Smaller chainrings for BBS-02?

John L.

Member
I'm impatiently waiting for Surly to deliver my Ogre so I can complete my BBS-02 build. I ordered the 44-tooth chainring available from EM3EV (the smallest they sell) because I have a lot of steep hills in my area. I noticed Court's recent review of the BME Shadow, in which he says:
the other BMEBIKES models come with an aftermarket Raceface NW sprocket in the front that’s a smaller diameter with fewer teeth.
A quick check of BME's website shows that BME's other bikes use smaller front chainrings with cassettes in the rear. I've read that anything smaller than, say, a 42-tooth chainring on a BBS-02 creates chainline issues because the stock Bafang chainrings have an offset profile. A standard chainring would lack this offset profile. In short, my question is whether any special adaptation is needed to adjust the chainline when using a smaller chainring on the BBS-02?
 

Hong

Active Member
We use an adapter for run any 104 bcd 4-bolt ring on the Bafang BBS motors. The bike currently has a 44t ring on it, but you can probably go down to 38t with no clearance issues. The adapter does push the chainline out a bit, but this can be compensated in the rear depending on the hub you're using.
 

Gus

Active Member
I'm impatiently waiting for Surly to deliver my Ogre so I can complete my BBS-02 build. I ordered the 44-tooth chainring available from EM3EV (the smallest they sell) because I have a lot of steep hills in my area. I noticed Court's recent review of the BME Shadow, in which he says:


A quick check of BME's website shows that BME's other bikes use smaller front chainrings with cassettes in the rear. I've read that anything smaller than, say, a 42-tooth chainring on a BBS-02 creates chainline issues because the stock Bafang chainrings have an offset profile. A standard chainring would lack this offset profile. In short, my question is whether any special adaptation is needed to adjust the chainline when using a smaller chainring on the BBS-02?
You may be surprised what the BBS02 can do even with a 44T. What rear cassette are you running? Did you get the 750W?

I run an 11-34 cassette with a 48T and there hasn't been a hill I could not climb loaded to the gills with panniers front and rear.

However, HPC and California eBikes both sell adapters that can do down to a 36-38T. I've read people having issues with these things though if you change more than 1 gear at a time.
http://www.hi-powercycles.com
http://california-ebike.com/product/ba130-bafang-chainring-adapter/
 

John L.

Member
Gus, I'm going to try the 44-tooth Bafang chainring with the stock 11-36 cassette for a while and see how that works for me. I've got steep hills around my house, creaky knees, and I'd like to pull a small cargo trailer from time to time. We'll see how it goes. I'm researching the viability of a smaller chainring for future reference just in case. Meanwhile, still waiting on Surly's shipment.... ETA: 2 weeks (I hope).
 

Mike leroy

Active Member
Gus, I'm going to try the 44-tooth Bafang chainring with the stock 11-36 cassette for a while and see how that works for me. I've got steep hills around my house, creaky knees, and I'd like to pull a small cargo trailer from time to time. We'll see how it goes. I'm researching the viability of a smaller chainring for future reference just in case. Meanwhile, still waiting on Surly's shipment.... ETA: 2 weeks (I hope).
Which crankset are you going with? I am considering SRAM X01.

  • 11-speeds (10-12-14-16-18-21-24-28-32-36-42)
  • Available in 26-, 28-, 30-, 32-, 34-, 36-, 38-, or 40-tooth
 

Gus

Active Member
Which crankset are you going with? I am considering SRAM X01.

  • 11-speeds (10-12-14-16-18-21-24-28-32-36-42)
  • Available in 26-, 28-, 30-, 32-, 34-, 36-, 38-, or 40-tooth
I would not recommend a large number of gears in the cassette because you will have to use a thinner chain. The chain is prone to breaking, especially with the 750w version.
 

Mike leroy

Active Member
I would not recommend a large number of gears in the cassette because you will have to use a thinner chain. The chain is prone to breaking, especially with the 750w version.
Would you recommend any SRAM crankset or a crankset of another brand?
 
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Mike leroy

Active Member
I would not recommend a large number of gears in the cassette because you will have to use a thinner chain. The chain is prone to breaking, especially with the 750w version.
Gus,

I want to make a detailed comparison between the Yamaha and BBS02 motor, controller and battery.

I have outlined what I consider to be the major comparison points.

Since you have a great deal of experience with BBS02, would you please critique the comparison points I have overlooked?

I listed the comparison features in this publically shared Google doc for anyone to use.

(Link Removed - No Longer Exists)

Thank you,

Mike