Currently got an Alfine 11 combined with a 40t chainring and a 18t sprocket.
This gives me a low of 31.3 and a high of 128.0.
Which I'm not too keen on. Going to change the rings, but not sure how low to go (And don't really wanna spend a fortune on trial and error chainrings...).
What numbers would be good to aim for?
Bottom of 20-25" is where you want to be aiming - much below 20" gets silly...
Loaded, unloaded? Alpine passes or the Fens? If loaded and in hilly terrain + long days, I'd go for the equivalent of 22 front/34 rear as your lowest gear. Alfine has its own minimum and this may dictate how low you can go.
Loaded. And both hopefully.
Alfines minimum is a 1.9 ratio.
A 38 - 20 would drop it to 26 inches.
I don't get the Alfine ratio of 1.9 is that something to do with ring:cog ratio.
Leaving that aside would you be better to up the cog/sprocket size instead of reducing chainring size? Iirc this should give improved efficiency for the same gear inches???
Yeah, ring/sprocket ratio.
As far as I understand it the 1:1.9 ratio means you shouldn't put a chainring that is < 38t if you have a 20t sprocket on the back.
Ah thats helpful. If thats the case then that presumably dictates the lowest gear you can get from the Alfine set up as the impact on gear inches results from the ring/cog ratio not the absolute size of them. Or is it different for a hub gear. Sorry for hijack just interested in the whole hub gear thing.
Bah, you've lost me.
Sorry on your original post my father (seasoned tourist) uses 46t outer and I think 24t inner with circa 28/32out back depending on which bike. Thats with 700c and 32mm touring tyres. Think that gives something not far from 20". Doubt he has used it much except when loaded fully loaded in the hills.
Ah, I think I get what you mean now.
I'm going to say yes. 😆
The smallest I'm going to get while sticking in the 1:1.9 ratio is about a 26-28' bottom gear. Might be able to get away with this.
Reading a few things where people have went outside this ratio and been fine though.
On the ratio thing in my earlier post.
Gear inches are traditionally calculated as:
Chainring teeth [divided by] sprocket teeth [multiplied by] wheel diameter
The rear wheel goes round one time for each full turn of the sprocket. So the first bit of the calculation tells you how many sprocket turns you get for one full turn of the pedals. The rest shows the impact of larger or smaller wheels.
If the first bit has to be 1.9 then I think that means this will dictate your lowest ratio (after the relevant multiple for the alfine's internals). Eg you cant have 36:20, which would be lower (1.8) but you can have 40:20
Sorry post above superfluous now and probably too much detail too.
Whether it's suitable depends on; how strong you are, how far you're cycling each day, how much you're carrying and how hilly the landscape is. Also, if you're going somewhere really windy, you should consider that.
It's easy to be all macho about lowest gearing but if you're putting in long, hilly, loaded days, day in week out, you'll need low gears. If it's just weekend credit card touring, you can get away with murder.
Half way through a 'significant tour' with a massive headwind and a 30 mile 9% climb ahead, you'll be glad you went lower. My 'standard' lowest is 24/32 and my lowest 22/34, I do run a 20/34 on the tandem for really beastly terrain 🙂
I reckon I'll pop a 20 sprocket on there and in time a 38 Chainring.
Does anyone know if I can put any old single speed sprocket on the Alfine?