Worried about chain line on BBS01 fitted to Moulton APB with a Sturmey-Archer 8-speed hub

[Brian Liddell]

I’ve just bought a BBS01B to fit on my Moulton APB, a 20 inch wheeled bike, currently fitted with a Sturmey-Archer 8 speed hub gear.

The lowest gear on the Sturmey is direct drive, its sprocket is the biggest available 25 tooth, and so I’m planning to fit a 32 tooth chain ring using a 104 bcd adaptor on the BBS unit.

When this is done, the chain line will be well out of alignment. I’m thinking that this might not matter too much, as the chain will be continuously on the same chainring and sprocket.

Has anyone got experience of this set up? How much misalignment of the chain line is acceptable?

Thanks!

 

[vfr400]

I can't understand what you're saying. If you had a bike with 26" wheels and the gearing was about right for normal pedalling, then a BBS01 with a 44T chainring gives approximately the correct gearing, but if you have 20" wheels, the gearing is a long way too low. You're talking about a 32T chainring, which is substantially lower!

 

[Brian Liddell]

I can't understand what you're saying. If you had a bike with 26" wheels and the gearing was about right for normal pedalling, then a BBS01 with a 44T chainring gives approximately the correct gearing, but if you have 20" wheels, the gearing is a long way too low. You're talking about a 32T chainring, which is substantially lower!

Actually I inherited the Moulton with this setup, and yes the gearing is a bit low. But I’m old, and I live in a very hilly area (the English Lake District), and I’ve been reasonably happy with it. I’ve discovered that there's a Lekkie chain ring setup for the BBS01 that has an offset 40 tooth chainring that gives a much better chain line. But I’m concerned that this will be too high for me, especially if I run out of battery around here. So I hope to be able to fit something lower than 40 tooth, and I’m concerned about the chain line. I hope that makes sense, and thanks for your reply!

 

[vfr400]

Chainline isn't that important. It's just a case of whether the chain keeps coming off the chainwheel, which you can probably solve with a chain-guide.

 

[peter.c]

Any chain ring on a bafang less than 42 t has no dish at all, the 36 lekkie is flat

 

[Brian Liddell]

Any chain ring on a bafang less than 42 t has no dish at all, the 36 lekkie is flat

Lekkie seems to have a new 40 tooth chain ring setup that incorporates a replacement motor drive cover:
Lekkie Bling Ring 40T BBS package
However, I’m going to take vfr400's advice first, that "chain line isn't that important", provided the chain doesn't keep falling off!

 

[niggle]

Hi from a former Moulton APB S7 owner (with the truly terrible Sturmey Archer Sprinter 7 hub...)

With the motor installed you will not need anything like the low gears you have currently. Are you using 1/8" or 3/32" chain and sprocket? A 1/8" chain gives some leaway running on the chaingring which will be 3/32" or less, and if you use a 3/32" rear sprocket you get the same at the rear. OTOH don't use a bushed 1/8" chain unless the chainline is within 1mm, bushingless is better if not and a 3/32" bushless chain is basically a derailleur chain so can cope with snaking about a lot better (but obviously won't fit on a 1/8" rear sprocket ) The Sturmey 8 speed chainlines are here: http://www.sturmey-archer.com/files/catalog/files/35/SPECIFICATIONS - IGH S80 (W).pdf

One caveat: the Sturmey Archer 8 speeds don't have a great rep for reliability so putting extra power through one may not be so good for it, especially geared down quite low, which will increase the torque going through it. I would have suggested a front hub motor, if I had a clue about how the unique suspension fork would react to the torque, but I don't. Couid you fit a Shimano 8 speed hub if the Sturmey breaks? Gearing is higher but with a 24T sprocket dished outwards you will get a chance at a reasonable chainline I think. What is the chainline on the Bafang with standard and flat chainrings?

 

[vfr400]

People come on this forum wanting to convert all sorts of weird and wonderful bikes, but to be honest, in most cases, it doesn't make sense to convert them. Often, by converting them, you spoil everything that's good about them, and when you have an electric bike, many of the advantages that those bikes offer disappear. Unless you have a specific reason to convert that specific bike, I'd be looking for a different one to convert. All you need is a cheap catalogue bike with disc brakes and a diamond frame. Everything else can be changed or adjusted to suit any special requirements you have. You can pick up these bikes from second-hand shops, Facebook ads, Ebay, etc for less than £100.

 

[niggle]

People come on this forum wanting to convert all sorts of weird and wonderful bikes, but to be honest, in most cases, it doesn't make sense to convert them. Often, by converting them, you spoil everything that's good about them, and when you have an electric bike, many of the advantages that those bikes offer disappear. Unless you have a specific reason to convert that specific bike, I'd be looking for a different one to convert. All you need is a cheap catalogue bike with disc brakes and a diamond frame. Everything else can be changed or adjusted to suit any special requirements you have. You can pick up these bikes from second-hand shops, Facebook ads, Ebay, etc for less than £100.

Good points, the Mouton is a very special bike that rides far better than any catalogue bike, but knowing the bike also causes me to have some questions re the conversion, e.g. whether the motor fit the non standard frame's bottom bracket area, where is the battery going, is the frame separable (splits in half) and if so do you want to keep that ability, which would mean having to make some of the wiring easy to separate as well. Also what brakes do you have? Calipers are not really up to the job IMO, V-brakes OK but only if maintained well and the pads will wear out quickl in my experiencey, discs are not possible on any APB.

Example of an APB:



A hybrid with disc brakes would be an easier place to start.

 

[3wheeler]

Good points, the Mouton is a very special bike that rides far better than any catalogue bike, but knowing the bike also causes me to have some questions re the conversion, e.g. whether the motor fit the non standard frame's bottom bracket area, where is the battery going, is the frame separable (splits in half) and if so do you want to keep that ability, which would mean having to make some of the wiring easy to separate as well. Also what brakes do you have? Calipers are not really up to the job IMO, V-brakes OK but only if maintained well and the pads will wear out quickl in my experiencey, discs are not possible on any APB.

Example of an APB:

View attachment 32906

A hybrid with disc brakes would be an easier place to start.

 

[3wheeler]

I fitted BBSO1B to a Mouton, you need to turn the pivot bolt around and file head to 1/2 size. then you will need a shim between the motor and frame . After that you need to sort out chain line. I have also fitted Q100H to the front wheel which was a much nicer ride.

 

[niggle]

I fitted BBSO1B to a Mouton, you need to turn the pivot bolt around and file head to 1/2 size. then you will need a shim between the motor and frame . After that you need to sort out chain line. I have also fitted Q100H to the front wheel which was a much nicer ride.

Mouton blanc ou mouton noir?

 

[3wheeler]

Mouton APB5 , I live in Cornwall all hills, I am 75 whit Parkinson . I ride a 3 wheel 27 wheels whit a diff and a BBO750 mid drive.