Smallest possible chainring for bbs2

[stijn13]

What woude be the smallest possible chainring for bbs2?
Will this affect my top speed, or will the bbs2 just spin faster?
What is the max rpm for the bbs2

This is the smallest chainring that i found in previous triads. 38T
http://www.ebikeclub.it/shop/it/accessori/30-corona-38-denti-per-bafang-centrale-bbs01-e-bbs02.html

 

[mushymelon]

42 T is the smallest possible for a correct chain line. The 38t that you posted will bring your chain line out too far.
It will work with single speed or internal gear hubs though, and with an adapter you can go even smaller I ran a 34T with an adapter for a while but the chain line was not good.

The smaller the chainring the lower the top speed!

I'm currently running

-10spd zee Derailleur with a the Italian Alcedo 42t chain ring.

http://www.alcedoitalia.it/shop/accessori-bbs/corona-42-denti-per-bafang-centrale-bbs01/

Or this ones good too
http://em3ev.com/store/index.php?route=product/product&product_id=197

-Xt 10 spd shifter

- xt cassette 11 - 36
I have removed the 11t cog and added a 40T Absolute black extender cog with 13T adapter.
http://absoluteblack.cc/cassette-cog.html

IMO this is the best setup for the bbs02.

 

[stijn13]

42 T is the smallest possible for a correct chain line. The 38t that you posted will bring your chain line out too far.
It will work with single speed or internal gear hubs though, and with an adapter you can go even smaller I ran a 34T with an adapter for a while but the chain line was not good.

The smaller the chainring the lower the top speed!

I will use it on a kmx trike whit a nuvinci. So the chain line is no problem.
Where did you buy the 34t, what top speed can i expeckt?

 

[FastJohnny]

42 T is the smallest possible for a correct chain line. The 38t that you posted will bring your chain line out too far.
It will work with single speed or internal gear hubs though, and with an adapter you can go even smaller I ran a 34T with an adapter for a while but the chain line was not good.

The smaller the chainring the lower the top speed!

I will use it on a kmx trike whit a nuvinci. So the chain line is no problem.
Where did you buy the 34t, what top speed can i expeckt?

Glad to answer this as I was playing with gearing the past couple weeks and couldn't get a straight answer anywhere.

Running 34t x 12-36t on a 29er. Theoretical top speed is about 34mph, but the max the Bafang will let you do is 31.8mph (50kmh) and it will hit that under throttle.
I can still pedal it up to 20MPH or so. Tons of low end torque, and more than enough top speed pedaling, and a 31mph top speed is perfect for the singletracking I do.

Before I was running 42t alcedoitalia x 11x34, and then the 12-36. This would theoretically max out at 42.9mph, but again your limited to the 31.8mph speed limiter. In my lowest gear top speed under throttle was 16mph. It was also still geared way too high to pedal up hills with the assist turned off.

Ive determined that at full speed the crank spins the final gear at 143RPM or crank cadence. Hope this helps.

 

[slowhands]

Some people use the Lekke chainring, though it is not the smallest at 42T. It is offset in by 9mm, which corrects the chainline. it is said to prevent derailments, thanks to both the large offset and the narrow/wide teeth pattern.
http://electric-fatbike.com/bbs02-chainrings/