As above really, chainline/cog availability means that I'll be running 34/20 on a Surly 1×1 to start with. I think this will be a little short. It'll be used as an off-road commuter in flattish Northants.

What do you run?

Ta, TR

32:20 for me, which on the road is way too low – not too bad off-road although I do run out of gears sometimes.

I'd be sticking a 44 or something similar on there if I was you.

btw – mine's a 456 with 2.35's on it, not a commuter.

32/18 on the iO ID seems about right for general off-road riding, 32/16 if you're fit or terrain is flat.

if you run an 18t rear cog the output essentially replicates the range of a 11-34t cassette, so running a 32-18 would be like running a 32-11/34. If you stick a 20t on the back its going to be lower so a 34t front ring would prob bring you towards the 32-11/34 sort of range.

34/20 is what I run for the Wiltshire Alps. Seems fine so far. Due to the split ring holding the sprocket on, I'd suggest swopping chainrings instead!

James-O – I thought the IO ID had a 36t chainring?

Either way, the stock IO ID gearing (which I thought was 36/18) seems just right for 90% of the riding I do. Unfortunately the Malverns are quite steep in places, so I popped a 20T on the back, meaning I can safely climb the hills but spin out a bit when travelling above about 18mph.

I now have 2 rear sprockets that can be easily changed on the Alfine, so I can tune it to the terrain as required (bearing in mind that changing the sprockets too much will require a different chain length – i've found that swapping between 18T and 20T on the back can be accomodated in the sliding drops outs without changing the chain length)

Ben

Anyone got an 18t gear in stock then? I don't think I can go much bigger on the front without the chainring fouling the chainstay or buggering up the chainline…

I'm also running an 18T – I only rode my bike for the first time last weekend at Cannock Chase and so its early days, but I think I've made the right choice. I think I bought the Nexus cog from here:

http://www.petracycles.co.uk/product_info.php?language=en&currency=GBP&products_id=5818&source=googlepbs

Thanks paper Lawyer, but can I ask a silly question? Does you cog look like the one in the picture? That one has a cassette style spline pattern and no plastic guardy thing, but it shows that other people have ordered them with Alfine hubs, so either I'm wrong (not for the first time) or the picture is wrong.

Ta TR

There are two types of sprocket that fit on the Alfine hub. There are the Alfine sprockets which have guides on them or Nexus sprockets which do not. The Nexus ones are dished so you can turn them round to get a better chainline if needed.

"James-O – I thought the IO ID had a 36t chainring"

sorry i should've clarified – it was 36/20 last year as shimano didn't offer a 32 crank with bashguard, in 2008 and for 2010 it's 32/18.

"The Nexus ones are dished so you can turn them round to get a better chainline if needed. "

yeah for mtb SS cranks with middle-ring positioned rings, the nexus dished outward to increase the chainline to 50mm works best. took a bit of faffing to get the CL on the iO right and this was the trick that did it.

32:18 on Mrs F's Alfine'd InBred, she seems very happy with it for general on and off road in the Chilterns. I rode it, and one of the gears in the middle seemed about right to me for offroad use (my InBred's a 32:16 SS 😉 )

If you get no luck at Petra, the guys at 18 bikes were very helpful about cogs (and the Nexus flip to adjust chain line) when I was building the Alfine.