Alfine 11 speed Chainline

[Velonoir]

Hi All,
apologies in advance if this has been covered ad nauseam, this is my first post, and would appreciate comments from members.

I'm in the process of converting my ON ONE POMPETAMINE with rear facing dropouts and an Alfine 11 speed hub. I've fitted a Bafang BBS01, the standard chainring of which has a chainline of about 50mm. The Alfine has a chainline of 42.7mm so it's way out. It would seem that a good course of action would be to fit a 42T ( my original Alkine chainring was 39T, very hilly in the Peak District) Bling Ring which I understand has a few more mm of dish thus improving the chainline, but maybe not enough?

I'd be interested to hear if anyone else has had such a problem , and if anyone's fitted a reverse sprocket to an Alfine, I believe the Nexus sprocket is reversible with a dish to it and fits the Alfine?
Also would a chain tensioner of some sort be recommended, there's no facility for a derailleur fixing as the frame is designed for a single gear sprocket, so one would need to be fitted on the axle, which I don't really fancy as the wheel has to be tightened up really tight, don't really want to weaken the frame by drilling, but could probably cobble something together.

Any comments would be apreciated thank you

Pete

 

[KirstinS]

Hi All,
apologies in advance if this has been covered ad nauseam, this is my first post, and would appreciate comments from members.

I'm in the process of converting my ON ONE POMPETAMINE with rear facing dropouts and an Alfine 11 speed hub. I've fitted a Bafang BBS01, the standard chainring of which has a chainline of about 50mm. The Alfine has a chainline of 42.7mm so it's way out. It would seem that a good course of action would be to fit a 42T ( my original Alkine chainring was 39T, very hilly in the Peak District) Bling Ring which I understand has a few more mm of dish thus improving the chainline, but maybe not enough?

I'd be interested to hear if anyone else has had such a problem , and if anyone's fitted a reverse sprocket to an Alfine, I believe the Nexus sprocket is reversible with a dish to it and fits the Alfine?
Also would a chain tensioner of some sort be recommended, there's no facility for a derailleur fixing as the frame is designed for a single gear sprocket, so one would need to be fitted on the axle, which I don't really fancy as the wheel has to be tightened up really tight, don't really want to weaken the frame by drilling, but could probably cobble something together.

Any comments would be apreciated thank you

Pete

Hi Pete

I had a much loved pompetamine till I snapped the frame

Anyhow I have a alfine 8 bbs conversion. I have a bling rimg which really helps massively. An alfine chain tensioner also helps a bit more and finally a flipped nexus 16t sprocket. They are interchange between nexus and alfine sprockets but alfine only goes to 18t. Chain line now perfect but this is on a different frame with vertical dropouts (a Charge Duster Ti)

 

[Velonoir]

Thanks for that Kirstin, sorry to hear about the frame! I bought the last frame that On One had, as I bought a bike from them with a frame that was too small for me, so changed it for a bigger one, the original went in about a day on eBay.
I'll look up the vmi g ring, pleased to know the flipped ring works ok, thanks very much...Pete

 

[vfr400]

When you have horiz drop-outs, the massive torque from the motor can pull the wheel forward even when the nuts are done up tight. Have you got axle restraints or adjusters? If not, it might be worth bringing the wheel fully forward and using a tensioner.

 

[Velonoir]

That's a really good point, thanks a lot, not considered that, the axle is just in the dropout/trackends in the standard Shimano blue and green spacers. Was going to use chain tugs at one time, but never got round to it....Pete

 

[KirstinS]

That's a really good point, thanks a lot, not considered that, the axle is just in the dropout/trackends in the standard Shimano blue and green spacers. Was going to use chain tugs at one time, but never got round to it....Pete

Actually even with a front wheel conversion I found the chain tensioning a right pain and v regular on my old pompetamine

I was loath to go to a tensioner for pure aesthetics only (yeah I know) but when forced by a new frame with vertical dropouts I have utterly loved it ands would never be without now.

Though I've never coupled a bbs with horiz dropouts I can well imagine what a right pain that could be

 

[niggle]

Most references on the net give the Alfine 11 chainline as 41.8mm. If you flip a dished Nexus sprocket it moves the chainline out 5mm so you will get about a 46.8mm chainline. The Blingring brings the chain 4mm in compared to the standard Bafang's 50mm so you get a 46mm chainline, close enough with a 3/32", i.e. 6-8speed chain, no need for a chain tensioner. Chain tugs are a no brainer in this situation, I have to tighten the axle nuts on my Alfine 11 quite firmly without electric power going through it. Standard Sturmey Archer sprockets will fit (but obviously not the 1/8" thick ones, nor the the ones for the SA 8spd hub or the C50 hub). SA sprockets are very affordable and available in a similar range of sizes as Nexus sprockets.

However I would worry about your hub, it is not designed for this (Shimano now have brought out a new version with strengthened internals for ebike useage) and they can be a bit delicate, I would suggest considering an Alfine or Nexus 8 hub, I think you will find that adequate even in the Peak District with the Bafang mid drive.

My old Alfine 11 Pompino build:

 

[Velonoir]

Thanks Niggle, and what a super looking bike!
I fitted a reversed Nexus 20T ring yesterday, but had a heck of a job to get the retaining spring to fit, maybe the flange was just a tad thicker than the original, anyway I cut the plastic guard off the original, which after thousands of miles still looked brand new, and flipped that.
Also ordered a 42T PreciAlps chainring, looks very similar to the Lekkie but about 60% of the price.
Ironically, as it has an offset of 10.5mm, 1.5mm more than the Lekkie it may well need spacers the other way.
If I'd been starting from scratch, I wouldn't have chosen that hub, I'll have to treat it gently, I've never changed gear under power, and certainly won't with the motor.

One interesting point I read on a site yesterday, was that if converting a bike that is pre 2106 and has been ridden before then, it's legal to fit a twist and go throttle, The kit came with both twist and push throttles, but wanting to keep it street legal I've not fitted one.

Pic of the bike below, with the original smaller frame, and the hall sensor switch on the brake lever, held with sticky pad and tie wrap as a safety, magnet held with sticky pad and heat shrink, works a treat, and love the way a "brake" symbol appears on the display when the lever's pulled

 

[niggle]

I believe you can fit a gear change sensor, which will cut the power from the motor when you change gear. Maybe worth considering even if you have the good habit of not changing gear under load?

If the chainring you are fitting is further inboard by 1.5mm compared to the Blingring, taking it to 44.5mm, you could fit a flat sprocket on the hub which should give a chainline of 44.3mm, in other words ideal.

What size is your OEM sprocket? The Shimano guidelines for ratio is no higher than 1.9:1 so with a 42T ring the sprocket should be no bigger than 22T and that is for human power only. 20T sounds a good choice, cheap mod as well at £2.99 for a SA flat 20T 3/32" sprocket, postage £1.50: https://www.sjscycles.co.uk/sprockets/sturmey-archer-20t-sprocket-332-flat-hsl949/ With 42Tx20T you will get a 30" bottom gear, in Cornwall with a front hub motor I am finding the lowest gear I need is 36" which will get me up a 20% hill, all be it slowly, with only light pedalling effort.

If you do order the 20T flat sprocket do yourself a favour and order the SA circlip for 99p, it is round profile so quite a bit easier to fit and remove, but I have never known one let go in use, and it is handy to have a spare in case one pings off into the dark recesses of the garage when removing it! https://www.sjscycles.co.uk/hub-spares/sturmey-archer-sprocket-circlip-hsl721/

 

[Velonoir]

Thanks very much, fitting a flat sprocket's a great suggestion, cheap as chips too!

My Alfine chainring was 39 with 20 rear sprocket, ( the smallest/biggest they do specifically for the 11 speed, only 18 and 20 being available} initially I had a 44 but that was too high for the hills for me.

There was much mention in the early days of the 1.9 :1 ratio, but lots of mountain bikers seemed to have disregarded the advice without any harm, Having paid about £600 for the hub at the time, certainly erred on the side of caution.

I did contemplate a gear sensor, and still may do, I have the spare connector on the motor for one, which I believe cuts off for a shorter time than the brake sensors. Funny I get so used to not peddling whilst changing gear on the alfine that I sometimes forget, and stop on my Croix de Fer as well sometimes going up a couple of cogs, The 105 rear mech doesn't like it at all!

What chain tugs would you recommend please?

Thanks for all the advice and help, nice friendly forum this, so many are populated by folks who just want to show how clever they are!

 

[KirstinS]

Hey

Have a little look here

Chain tug for Shimano Alfine 8

Home › Forums › Bike Forum › Chain tug for Shimano Alfine 8 Search Overview Chat Bike Members News Women This topic has 18 replies, 7 voices, and was last updated 11 years ago …

singletrackworld.com

The issue is getting a tug that will work with alfine anti rotation washers

 

[Velonoir]

will do thanks, just ordered the sprocket and ring

 

[Velonoir]

One of the posts that you linked, had one from On One which with minimal filing to fit the anti rotation washers, only £3 each, look really substantial too