Which chainring?

[Farther]

I'm looking for advice on selecting the correct chainring for my ebike build.

The base bike will be a Specialized Roll Sport comfort bike. I'm 64 and ride mostly on paved bike trails and secondary streets. Lots of moderate hills around my home. Not a commuter. I also will not be installing the throttle. I want to pedal and want some assistance from the motor, not an electric motorcycle. Battery I'm leaning towards is a dolphin 48v.

Buying a BBS02 kit from Luna and I have a few options regarding the chainring. They are 46/48/52 tooth. Any thoughts and advice would be much appreciated.
I have other questions, but will post those separately.

 

[WilliamT]

Your current bike uses a 48/38/28 chain ring. You can go with a 46 or 48. The 52 will be too big and probably require you to get a longer chain. If you ride mainly with the 48 right now (your current largest front chain ring) then stick with the 48, otherwise get the 46. Its not ideal, but will be slightly easier to pedal.

 

[ricardoafm]

I am planning to buy an ebike conversion kit.

It will be installed on a Trek Shift 2, with 26" tires.

Which chainring size would you recommend me?

It came with 48/38/28 chainrings and has a 7 speed rear cog (14-34).


I plan to use this bike for grocery shopping in my neighborhood and riding to work and school.


Do you think I should go for the 500W motor? or 750W?



best,

Ricardo

 

[harryS]

I bought the 750W Luna BBS02 back in 2016. I chose the 48T because I had an inexpensive Diamondback bike, and the smallest gear on the rear was 14T. Mine was set up by Luna to allow throttle in PAS0, and throttle could be feathered in on any higher level. Ive heard that perfect balance was changed and on new kits, you either use throttle or you use assist. I'm in a pretty flat area, but I know how to shift gears, so I've never lugged the motor. On 48V, throttle only, top is around 26 mph. Not much faster on 52V. Maybe 27 mph. Luna batteries too.

You don't do yourself any favors not installing the throttle unless there are laws against it, and have overzealous enforcement. Last time I rode. I had it in zero assist and feathered in the throttle as needed.

Might as well get the 750W motor, unless there is a big price delta. Mine was probably a 500W unit with a sticker added.

I've had to pedal the bike on a 30 mile group ride when the socket in the battery came loose. Wish I had figured it out on the ride, but at least I figured it out when I got home. Aside from that mishap, about a week after I got it running. the BBS02 has been dependable. I would like a better display like the color models, but why fix what isn't broken.

 

[TOOSLOW]

I am not sure why you would limit your self to one chainring? I have 5 in my arsenal, they are so easy to change by the way, and to service a chain, removal is best for cleaning and to lube the chain as well, so killing two birds with one stone, simple. My range is from a 14 tooth up to a 22. This is the largest and smallest available on my cx Bosch. I actually have given the thought of having a custom 25 tooth made, just for the times you want that extra speed! And considering that a chain ring can had for under $10, why not two, maybe three?

 

[harryS]

The crank axle for for the Bafang BBS02 sticks out a bit, so it needs special chain rings that bring the sprocket back closer to the frame. So that us limits users to what Bafang makes and one small time supplier (Lekkie).

 

[TOOSLOW]

The crank axle for for the Bafang BBS02 sticks out a bit, so it needs special chain rings that bring the sprocket back closer to the frame. So that us limits users to what Bafang makes and one small time supplier (Lekkie).

Ah, captive market. I possible option again would be custom sprockets made to order.

Nitro Chain - Custom Manufactured Sprockets & Hubs

www.rollerchain4less.com