alltoo BBSHD 130BCD Spider and Chainring

Big rings on a BBSHD answer one complaint: spinning out. The motor has a crank-speed ceiling, and with the stock ring on a flat road that ceiling arrives before many riders want it to. A taller ring lets the same crank speed push the bike faster.

The arithmetic is plain. At 90 rpm on an 11T cog, with a wheel about 2.1 m around, each ring gives a fixed speed.

Real speed depends on pack voltage, wind, tyres and the rules where you ride. Those numbers tell you what the gear allows when rider and motor are both spinning comfortably.

Don't dismiss the colour on a build like this. A BBSHD conversion is usually someone's own project, and a red ring against a black motor housing is one of the few drive-side details you get to choose. alltoo describes the finish as smooth, bright and fade-resistant, so the colour should survive regular washing.

Treat 52T–60T as the core of the range. Those sizes appear everywhere alltoo describes the set, and they match what a 130BCD spider is for. The 39T, 46T and 58T mentions show up in one description but not the other, so confirm the exact size on the option you pick.

Where you ride, and on what pack, picks the core size for you.

• 52T: the gentlest step up from the stock 46T; still copes with short rollers on 48V.
• 54T: steady 52V cruising on bike paths and flat roads.
• 56T: long flat stretches with big wheels and an experienced rider.
• 60T: flat country only, where the motor spends its day at cruise.

The reason is heat. A tall ring on a hill forces the BBSHD to turn slowly under high current, and the controller and windings heat up fast. The nylon primary gear inside the drive also takes its heaviest load in that situation, a common wear point on tall-geared, heavy builds covered in the nylon gear guide.

Size also changes chain length. Moving from 46T to 60T adds about three to four inner-plus-outer link pairs.

Narrow-wide teeth alternate thick and thin to fill the gaps between the chain's inner and outer plates. That grip keeps the chain on without a front derailleur, which is the whole reason 1x drivetrains work. It also means the ring needs an even tooth count, which every size here has.

Chain drops on a big ring usually trace back to one of a handful of causes.

1. Poor chainline: the chain runs at a sharp angle in the largest or smallest cog.
2. Worn chain: a stretched chain rides up the teeth; check it with a chain gauge.
3. No clutch derailleur: chain slap over bumps lifts the chain off.
4. Shifting under full power: a gear sensor that cuts the motor during shifts helps.

Cleaning is simple. Degrease the ring with the chain, rinse, dry and lube only the chain. Avoid harsh acid cleaners on anodised parts, which can dull the colour over time.

Replace chain and ring together when the teeth start to look hooked or shark-finned. A new chain on a worn ring skips under the BBSHD's torque, and a worn chain eats a new ring quickly. Aluminium rings on a mid-drive are wear parts; plan for them.

The set fits the BBSHD, not the BBS01 or BBS02, whose output spline is a different size. Confirm the configuration includes the spider as well as the ring, since the set is designed as a matched pair. Then follow the usual spider routine with the right tools.

1. Remove the drive-side crank arm with a matching crank puller.
2. Unbolt and remove the stock ring from the splined output.
3. Fit the spider with medium-strength threadlocker on its bolts.
4. Bolt the ring to the spider in a star pattern with a torque wrench.
5. Lengthen the chain, refit the crank and check chainline against the middle cog.

Give the new ring a short shakedown ride before trusting it on a long commute. Recheck the spider and ring bolts once the bike has a few climbs on it, because fresh threadlocker and new mating faces can settle slightly under the motor's torque. A quick pass with the torque wrench costs two minutes.

For the crank and lockring side of the job, follow the BBSHD install guide. If the chain rubs the ring in the biggest cog, the chainline is off, and a thin spacer behind the spider or a different offset ring is the fix.

• For a harder spider: the IQ Labs stainless 130BCD spider plus a ring of your choice.
• For the same idea in black 7075: the FREERDNG 50T–60T set.
• For hills: a direct-mount ring from the BBSHD chainring guide.