A narrow-wide chainring for BBSHD, BBS03 and M625 motors that uses the standard 104mm four-bolt pattern. It bolts onto a 104BCD spider rather than straight onto the motor, which gives small, climbing-friendly sizes down to 32 teeth.
The BBSHD does not take ordinary bicycle chainrings straight onto its drive. Its own rings, like the CHAOZHU and Powallon, are made to bolt onto the motor directly. A spider changes that: it bolts to the motor and presents a standard bolt pattern, and this ring uses the common 104mm, four-bolt pattern that mountain bikes have used for decades.
This part is the ring half of that system. It is a narrow-wide chainring in 32, 34 or 36 teeth with a 104BCD mount, made for BBSHD, M625 and BBS03 motors fitted with a standard Bafang-fit 104BCD spider. It is not a spider itself, so the bike needs one already or needs one alongside it.
A spider also sets the chainline. The ring's position relative to the frame is fixed by the spider's shape, so the spider you choose decides whether the chain runs straight. The BBSHD chainring guide compares spiders and one-piece rings on chainline.
| Spec | Value |
|---|---|
| Brand | Generic |
| Model | CDBBRRBOA-7435A412 |
| Ring type | Narrow-wide single chainring |
| Tooth counts | 32T, 34T, 36T |
| Bolt circle diameter | 104mm (104BCD) |
| Bolt count | 4, per the 104BCD standard |
| Smallest size on 104BCD | 32T, the pattern's practical minimum |
| Mounting | Standard Bafang-fit 104BCD spiders |
| Motor fit | Bafang BBSHD, M625, BBS03 1000W |
| Chain retention | Narrow-wide teeth match inner and outer chain plates |
| Front derailleur | Not needed; built for single-ring setups |
| Included | 1 chainring |
The sizes on offer are all small by BBSHD standards. Most kits ship with a 44T or 46T ring for road speed, and on steep trails that leaves the motor turning slowly under heavy load. A slow-turning BBSHD under heavy load runs hot and delivers less of its power, which shows up as fading assist near the top of long climbs.
A 32–36T ring gears the whole bike down, so the motor spins faster on any climb. Compared with a stock 46T ring, the reduction is large:
| Ring | Ratio on 11T cog | Ratio on 42T cog | Change vs 46T |
|---|---|---|---|
| 36T | 3.27 | 0.86 | 22% lower |
| 34T | 3.09 | 0.81 | 26% lower |
| 32T | 2.91 | 0.76 | 30% lower |
Those percentages apply to every gear on the cassette. The low end becomes a crawling gear for loose, rocky climbs and loaded fat bikes. The top end drops too, so fast road stretches spin out sooner.
Tooth count also changes how the throttle feels. With a small ring, a thumb of throttle from a standstill pulls the bike up to speed in the low cogs with less strain, which helps on loose starts where a big ring would spin the rear tire or stall the motor under load.
Smaller rings help the motor as much as the rider. Keeping the BBSHD spinning up in its efficient range on long climbs is one of the simplest ways to cut heat soak, alongside sensible current settings. Motor speed, torque and heat are tied together in the BBSHD 1000W guide.
Fitting the ring is quick once the spider is on the motor. If the spider is new too, the job becomes two stages: spider to motor, then ring to spider. Both need the drive-side crank arm off first, so plan to do them together.
Chain length changes with ring size. Going from a 46T ring down to 32T frees a lot of chain, so remove links until the rear derailleur has proper tension in the smallest cog without over-stretching in the largest.
A spider adds one more set of bolts to the drivetrain, and those bolts see motor torque on every pedal stroke. A quick check with a hex key every few weeks catches a loosening bolt before it becomes a creak, then a wobble.
Keep the spider's instructions to hand for its own bolts and spacers, since spiders differ. Motor mounting and crank removal are covered step by step in the BBSHD install guide.
There are two ways to change a BBSHD's gearing. One is a one-piece ring that bolts straight to the motor, like the CHAOZHU or the Generic steel sprocket. The other is a spider plus a standard ring like this one. Each suits a different kind of rider.
Pick this ring if you already run a 104BCD spider, or if you expect to experiment with gearing and want each change to cost only a ring. Pick a one-piece ring if you want a single part with a known offset and no extra bolts to check. For a 130BCD setup, which suits large road-speed rings rather than small climbing ones, the IQ Labs 130BCD spider is the relevant part instead.
Four questions settle whether this ring fits: you have, or will buy, a 104BCD spider made for the BBSHD; your motor is a BBSHD, BBS03 or M625; you want 32, 34 or 36 teeth; and your drivetrain runs a single ring with no front derailleur.
A small ring with a dirty chain wears faster than a large one, because fewer teeth share the load. Clean and lube often, and replace the chain before it stretches.
It is a narrow-wide chainring with a 104BCD bolt pattern. It mounts onto a standard Bafang-fit 104BCD spider, which the motor needs separately.
The 104mm bolt circle leaves no room for fewer teeth; 32T is the practical minimum for any 104BCD ring.
No. Without a 104BCD spider, there is nothing for the four bolts to attach to on the BBSHD's drive.
The maker lists the BBSHD, M625 and BBS03. BBS02 riders should check their spider and ring fit separately.