Only the 250 W version of the BBS01B, whose assistance cuts off at 25 km/h, keeps the vehicle in the pedelec category. The regulatory rundown is worth reading before the purchase, not after.
• The real cost of the install. Battery, display, gear-shift sensor, and sometimes a replacement drivetrain: the final bill always exceeds the motor's price. Details are in Bafang motor prices.
• The condition of the donor bike. A sound frame, effective brakes and a recent drivetrain make the conversion worthwhile. On a tired bike, the kit only shifts the problem onto the wear parts.

Going further, head to head

• BBS01B versus BBS02B — the first arbitration, roughly a hundred euros apart.
• BBS02B versus BBSHD — the most searched duel in the range.
• Bafang or Tongsheng, cadence versus torque — the only real alternative in feel on the conversion-kit market.