Bafang Motor Conversion: What You Need to Know Before Installing

Byhenry

In this hub: Conversion Kits & DIY Hub — browse the recommended reading order.

Bafang mid‑drive kits are popular for one reason: they turn an ordinary bike into a strong hill climber. But Bafang conversions also have a few predictable “gotchas” (bottom bracket fit, chainline, drivetrain wear, and wiring). This guide helps you check fitment, choose the right setup, and avoid the common problems before you start.

Quick answer: is Bafang right for you?

Choose a Bafang-style mid‑drive if:

  • you ride hills or carry cargo,
  • you want a natural “bike-like” feel,
  • you’re okay doing more DIY (or paying for a shop check).

If you mainly ride flat routes and want an easy install, a rear hub kit can be simpler.

Bafang vs hub kit (when Bafang is overkill)

If your route is mostly flat and you just want light assist:

  • a rear hub kit is often cheaper, simpler, and lower maintenance.

Bafang shines when you need torque on climbs or you want to haul weight.

Pre-install checklist (copy/paste)

  • [ ] BB width/type confirmed (threaded vs press-fit)
  • [ ] Enough chainstay clearance for the motor housing
  • [ ] Battery mount plan (triangle preferred)
  • [ ] Brakes are strong (or upgrades planned)
  • [ ] Fresh chain/cassette if current parts are worn
  • [ ] Correct tools: crank puller + BB tool + torque wrench

Bottom bracket standards (plain English)

  • Threaded BB: common on many bikes, easiest for mid‑drives
  • Press-fit BB: common on some newer frames; may require adapters and can be more finicky

If you’re new to this, a threaded BB donor bike is the smoothest path.

Battery voltage planning (what most riders choose)

Many Bafang-style systems commonly run at:

  • 36V for lighter assist
  • 48V for stronger hill response

The key is matching your controller rating and using the correct charger for the battery.

Installation tips that prevent 80% of problems

1) Clean the BB shell and grease threads (where appropriate)

Grit and dry threads lead to creaks and incorrect torque.

2) Tighten the motor mount properly (and re-check)

Mid‑drives can loosen slightly after the first rides. Re-torque after 10–20 miles.

3) Protect chainline early

If your chainline looks extreme in the middle gears, fix it now—don’t “hope it settles.”

4) Don’t ignore shifting technique

Mid‑drives punish “full power shifts.” Easing off is the cheapest drivetrain upgrade.

A simple maintenance schedule for a Bafang build

Weekly (or every 50–100 miles)

  • Check chain lube and chain wear
  • Inspect battery mount tightness

Monthly

  • Re-check key bolts for torque
  • Inspect cable rub points and connectors

Every 500–1,000 miles (depending on riding)

  • Measure chain wear; replace before it kills the cassette

This keeps your conversion feeling “tight” instead of gradually turning into a rattle box.

Step 1: Confirm bottom bracket compatibility (most important)

Most Bafang mid‑drives are designed around common threaded BB shells.

Check:

  • BB shell width (68mm/73mm common)
  • Threaded vs press-fit
  • Clearance at chainstays (shape matters)

If your bike is press-fit, you may need adapters—and fit can vary.

Step 2: Choose the right “power level” for your use (US context)

A lot of U.S. e‑bike rule discussions reference the Class 1/2/3 framework and motors under 750W. PeopleForBikes class overview

Practical guidance:

  • Commuting + moderate hills: “mid-power” setups often feel plenty
  • Cargo/heavy riders/steep hills: stronger setups, but watch braking and drivetrain upgrades

Remember: power without control upgrades (brakes/tires) is how bikes get sketchy.

Step 3: Plan for drivetrain wear (mid‑drive reality)

Because a mid‑drive uses your chain and cassette:

  • chains wear faster,
  • cassettes wear faster,
  • shifting technique matters.

The single best habit

Ease off power while shifting. Even half a second helps.

Budget tip: if your drivetrain is already worn, replace it before conversion so you’re not diagnosing “conversion problems” that are really old parts.

Step 4: Chainline (what makes a Bafang build feel smooth)

Bad chainline causes:

  • noise
  • chain drops
  • rapid wear

How to check it

  • In the middle cassette gears, the chain should be fairly straight.
  • If the chain angles hard, plan chainring offset/spacers.

Many successful builds use an offset chainring to improve chainline on wider rear triangles.

Step 5: Battery + wiring (do it safely)

Battery sourcing and charging

CPSC recommends being present when charging, using the correct charger, and not charging while sleeping. CPSC charging safety

CPSC has also issued warnings about certain battery products associated with fire hazards—avoid sketchy packs. CPSC warning example

Cable routing checklist

  • Keep cables away from crank and chain
  • Avoid tight bends at connectors
  • Add protection where cables rub the frame
  • Use drip loops if you ride in rain

Step 6: Helpful add-ons (worth it on many Bafang builds)

  • Brake cutoff sensors (safer stops)
  • Gear sensor (reduces drivetrain shock during shifts)
  • Better brakes (pads/rotors or full upgrade)
  • Puncture-resistant tires (commuter reliability)

Step 7: First ride setup (avoid the “wow it’s jerky” problem)

Start with:

  • low assist levels,
  • gentle throttle behavior (if applicable),
  • and smooth acceleration.

Then increase assist only as needed. This often improves real range and makes the bike feel more controlled.

Display and settings (keep it tame at first)

Most controllers let you adjust:

  • assist level strength
  • start current (how “punchy” it feels)
  • speed limit behavior (depends on controller/display)

If you’re building a commuter:

  • start conservative,
  • prioritize smooth starts,
  • and increase assist only as needed.

A smoother setup usually improves both control and real range.

Brake upgrades (what’s “enough”?)

At minimum, you want brakes that can:

  • stop hard without fading,
  • stay aligned,
  • and feel predictable in the wet.

If you’re on old rim brakes or tiny rotors, plan upgrades before you add lots of power.

Common issues and fixes

| Problem | Likely cause | Fix |

|—|—|—|

| Motor creaks under load | Mount not tight | Re-torque lock rings/mount |

| Chain drops | Chainline issues | Offset ring/spacers; check derailleur |

| Poor shifting | High load shifts | Ease off; consider gear sensor |

| Random cut-outs | Loose connector | Inspect and secure wiring |

| Overheating feeling | Too high assist on steep climbs | Use lower gear + moderate assist |

Where you can ride can depend on class behavior and local rules. The class system overview is a good starting point. PeopleForBikes

Some public lands use class definitions in access decisions (example from NPS). NPS example

FAQ

Is a Bafang mid‑drive hard to install?

Harder than a hub kit, but manageable with the right tools (crank puller + BB tool) and careful torque.

Do I need to upgrade my brakes?

If your current brakes feel “just okay,” yes. E‑bikes are heavier and faster.

Related guides (same hub)

Official resources (worth bookmarking)

Similar Posts