# Double chainring on an Alfine



## EFMax (Aug 20, 2008)

I doubt that I am the first to do this, but after logging up some proper mileage on the Alfine I have now decided to experiment with a double chain-ring up front.









I started off from inception of the Alfine with a 38T x 18t setup, and this was good but I still wanted more.. so I have swapped my 38T ring for a 42T plus a 32T ring and together they weigh the same as my heavy 42T ring @ 160g (which is cool). And there are no issues with chain line or alignments.

I have fitted a basic Shimano top swing front mech @ 170g and an old style road derailleur lever at 15g to my seat post and hey presto, a really nifty setup that works.

I am not intending to be constantly shifting rings but I felt I needed more relaxed cruising gears on the flats to up-hills plus and an extra lower gear for the real nasty climbs. I also wanted a higher top gear for those sweet downhills.

Previously my gear inches range was 28.9 - 88.4 (38T x 18t)
Now it is (both rings) 24.3 - 97.8

A straight 32T x 18t or 20t is never going to work for me as I need that upper end for my downhill pleasure.

This effectively means (on the flat roads) that I can ride on the 32T ring from gears 3 - 8 (This is now much more evenly spaced out for my riding style, especially hill climbs (gears 1 - 3) and by switching rings for the nice downhills, I effectively have two more gear ratios (because gear 8 on the 32T is exactly equal to gear 6 on the 42T) which mean that I now longer spinout at 35mph plus when going silly down long hills or decents.. great, I am pleased as my weight increase is only 200g and this is offset by the fact that I changed my saddle for a more comfy one and the weight went down from heavy 675g to a light 320g.

I think this has now given me a very good working range for almost no weight penalty and I suspect this will reduce the wear and tear on my old bones as I was finding gear 4-6 not quite what I wanted or where I wanted it..


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## pursuiter (May 28, 2008)

I've been looking at a similar set up, except 22 and 36 in the front so I could have a 17 inch low gear for the really steep climbs. What about using a double cog in the rear and single ring in the front? Say, 16x23 in the back with a 32 in the front? Would take a little fabrication/welding but saves some weight.


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## EFMax (Aug 20, 2008)

Would not a double cog at the back be way too much effort and way off the whole Alfine framework.. A 20T or 22T granny ring on the front would give you an amazing low gear.. You are making me think hills in your area a way too steep.

Today I went up a hill which has a 10% gradient but is 800mts long.. for years I have avoided this hill except to come down it (just free wheeling down will let your bike reach an average of 36mph).. I attempted this hill today after a 30km bike ride and managed today sitting down all the way up and that was on 24.3 gear inches so 17 gear inches sounds like my legs would spin but the bike would hardly move.. sorry you can keep those steep hills to yourself..


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## pursuiter (May 28, 2008)

Just brainstorming. Since you already have a dual pulley chain tensioner and a shifter, it's not such a leap to a rear derailluier. I'd like as low a gear as the 26ers have 22x34 on a 26" wheel makes a 17 inch gear. Right now on my 29er with a 32x23 I have a 21 inch gear, a 17 inch gear is ~22% lower, that's alot!


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## orbealanza (Aug 9, 2009)

Hello,
I have installed my new Alfine few days ago. Loving it so far, just 70km on it. Now I am riding with a dual front chain ring (22-32) and the 20T cog. This gives a very low gear range.
But I am going to change to a 18T cog and 22-36 in the front. This will give me a large range with a very low gear for steep hills in the mountaing or when I travel with paniers and a fast top gear for fun downhills.
Next week I´ll put it on test on a 4 day trip with about 10 kg luggage.


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## EFMax (Aug 20, 2008)

pursuiter said:


> Just brainstorming. Since you already have a dual pulley chain tensioner and a shifter, it's not such a leap to a rear derailluier. I'd like as low a gear as the 26ers have 22x34 on a 26" wheel makes a 17 inch gear. Right now on my 29er with a 32x23 I have a 21 inch gear, a 17 inch gear is ~22% lower, that's alot!


Maybe a triple chain ring upfront maybe your answer.. in my head I am not too sure how or even if you could fit a double cog on the back of an Alfine, but a triple ring upfront say 20/30/40 with a 23t back cog on 29ers this would give you a range of 13.3 - 81.5 and that would more than sort you out..

There are some very light rings out there at the moment - this is what I am using - Gusset Tribal R Ring









Very strong and very light - 20t approx 25g - 30t approx 38g and 40t approx 95g - these are about as light as you can expect to get away with and I grind mine hard and still no wear or issues..


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## pursuiter (May 28, 2008)

EFMax said:


> Maybe a triple chain ring upfront maybe your answer.. in my head I am not too sure how or even if you could fit a double cog on the back of an Alfine, but a triple ring upfront say 20/30/40 with a 23t back cog on 29ers this would give you a range of 13.3 - 81.5 and that would more than sort you out..


I measured it out, a double rear cog can fit but takes some advanced metal fab skills. I don't worry about the weight at all, my bike weighs 33 lbs and I've lost ~40lbs since Feb, so my bike is effectively -7lbs, take that, weight weenies!

I am interested in the double cog in the rear for simplicaties sake. To run a double chainring in the frt I need a double pulley tensioner, that's a rear derailliuer minus the cable. The high gear isn't an issue for me, I can spin it to 25mph with a 68inch gear, I'm not interested in pedaling that fast. If the downhill zooms me to 35mph, that's fine. I don't want/need to pedal that fast.

Absent advanced metal fab skills, I'm think about your set up with a 36/22 up front and a 20 in the rear. Or I'll just keep getting fitter/lighter and see what I can ride up in my 21 inch gear.


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## EFMax (Aug 20, 2008)

Ok.. as I have the Alfine chain tensioner already (due to my bike being full suspension) I did not understand where you were coming from, but I do now.


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