Is the spread of an Alfine with an 18T about the same as an 11-34 cassette? If so is it ok to run it with something like a 34 or 36T chainring?
I've got one of those Roadrat factory Alfines on order but I'm thinking that I'll probably want to lower the gearing to have something close to a 1:1 bottom gear.
yes and yes. Mine runs 32 and 18 and it is almost exactly the same as a 1x9 11/34 with a 32 chainring. No problem to raise it up a bit. I intend to by putting a 16 on it
Cheers. I'm not completely sure but I' expecting the Roadrat to have something like a 45 up front and while I'd be ok pushing the equivalent of 45:34 on my commute most of the time it's too high for those days when I'm knackered and the uphill homeward leg is straight into the teeth of wind and rain. It'd also be a bit high for any longer touring days with the bike loaded up.
[url= http://www.sheldonbrown.com/gears/internal.html ]Gear calculator[/url] so you can compare set-ups
the alfine crank is usually a 45, I think 44 is also available. I expect the bike will be supplied with a 19T sprocket which will give a bottom gear of 34", a little over 1:1. The easiest (and cheapest) way to get lower ratios would be to change the sprocket (they cost just a few quid) I think 21 is the biggest available (Shimano recommend maintaining min 2:1 chainring:sproket afaik) this would give a first gear of 30", nigh on 1:1
my Alfine-d roadrat has a 45T and (erm...) 19T out back I think and that is enough to climb almost anything except when fully loaded touring when I sometimes yearn for a couple more so I can winch up at walking pace!
Thanks for that. I'll have a look at sprockets when I get the bike (which won't be until the end of April by the looks if it).
I've got several spare chainsets and BB's which I could use, which is why I was thinking about that as an option. My current commuter is on 22/32/44 (26" wheels) and while I don't need the granny ring I do use 32:32 sometimes. I also use the biggest gears at times as well, but not for long enough that I'd miss them much.
