Hi folks, first post from a new Stooge (mkI) owner.
I’ve just finished setting up an Alfine 8 speed rear hub on mine after running it as a singlespeed for a few weeks as I couldn’t quite find a satisfying compromise gear ratio-wise between riding on flat roads and then trying to haul up the hills off road.

Anyway, a bit stuck getting the optimal set-up with the hub, the chain and the eccentric bottom bracket.

I cannot find an optimal chain tension at all. Just running through it with some old chain (I checked, barely 1/16th stretched) and I can either join the chain, with the BB set back at 9 o’clock at what I’d describe “angry banjo wire tightness”, or with an extra link and the BB at 3 o’clock, just a bit too slack to ensure it’s not going to pop off. There’s about 12-15mm of vertical movement then. With a new chain I’d probably be there as it’d be a couple of mm shorter, but the bottom bracket is forward and up of where I want it in that 3 o’clock position. Ideally somewhere in the 6 to 9 o’clock range would be great.

Given I wouldn’t mind a tiny bit higher gears- could I leave the chain as is and then buy a chain ring with, say, 1 or 3 more teeth for the front and that’d let me swing the BB down (to shorten the chainstay a touch) get it where I want and make my gears slightly taller?

Advice much appreciated.

Your best bet with an EBB is between 12 and 3 really – your weight is pulling against the chain tension.

Maybe try a half link on an 8 speed chain?

What waswas said, around 2 o’clock (viewed from the drive side) works best balancing chain tension against your weight. Although 8 o’clock works equally well (your weight works to tension it there and the chain tension to slacken it). It’s a moot point if the EBB isn’t slipping, but best to pick one of those positions for belt and braces.

I’d fit a fresh chain and see if that solves it. Chains don’t wear evenly so worn chains make setting tension a PITA.

Chains should generally be slacker than a lot of people have them. They need to be tight enough that they don’t fall off, not starting off at banjo tension and backing off until it lets things move! I’ve never lost a chain through a lack of tension, but regularly have to defend my visibly sagging chain to people commenting that it’s too slack! Just make sure the chainline is correct and use a decent singlespeed chain like KMC Z610 3/32 which won’t twist.

could I leave the chain as is and then buy a chain ring with, say, 1 or 3 more teeth for the front and that’d let me swing the BB down (to shorten the chainstay a touch) get it where I want and make my gears slightly taller?

Yes. Simplest solution, no EBB or slider dropout can cover every ratio equally. There shouldn’t be any need to position it based on your weight and leverage if it’s an effective / secure EBB.

I ran my alfine bike with a very slack chain most of the time – 30 mm slack was not uncommon before I tensioned it. With unramped teeth and a good chainline it won’t come off

Thanks folks. I say and played with it for over an hour the other day and was sure I was missing a trick- the sanity check is really useful.

Hadn’t realised position could be a factor, resisting pedalling forces etc. It didn’t budge as a singlespeed but useful knowledge to have in the back pocket if I ever find it’s not doing so in the future.

I’m going to order a new 3/32 chain and a 19 tooth nexus/alfine rear sprocket. First port of call will be to see if I can get that lower BB position (and I’ll aim for 8 o’clock now) with one less tooth but, if not I’m happy with it further forward if the chain tension is better. There are so many variables on a bike, not going to sweat it too much if it’s not “perfect”.

Thanks again.