Alfine Chainline

[marcw]

Hi, I need to change the chain set on my alpine equipped bike but am really confused by chain lines. I've looked at the Shimano s500 Alfine Crank and it has a different chainline to the hub. The hub spec says 42.7 single or 49.2 double. The hub' s specsheet says the chain line is 41.8. The crank I have on there is 42mm.

Seems odd that the Alfine chain set has a different chainline to the Afine hub, also odd that it comes in double or single options. I can't work out what the Alfine crank is for?

 

[MacB]

you can get 3 chainlines on the hub, the usual narrow one which is what you'll have if you have a sprocket with the chain guide. A middling one if you use a dishless sprocket and a wider one if you use a dished sprocket flipped. As far as I know the latter two aren't an option with the little plastic bit on the outside of the sprocket.

On the crankset I'd guess that it's following standard Shimano Hollowtech II road specs. So you're a bit limited re the two piece drive crank and fixed axle length. The 42.7mm sounds like the inner of a road double, and the 49.2mm I'd guess is putting the ring in the outer position of a triple with a guard in middle ring spot and the other guard attached to the ring. It may be possible to fine tune chainline via spacers between BB shell and the BB cups, depending on how long the threads are and how man spacers are installed as standard.

Sorry I started to look into it more but decided against an Alfine chainset as they only do 170mm cranks, then I decided against and Alfine hub so it was moot anyway. But the above is what I gleaned from a first pass, search a few of the threads here, CTC, YACF and MTBR.com has a good forum secion devoted to hub gears.

 

[marcw]

thanks, it looks like I'll be better of sticking to standard Track chain sets with a 42mm chain line, I'll pose he question to Shimano anyway to see what they say.

 

[Piemaster]

Hi, I need to change the chain set on my alpine equipped bike but am really confused by chain lines. I've looked at the Shimano s500 Alfine Crank and it has a different chainline to the hub. The hub spec says 42.7 single or 49.2 double. The hub' s specsheet says the chain line is 41.8. The crank I have on there is 42mm.

Seems odd that the Alfine chain set has a different chainline to the Afine hub, also odd that it comes in double or single options. I can't work out what the Alfine crank is for?

.2 mm. I wouldn't worry about it over the length of the chain (or .7mm if its 42.7)

Think my Pompino has 42mm crank (track chainset) and a nexus 22t sprocket on the hub. Looks ok to me. And think about how much a deraileur can vary the alignment of chainwheel / sprocket, a chain is quite capable of handling a bit of misalignment.

Looking at the Alfine crank specs its available in 39 or 45t with either a single or double chainguard. Can't say I can be of any help figuring why the differences though.

 

[cycleoptic]

I am also having problems fitting an alfine chainset onto my commuting bike, a custom built bob Jackson, 531 frame with wide stays on rear to clear 35 tyres and mud guards.

The alfine bottom bracket is not long enough so that the 39 chainring clears the bike's stays.

Shimano do not do longer!

Any suggestions? Such as a track front chainset?

Steve