The relative offset between front and rear cogs should of course ideally be zero.

For an unforeseen reason I can't get as close that that as I had hoped without some major surgery.

Then again a 1x derailleur will have quite some offset when in highest or lowest gear.

 

I'll tell you the particulars, but first you tell me how much is too much

It's too much when the chain keeps coming off the chainring.

If that happens on a fixed chain it could get ugly!

I'm using a KMC X9-93 chain on a 32t Bling Ring in front and a 22t on the SRAM 5 sp. in the back.

As the OP rightly said,if you use a 9 speed cassette like me ,the chain canbe nearly an inch out of line in top and bottom gear.

I use a standard chainring and 9 speeds and have never had a problem and most of my riding is done in top gear ..

Well, that is reassuring.

As close as I can tel that's exactly what I have. 2.5cm out of line.

 

It's possible to flip the cog on this hub to gain about a cm on that, but then the chain rubs against this "intermediate chainstay" I have on my frame.

 

 

I have the feeling this is really just for show, but I'm still a bit hesitant to take a hacksaw to it!

Just give it a try,I would expect it to be OK at that .

I certainly will once my battery arrives

Well, that is reassuring.

As close as I can tel that's exactly what I have. 2.5cm out of line.

 

It's possible to flip the cog on this hub to gain about a cm on that, but then the chain rubs against this "intermediate chainstay" I have on my frame.

 

[ATTACH=full]19034[/ATTACH]

 

I have the feeling this is really just for show, but I'm still a bit hesitant to take a hacksaw to it!

 

Sorry if I'm being foolish but do you hub gears (like photo appears to be) or deraileurs?

 

I have a feeling I am missing something here!

 

If you have hub gears then a singulator or tensioner can help

A singulator! That's a new one to me.

I will keep that in mind if I have problems.

Something like this

 

Look at this on eBay:

 

https://www.ebay.co.uk/itm/222090024643

 

Single Speed Converter Chain Tensioner MTB Bicycle Singulator Seeker Red Red

Exactly. But at the moment I have less than an inch of play. The frame is built for hub gears after all.

I guess I could make a couple of tensioners like this if I wanted it still tighter with more fine-grained control.

 

 

On the other hand the spring loaded tension provided by a singulator could be qualitatively different in some way I've not realized yet.

I have an Alfine 8 with a BBS02. With the alfine rear sprocket you can flip (plastic cover is then on the inside) it so it sits further from the wheel making a cleaner chainline. I have a couple of chain guides left over from other builds. One is a Gusset that sits in the old derailleur hanger and the other I have up near the chainring.

I use a singulator on another, non-electric, bike and difficult to fit but very good once done.

 

This is the gusset:

http://www.chainreactioncycles.com/ch/de/gusset-bachelor-ss-kettenspanner-/rp-prod17724

 

And I have one of these up near the chain ring

http://www.chainreactioncycles.com/be/en/brand-x-chain-tensioner/rp-prod10137

 

This setup works well for me (I have a dodgy damaged BBS02 also so the chainring is at a bad angle to start with).

 

For you you would probably do alright with the singualtor, it is a bit pricey but works.

http://surlybikes.com/parts/drivetrain/singleator

Thanks for the info. I'm certainly learning about new options here.

What I find slightly confusing is that I have horizontal dropouts, so I can make the chain as taut as I want, but you write as if it's self evident that a singulator would be better.

Are we just talking past each other a bit here, or am I just not aware of why these spring loaded options are superior?

Yeah i have angled dropouts not horizontal. The bike was originally a mountain bike with derailleur gears. I thought for horizontal you could use a BMX style chain tensioner. Google throws up loads. I think they work by pulling the wheel back. Not sure if it would work in your situation or not.

 

The spring loaded things are more for converting derailleur type bikes to single speed in my experience.

Thanks for the info. I'm certainly learning about new options here.

What I find slightly confusing is that I have horizontal dropouts, so I can make the chain as taut as I want, but you write as if it's self evident that a singulator would be better.

Are we just talking past each other a bit here, or am I just not aware of why these spring loaded options are superior?

 

In my mind (and im no engineer) the difference is the you set chain tension with horizontal drops. Once done real world influences such as chain stretch , big bumps and rattles of actual cycling can only mean increased chances of. the chain jumping off/slip. Riding can only in the setup deteriorating over time

 

In my own words a "passive" solution

 

A singulator /tensioner is, again just my words, an "active" solution in that it should respond to the changing variables around it (e.g. Chin stretch) and maintain tension. Setup shouldn't deteriorate in the same way

A singulator /tensioner is <snip> an "active" solution

 

Yeah, that was my first thought too.

 

But I finally had the chain guard in place yesterday and went for a short ride ( without power ) and there were no ugly sounds or other signs of trouble even when going up a steep slope in first gear.

 

My battery is arriving tomorrow, so I guess I will know how it all turns out rather soon.

I guess I could make a couple of tensioners like this if I wanted it still tighter with more fine-grained control.

I hope that's not your bike. the chain joining link clip is on backwards.

 

It makes little difference whether you use a tensioner or adjustable axle locks, although I think a spring-loaded tensioner is better because you don't have to keep adjusting it.

I have the BBS02/Alfine 8 IGH set-up and had to use a tensioner, no other choice really as the frame has vertical drop-outs.

 

 

I would say your problem is that 32t front bling-ring, is it specially for the BBDHD motor or the BBS02 or something you found? I know the offsets are different and if it`s not right you`ll get it dumping the chain off.

 

Try the standard item and see how it goes.

You could say the problem is the 32t bling-ring. The original Bafang 46t massive steel Frisbee from hell "wraps around" the final drive gear much further and provides a chain-line with with possibly just half of the offset. However the bike came with a 34t chain wheel and considering the heavy cargo and hilly terrain around here I don't really want to go in that direction.

If I encounter problems under load with the motor, I think I'll try a singulator first, and then see if I can get that "intermediate chainstay" changed a bit so I can flip the rear cog.

I used a normal derailleur to tension and line up the chain on my Nuvinci. It has the advantage that it's side to side alignment is adjustable. No need for a cable, just use the end-stop screws to adjust and hold it in position.

 

http://i451.photobucket.com/albums/qq236/d8veh/GNG%20Gen2/gng24_zps30340c00.jpg

I used a normal derailleur to tension and line up the chain on my Nuvinci. It has the advantage that it's side to side alignment is adjustable. No need for a cable, just use the end-stop screws to adjust and hold it in position.

 

http://i451.photobucket.com/albums/qq236/d8veh/GNG%20Gen2/gng24_zps30340c00.jpg

 

I might end up doing the same with my Nuvinci build, like the looks of no derailleur but function should always come before form!.

 

What chain do you recomend?, would like something as heavy duty as possible really..

Just for the record, now that I've had the bike in daily use for a few months.

 

I was *almost* able to make it work with 2.5cm misalignment.

With a freshly tensioned chain, and normal riding it would all work fine.

The missus never had a problem.

Riding harder on a bumpy road would cause a derailment sooner or later.

If it happened once, it'd happen easier the next time, and so on until I re-tensioned.

 

I just installed a tensioner off eBay with a simple custom mount, and now I can do bumpy roads under power without worry.