BBS02 chainring size what do you use?

[mt247]

I have 29er bike and I'm thinking what size chainring should I get with 750W 48V BBS02? Is 48t too much?

What sizes you're using and how's your experiences with it?

 

[Fordulike]

Mmmmm, I would say that a 48T might stress the Bafang's internal gears a little too much. Plus, it may stifle the very steep hill climbing ability.

I have the same BBS02 set-up as you, but with a 26er. I use a 42T Lekkie Bling Ring and it compliments my gearing very nicely, plus it improves the chainline.

Not many slopes I can't climb!

 

[mt247]

Mmmmm, I would say that a 48T might stress the Bafang's internal gears a little too much. Plus, it may stifle the very steep hill climbing ability.

I have the same BBS02 set-up as you, but with a 26er. I use a 42T Lekkie Bling Ring and it compliments my gearing very nicely, plus it improves the chainline.

Not many slopes I can't climb!

We don't have really steep hills here though.

 

[Fordulike]

We don't have really steep hills here though.

Urrrrm, faster acceleration

 

[mt247]

Urrrrm, faster acceleration

What is your top speed with 42t?

 

[Fordulike]

What is your top speed with 42t?

Fresh 48v battery and the 12T rear cog is about 28mph. But that's on a dead flat surface.
Realistically, I think that riding around on the 12T is not good for the drivetrain, so I tend to use the next one up.

 

[mt247]

Fresh 48v battery and the 12T rear cog is about 28mph. But that's on a dead flat surface.
Realistically, I think that riding around on the 12T is not good for the drivetrain, so I tend to use the next one up.

The reason why I was thinking about getting 48t so I could use more the mid range gears on my 11-36 10speed cassette.

 

[jarob10]

For road use, I’m using 52t with 11-28 on the back

 

[mt247]

For road use, I’m using 52t with 11-28 on the back

That's a big one. Doesn't overheat the motor? Is the acceleration slow?

 

[jarob10]

That's a big one. Doesn't overheat the motor? Is the acceleration slow?

never had a problem with overheat, although I do run an external controller. Acceleration is fine, and will pull my 85kg away from stationery no problem. 28t is reserved for when the battery is flat.

my usage case is road only, with clip pedals so please bear that in mind

 

[Nicholas Hammond]

I have been running with a Precialps (like lekkie) 42t chainring with an 11-36t cassette on my Boardman hybrid with BBS02 750w. I live in the Brecon Beacons in Wales and we have many 20%+ climbs locally. I am 74 with a heart problem so my motor has to work quite hard to get me up these climbs. I have found however that I’m spinning out on the flat or downhill and so I was looking at going to a 48t chainwheel however I saw a nearly new 52t at a bargain price and couldn’t resist it. I have been using this for a couple of months and it has been fine but at the top of some of these hills the motor has been hotter than I am comfortable with perhaps 40 degrees C. Like MT247 one reason I wanted to try a larger chainring was to better utilise the sprockets in the centre of the cassette with the best chain line for more of the time and this is perfect in that respect.
My next step is to try a cassette with a 46t bottom gear this will put my ratio back slightly to lower than the 42 chainwheel to 36 combination where the motor only ever got mildly warm.

 

[Peter.Bridge]

I went for 48t on a 29er with 11-36 rear cassette. Seems fine for steep off road tracks, not had to use the 36 rear cog yet, nor full power going up hills. Do sometimes get a bit of a clank when I use the 11t rear cog, I would rather use next one down I think. So far most of my riding is 10-30 % power , occasionally go up to 50% on steep hills. Trying to ride with a degree of mechanical sympathy! Did try full power and the 11t on the flat on a deserted straight road and got up to 31 mph (pedal assist) but that's too fast for me for everyday riding.