Help! ideal gearing

[downy8]

Gearing help

HI all this is my first post and am looking for some help regarding the gearing on my bike.... I have just purchased a BBS01B 250W midrive motor which I am going to fit it to my Cannondale F29 lefty and I was wondering about the gearing. It has a BB30 BB which I have bought the adaptor for but it is currently a using a 38/24 front ring and and a 11-36, 10-speed cassette. As the BBS01B chain ring seems to be 46T I was wondering what issues might arise, I would like top speed as well as some hill climbing ability although my 20 mile return commute doesn't have more than a couple of long slight inclines.... Can I keep my front dr or does that have to go, and if so should I change to a smaller front ring ie Lekkie and a wider range rear cassette like the Sunrace CMS3? also is a 10 speed cassette ideal? and if not what would you suggest? Many thanks Robert....

 

[peter.c]

You should be ok with the 46t the front with 10 speed rear will give a good spread
A 42t lekkie is the smallest before problems with the chain line
Dr has to go
You might consider the programme lead to adjust the settings

 

[vfr400]

You need higher gearing when you convert a bike to electric. Your gearing with the 46T ring will be fine.

 

[downy8]

Thanks for the replies... I have already ordered the programming cable btw and some hydraulic brake sensors....

What worries me is if I am on my 38t front ring I can’t pull away on a humpback bridge if in the lowest gear on the cassette.....I always have to Change down to the 24t front ring to find low enough gears and I am worried about over working the motor.....
Thanks Vfr400 I ordered the battery I saw you recommended another member which was the Yose 36v 16ah......

Thanks again Rob.......

 

[anotherkiwi]

Gearing help

HI all this is my first post and am looking for some help regarding the gearing on my bike.... I have just purchased a BBS01B 250W midrive motor which I am going to fit it to my Cannondale F29 lefty and I was wondering about the gearing. It has a BB30 BB which I have bought the adaptor for but it is currently a using a 38/24 front ring and and a 11-36, 10-speed cassette. As the BBS01B chain ring seems to be 46T I was wondering what issues might arise, I would like top speed as well as some hill climbing ability although my 20 mile return commute doesn't have more than a couple of long slight inclines.... Can I keep my front dr or does that have to go, and if so should I change to a smaller front ring ie Lekkie and a wider range rear cassette like the Sunrace CMS3? also is a 10 speed cassette ideal? and if not what would you suggest? Many thanks Robert....

With over 4,000 km on my GSM (BBS01 clone) on hilly Basque Country roads here are my thoughts:

To keep the chain line you could first of all try the sunrace 11-46 cassette with the stock 46 tooth chainwheel, most people change the stock chainring for a lighter one, my double weighs about the same as the stock single chainring...

On my first try at something over >17% (well over...) I stalled the motor running 46:32. I swapped for a double using a precialps spider. I was a little too pessimist with the 42 I mounted, a 44 would have been a better fit and the granny is a 32 which will climb most anything. I have a 7 speed 11-32 cassette.

If I was going to start over today with my gearing I would go back to a single 38 tooth on the front and upgrade to 9 speed and a sunrace 11-40 cassette. This bike is for moving me and stuff (in a trailer) around so high top speed is not on the program. And the Basque hills have not been flattened...