Installation Problems With My New Kit

[kernow60]

Hi, some help and advice required please.

O.K. onward from my previous thread, my kit has arrived (Bafang 8-Fun 250w mid-drive kit) and I'm currently in the midst of fitting it, assembled the chain-ring onto the motor installed the motor into the 68mm b/b shell, so far so good, then I noticed the edge of the 44t chain-ring is just coming into contact with the rear fork, the rear forks are quite wide presumably due to the rear tyre being quite wide on a very narrow rim (hydraulic disc brakes.)

So I tried placing a small s/s washer between the motor flange and the chain-ring which just gives it clearance but only just, still to close for my liking, so I removed them.
I then removed the motor from the b/b and fitted a large washer which is approx 1.5mm thick, now that along with the small recess in the motor to which the edge b/b shell sits against is now covered by the large washer and after re-assembly gives me approx 3.5mm clearance which looks much better.

Now my next problem is the chain line I have a 12-32t cassette and there is no-way the largest 32t and the next one to it are going to line up, so will I be able to use the bike if I only use six of the eight gears?, and will it climb o.k. or is it to going to put too much strain on the motor, or more to the point will it put to much strain on me, in other words will the motor still assist me o.k. in the higher gears.?

I can't see fitting a different chain-ring with a deeper offset is going to help because the governing factor is still the clearance between edge of chain-ring and the rear fork, unless I can fit a smaller chain-ring but I suppose that could mean the gearing may be to low, the rear forks do taper in toward the b/b at the point where the 44t chain-ring (supplied in the kit) is close to contacting the rear fork, so with a smaller chain-ring I could get it closer.
Is there any other solutions I haven't thought of.?

I read on here someone said it's not always straight forward fitting these kits and you may have to make things fit and work, well I can see why now. lol .............................

 

[trex]

chain line is always a problem with any bike with derailleur. Concentrate on solving small problems first and take the bike out for some test rides. You only need to mind the top and bottom gears and be kind to them for the moment. I thinnk you have plenty of torque with a 250W unit, unless you wigh more than 15st.
Fordulike is quite experienced with chain line, I am sure he'll come here later.

 

[kernow60]

Hi trex
Thanks for the reply, yes I will go with what you said and see how things are, although I'm a way off anywhere near trying it yet,still have all the other bits and pieces to fit as well as the battery.
I'm not unduly worried about only having the use of 6-gears I just don't want to stress anything by using a higher gear on the hills.
Thanks.
Oops almost forgot I'm around 12-stone.....ish.

 

[D8ve]

What about reversing the chain ring there is some offset in fitting.

 

[Fordulike]

Now my next problem is the chain line I have a 12-32t cassette and there is no-way the largest 32t and the next one to it are going to line up, so will I be able to use the bike if I only use six of the eight gears?, and will it climb o.k. or is it to going to put too much strain on the motor, or more to the point will it put to much strain on me, in other words will the motor still assist me o.k. in the higher gears.?

As trex mentions, I had a similar problem with chain alignment when I first fitted my BBS02.
My kit came with a 48T chainring, but luckily I didn't have any issues of clearance with the chainstay.

I did have major issues with the chain jumping off the chainring, when the bike was in either the first or second gear.
This was partly down to the fact that I stupidly removed the front derailleur cage, and also there was not enough offset from the original Bafang chainring.

The only satisfactory solution for me was to refit the front derailleur cage, and purchase a custom chainring. Now I have eight fully usable gears.

This is the one I bought:

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

There are others out there such as the Lekkie Bling Ring:

https://www.empoweredcycles.com/products/8fun-bafang-bbs02-lekkie-bling-ring-chain-ring-42-tooth

Both of these chainrings improve the offset by about 5mm, which is enough to allow the use of the first two gears. For me anyway!

The offset gives greater clearance with the chainstay. The smaller ring size improves the torque for hill climbing.

It's not a cheap option to fit a custom chainring, but can vastly improve the rideability of the bike.

 

[Kinninvie]

My 44T chainring just cleared the chainstay by 0.5mm so I bought a Lekkie Bling ring from Brighton cycles and as above it moved the chainline in by 5mm but more importantly the diameter is 9mm less than the 44T so it improved the chainstay clearance to 1mm.
My chainline is now straight with gear 4 out of 8 so is perfect.
The top speed of my BBS02 only dropped from 34Mph to 30 with this so still plenty fast enough.
Some threads on here sugest hitting the chainstay with a hammer to improve clearance but I think that may be asking for trouble
Here is the thread. http://www.pedelecs.co.uk/forum/threads/my-bbs01-conversion.20226/#post-253053

Have you actually tried riding the bike in the 2 gears? It may be that what looks like a problem may in fact be ok .

 

[kernow60]

What about reversing the chain ring there is some offset in fitting.

Thanks D8ve
But no that's not possible, in fact it would be taking it the other way, outward by miles, instead of inward, also I wouldn't get the plastic chain-ring guard on.

 

[kernow60]

As trex mentions, I had a similar problem with chain alignment when I first fitted my BBS02.
My kit came with a 48T chainring, but luckily I didn't have any issues of clearance with the chainstay.

I did have major issues with the chain jumping off the chainring, when the bike was in either the first or second gear.
This was partly down to the fact that I stupidly removed the front derailleur cage, and also there was not enough offset from the original Bafang chainring.

The only satisfactory solution for me was to refit the front derailleur cage, and purchase a custom chainring. Now I have eight fully usable gears.

This is the one I bought:

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

There are others out there such as the Lekkie Bling Ring:

https://www.empoweredcycles.com/products/8fun-bafang-bbs02-lekkie-bling-ring-chain-ring-42-tooth

Both of these chainrings improve the offset by about 5mm, which is enough to allow the use of the first two gears. For me anyway!

The offset gives greater clearance with the chainstay. The smaller ring size improves the torque for hill climbing.

It's not a cheap option to fit a custom chainring, but can vastly improve the rideability of the bike.

Yes unfortunately for me I have very little clearance between the chain-ring and the lower rear fork so if I'm lucky I may get to use 6-gears out of the eight which will be o.k. I'm just concerned it will put stress on the motor by not being able to use lower climbing gears, or is that not the case.???

 

[kernow60]

My 44T chainring just cleared the chainstay by 0.5mm so I bought a Lekkie Bling ring from Brighton cycles and as above it moved the chainline in by 5mm but more importantly the diameter is 9mm less than the 44T so it improved the chainstay clearance to 1mm.
My chainline is now straight with gear 4 out of 8 so is perfect.
The top speed of my BBS02 only dropped from 34Mph to 30 with this so still plenty fast enough.
Some threads on here sugest hitting the chainstay with a hammer to improve clearance but I think that may be asking for trouble
Here is the thread. http://www.pedelecs.co.uk/forum/threads/my-bbs01-conversion.20226/#post-253053

Have you actually tried riding the bike in the 2 gears? It may be that what looks like a problem may in fact be o.k.

I will give it a try to see what it's like, but I think if I go with a smaller chain-ring it will lower the gearing for the gears I can use and not put to much stress on the motor, but maybe it won't make any difference in which case I could leave as is and just use 6-gears, instead of 8 . My only real concern here is not to overheat the motor by climbing in to high a gear.???

 

[RobF]

Depending on the cassette, you could probably put the smallest cog on first - next to the spokes - then the rest of the cogs in order.

This would have the effect of moving all cogs over by one, enabling you to use a bigger one as your 'first' gear.

Bit of a lash-up, but plenty of mountain bikers do it to fit a bigger cog - a so-called extender ring.

You would, of course, lose your current highest gear.

 

[Fordulike]

I will give it a try to see what it's like, but I think if I go with a smaller chain-ring it will lower the gearing for the gears I can use and not put to much stress on the motor, but maybe it won't make any difference in which case I could leave as is and just use 6-gears, instead of 8 . My only real concern here is not to overheat the motor by climbing in to high a gear.???

You should be ok for the majority of regular hills. The only concern would be, is that the smallest gearing you could go down to is something like 44T-24T.

The Bafang loves to be kept spinning fast, not only to help stop the controller from overheating, but to prevent too much strain on the internals.

If you were to encounter a hill where the gearing is such that the Bafang is nearly stalling, then this could cause damage to the controller, internals or both.

If your regular route involves a nasty hill, ride out to it, turn the Bafang off and try and pedal up it under human power alone. Bum on seat, not standing on pedals. If you cannot reach the top using only leg power, then don't expect the Bafang to be happy powering you up the same slope.

 

[kernow60]

Depending on the cassette, you could probably put the smallest cog on first - next to the spokes - then the rest of the cogs in order.

This would have the effect of moving all cogs over by one, enabling you to use a bigger one as your 'first' gear.

Bit of a lash-up, but plenty of mountain bikers do it to fit a bigger cog - a so-called extender ring.

You would, of course, lose your current highest gear.

Depending on the cassette, you could probably put the smallest cog on first - next to the spokes - then the rest of the cogs in order.

This would have the effect of moving all cogs over by one, enabling you to use a bigger one as your 'first' gear.

Bit of a lash-up, but plenty of mountain bikers do it to fit a bigger cog - a so-called extender ring.

You would, of course, lose your current highest gear.

Yes that sounds feasible, or maybe make-up a cassette up to suit at a later date once I know what would be suitable. I always have the option of putting on a smaller chain-ring but again will wait to see how it performs as is at the moment, it may not be an issue.

 

[kernow60]

You should be ok for the majority of regular hills. The only concern would be, is that the smallest gearing you could go down to is something like 44T-24T.

The Bafang loves to be kept spinning fast, not only to help stop the controller from overheating, but to prevent too much strain on the internals.

If you were to encounter a hill where the gearing is such that the Bafang is nearly stalling, then this could cause damage to the controller, internals or both.

If your regular route involves a nasty hill, ride out to it, turn the Bafang off and try and pedal up it under human power alone. Bum on seat, not standing on pedals. If you cannot reach the top using only leg power, then don't expect the Bafang to be happy powering you up the same slope.

I think a 24T chain-ring would probably be perfect as far as fitting is concerned and would mean I could use more gears, simply because it could be moved in closer to the b/b due to it's much smaller diameter, but it would probably be somewhat too low, unless of course I were to put smaller gears on the cassette. My head is starting to hurt now with all these permutations.

 

[Fordulike]

I think a 24T chain-ring would probably be perfect as far as fitting is concerned and would mean I could use more gears, simply because it could be moved in closer to the b/b due to it's much smaller diameter, but it would probably be somewhat too low, unless of course I were to put smaller gears on the cassette. My head is starting to hurt now with all these permutations.

No sorry, I meant in your current situation you can only go down to 44T chainring and 24T rear sprocket for gearing purposes.
This wouldn't be ideal for really steep hills.

A custom 42T chainring may open up the possibility to use your largest sprocket size, which is 32T. Combined with the smaller chainring, this would keep the Bafang spinning faster on steep hills.

 

[kernow60]

No sorry, I meant in your current situation you can only go down to 44T chainring and 24T rear sprocket for gearing purposes.
This wouldn't be ideal for really steep hills.

A custom 42T chainring may open up the possibility to use your largest sprocket size, which is 32T. Combined with the smaller chainring, this would keep the Bafang spinning faster on steep hills.

Oop's silly me, I have seen MB's with really small chain-rings and thought that is what you meant. So is 42T the smallest option.?

 

[Kinninvie]

Yes
To go smaller than 42T requires a spider and that moves the chainring further away from the centre.

 

[kernow60]

Yes
To go smaller than 42T requires a spider and that moves the chainring further away from the centre.

O.K. I have tried the gears with the bike hanging from my garage ceiling and I have 6-gears out of the eight and I'm happy with that, a little adjustment is needed but they are all there. So once my rivnuts arrive next week I can secure the battery to the frame and give it a road test.
Will keep you posted after my first trial run.
If I feel I need to go smaller with a 42T chain-ring I still have the added option to change the rear cassette ratio's if need be.
Thanks again guys for the help & advice.

 

[kernow60]

O.K. tried her out today, for two reasons the first to see if I'm comfortable with the battery, zip-tied and taped to stop it moving, on the sloping top tube and it appears fine so will fix it permanently with rivnuts once they turn up.

Secondly, wanted to see how it performs and what the ratios are like with the only 6- available gears out of the 8, well I have to say really impressed with the Bafang 8-Fun motor, so smooth and quiet. With regards to the gearing using the 44t chain-wheel with the lowest possible gear I can use on my 8-speed cassette which is the 24t gives me 49.8 inches, sorry but I'm old school and inches it's the only thing I can relate too lol , whereas if I could have used the lowest (32t) it would go down to 37.5 inches so quite a loss really in terms of low down gearing for really steep hills which we have a lot of down here in Cornwall.

So what I propose is to obtain and fit a 42t chain-ring which coupled to the 24t gives me 47.6 inches, it's obviously better but doubt if it's going to be enough.? So is there a Bafang 42t chain-wheel available as a direct replacement or do I have to go with an expensive custom jobbie.!!!
By chance does anyone have one they want to get shot of.?

One other point I'm going to address is I am going to try and get the chain-wheel closer to the bottom fork, there is at present about a 3mm + gap between the edge of the chain-ring and the fork, which I feel can easily be reduced down, especially with a 42t chain-wheel the smaller diameter will allow me to get closer because the tubes are tapering back toward the b/b shell.
So I have ordered a few 32mm ~ 47mm x 0.5mm thick shim washers, 32mm being the bore size which will fit over the Bafang b/b shaft, these will replace the much thicker copper washer I have on at present and allow me to get much closer tolerances.

So in conclusion quite happy with everything in general, just need to sort a few issues and go out and have some fun.

 

[trex]

this one looks nice:

http://precialps.com/uk/chainring/9-plateau-decale-42-dents-anti-deraillement.html

 

[kernow60]

this one looks nice:

http://precialps.com/uk/chainring/9-plateau-decale-42-dents-anti-deraillement.html

Hi trex
Yes I totally agree, so are these type of "bling" rings, for the want of a better word, all that are available, only I was hoping to get hold of a Bafang 42t chain-ring, assuming there is such a thing, also it should be a much cheaper option.
Thanks..........