Bafang BBS02 chain line

[Fordulike]

This has probably been covered already and I'm sure I have read something somewhere before, but I can't seem to find any threads on it.

Fitted a Bafang BBS02 kit to an 8 speed cassette mountain bike today. It wasn't all plain sailing though, but I'll highlight that in another thread, when my mojo has returned lol.

Anyway, the kit is great, but I just could not get it it work with the two highest gears. The chain line throws the chain off when using those two cogs. At first I kept the front derailleur to see if it would keep it on, but that was a no go, so I ended up taking it off completely.

I've combated the issue by adjusting the rear derailleur screw, so that the derailleur can't move across to first and second. But being a perfectionist, I'd like to have the full range of gears working.

Any ideas?

 

[Topdonkey]

Mines the same, if I shift to first or second the chain comes off the front chainring so I've done the same as you and stopped the deralieur moving to first and second.

 

[ps4customgamer]

Are we just talking about front dérailleur tuning?
If so then is the front dérailleur correct for the gearing? I don't know the size of the chainrings so I can't even say what the correct one would be.

If your talking about the rear mech not working with the new crank then that could be down to rear dérailleur adjustment, your new hub motor/crank not being pushed all the way toward the frame or your rear dérailleur being totally bent out of shape and not being able to tell.

 

[Fordulike]

Are we just talking about front dérailleur tuning?
If so then is the front dérailleur correct for the gearing? I don't know the size of the chainrings so I can't even say what the correct one would be.

If your talking about the rear mech not working with the new crank then that could be down to rear dérailleur adjustment, your new hub motor/crank not being pushed all the way toward the frame or your rear dérailleur being totally bent out of shape and not being able to tell.

The Bafang chain ring is 48t, which is exactly the same as the largest front derailleur ring that I took off. I do think that it is an offset thing though.

 

[Fordulike]

Mines the same, if I shift to first or second the chain comes off the front chainring so I've done the same as you and stopped the deralieur moving to first and second.

That's good to know, in a bizarre good way. I think a chain ring with a bit more offset would sort the problem. Have you come across anything in this forum or Endless Sphere, on whether different offset chain rings are available?

 

[Fordulike]

Think I may have found the answer. Thank you Google

http://endless-sphere.com/forums/viewtopic.php?f=31&t=65946

 

[mfj197]

I'm surprised you couldn't get it to work by adjusting the front derailleur to work as a chain keeper. Chain line is a known issue but I've had no issues with my BBS01 yet, with no chain keeper. I think the chain line is a bit worse (i.e. further out) with the BBS02 as it's a little wider. There is a guy on Endless Sphere selling chainrings for these motors with projecting rims on both the inside and outside to keep the chain on. Not cheap, mind.

Michael

 

[Fordulike]

I'm surprised you couldn't get it to work by adjusting the front derailleur to work as a chain keeper. Chain line is a known issue but I've had no issues with my BBS01 yet, with no chain keeper. I think the chain line is a bit worse (i.e. further out) with the BBS02 as it's a little wider. There is a guy on Endless Sphere selling chainrings for these motors with projecting rims on both the inside and outside to keep the chain on. Not cheap, mind.

Michael

The chain would rub on the front derailleur and I spent a few hours trying to make it work. The link I posted above is a custom made one too, although it doesn't have the rims like you mention. I might have another dig about on ES.

Some people are obviously having chain line issues, otherwise they wouldn't be bringing out these custom mods.
A few more quid won't hurt... Unless the missus finds out

 

[Nealh]

I currently have my BBS01 on my Norco hybrid and have no issues with the chain line but will see what happens when I move the kit over to my Cube AMS, It does have a 73mm BB so the extra few mill may make a difference optionally I may grind 2.5 mm or so off the BB if I have to. That Lekkie ring looks the bis but $100, is a lot for one ring.

 

[Kinninvie]

I have had my bbs on a 6 speed bike with a 68mm BB and its now on an 8 speed bike with a 73mm BB and the chain works on all gears and has never come off even though I do a lot of offroading on the moors and through forests including lots of roots and small jumps.
Guess its the luck of the draw.
I use standard front chainrings in 44T and 48T sizes.
Below is an example of my riding

 

[mechaniker]

the chainline issue with bbs01 was a problem on my bike too so I bought this 42th chainring and it makes a much better chainline as the original Bafang now I can use all gears and no problems anymore, it is good but not cheap:
http://www.alcedoitalia.it/shop/accessori-bbs/corona-42-denti-per-bafang-centrale-bbs01/
one other chainring I found was that one it´s a bit cheaper:
http://www.edibike.it/prodotto/corona-singola-42-denti-per-suzhou-bafang-8-fun-centrale-bbs-01-02/
If you have a trike with a longer chainline you can think about this one, a double chainring 42/48 front:
http://www.edibike.it/prodotto/corona-doppia-4248-denti-per-suzhou-bafang-8-fun-centrale-bbs/

if you search the net you can find a lot of choise´s for the bbs-motor and with them it´s possible to find a solution for any problem

on my "Bigfoot" fatbike outfitted with bbs01 I use a 32/38 double chainring thanks to the long distance between bottom-bracket and rear-hub

 

[Fordulike]

Big thank you to everyone who has provided answers in this thread.... BUT...

To my pleasant surprise, after taking it out for a decent run this afternoon, I've come to the conclusion that even if I could use first and second gear, I wouldn't use them anyway.
For most of the time I was pottering around using PAS level 1 and 2. With PAS 1 and third gear, it pulls smoothly off the line.

It took half an hour to get used to riding a bike properly again. My previous bike was a throttle only hub motor and the style of riding is obviously quite different.

But do you know what, the Bafang just felt so good to ride. I haven't even bothered putting the throttle on coz the PAS is so good.

Anyway, back to the gear thing. When it came to a big hill, I kept it in third and flew up using PAS 5. It's powerful, maybe a bit too powerful, as I didn't need to use an assistance level past 5.

It whirrs quietly away in the background and just gets on with the job it was designed to do. Well done Bafang

 

[Topdonkey]

I use mine the opposite to you, I have the throttle fitted on mine and rarely use the pas, I find the pas a bit too coarse like its all or nothing and i'm constantly moving up and down the power levels, however, if i just use the throttle, then i find it very linear and smooth and i just peddle and push the throttle as much as i want to give me the required boost

 

[Fordulike]

I use mine the opposite to you, I have the throttle fitted on mine and rarely use the pas, I find the pas a bit too coarse like its all or nothing and i'm constantly moving up and down the power levels, however, if i just use the throttle, then i find it very linear and smooth and i just peddle and push the throttle as much as i want to give me the required boost

I wonder if your PAS levels have been programmed slightly different to mine. I did e-mail Eclipse to ask how the latest batch are programmed, but have yet to receive a reply...... again

 

[Topdonkey]

Eclipse forgot to programme mine before sending it out, so its the bog standard bafang programming that gives about 50% assist on the pedals in 9 levels, or full power on the throttle in any level

 

[Kinninvie]

I use mine in the bottom 2 gears quite a lot (34 and 30T) as I have steep hills around here and also for technical twisty stuff in the forests or when mudplugging through the peat bogs.
The gear I use least is top (11T) as it gets me to 34Mph but will only maintain it on the flat and not even then if there is a headwind.
I would love a cassette with a 38T gear and a 12T top gear but have not found anything yet.
Like you I find myself pedalling almost all the time with this whereas on my hub motored bike it tends to get ridden mostly on the throttle.

 

[Fordulike]

Having worked with the Bafang kit for the last couple of days, I have noticed the reasons behind the poor chain line.
You don't really spend a thought on bike geometry, until you start fitting motors.

Bafang have played it safe with the offset on the 48T, otherwise the teeth have a strong possibility of touching the chainstay.
This has led to problems with some bike's chain line, where the front chainring offset is just not great enough for 1 or 2 of the lower gears to be used.

Bafang are quite elusive when trying to find out specific detail about their products, so I wonder if anyone can help answer this:

With the stock Bafang chain rings, which I believe range from 44T - 52T, are the offsets all the same, or do they get bigger as the number of teeth get less?

I reckon an extra offset of only 3mm would cure the problem, but with a 48T, might cause an issue with the chainstay.

I'll throw that one over on the ES forum too. The more the merrier

 

[trex]

the bigger the chain ring, the bigger the problem keeping a perfect chain line.
With the 750W, I think Bafang made an error fitting 48T, should have fitted the smaller 44T.
The motor running too fast for me anyway.

 

[Fordulike]

the bigger the chain ring, the bigger the problem keeping a perfect chain line.
With the 750W, I think Bafang made an error fitting 48T, should have fitted the smaller 44T.
The motor running too fast for me anyway.

Ultra quick reply... wow... why aren't you out riding lol

So, do you reckon if I fitted the 44T, it may cure my problem?
I can pick up a stock Bafang 44T from Em3ev for peanuts.
Plus I like the fact they are made out of steel, not aluminium like the Lekkie Bling Ring. Who cares about saving weight lol

I get what you mean by running fast, it's so powerful

 

[trex]

I went out this morning for a short ride after breakfast, it was a bit too cold for my liking, came back for coffee and donut.