Cycling UK Forum

Dan Joyce mentions an Alpine Double in his Facebook article

What's that then? Google's stumped

.

It's a double chainring chainset with a smallest ring somewhat smaller than you get on a compact (34t) chainset. 26/40 or something like that.

They are for people who think they are a cleverer arrangement than triples.

They are for people who want to lower the gearing on their double-chainset-equipped bike, possibly temporarily, without needing to make wholesale changes to the group set.

Small ring doubles were used in the 60s for touring in mountainous areas when almost nobody had a triple, or a rear mech capable of coping with the range. I certainly remember replacing my usual 48/36 with 40/26 for a tour. So there is nothing new in cycling, just reinvention.

With advent of cassettes with 11 or 12 toothed small sprockets, I realised that 40 by 12 is roughly the same top gear as my old 48 by 14. I have one machine with an "Alpine double" and 3 others with triple giving the same gear range. Where I might temporarily drop to the middle ring on the triple, stay on the larger ring on the double because that ring has almost the same range as the outer 2 on the triple.

We used to ride the big ring on a double (or triple) having the other rings for climbing. These days I read that on a triple you ride the middle as normal with the big one for going "faster!". So and Alpine double could be regarded as a triple with the outer thrown away because I am a pedaller not a pusher so have no need for gears over 90" or so.

Different ways of achieving the same thing.

My wife's bike had a compact double that, with a 34t smallest ring, left her struggling on steep climbs. I replaced it with an Alpine Double (28/40) that her existing mech could cope with (lowered down the seat tube a bit). The new chainset was a Spa triple crankset with the outer ring missed out and replaced with a black guard ring. Worked a treat and she found the new gear range ideal. What she lost (and never used anyway) was the ability to power along at high speed on long descents.

This sounds perfect for a bike I'm building for mountain touring

I love mountain touring - I've done end to end of Alps, Pyrenees, Dolomites, Japanese Alps, Spine of Italy and Canada to Mexico down the Rockies and I'm booked to do the Himalayas this year

I need a spinning gear for the climbs as I'm a twiddler, but like a bigger gear on the flat. I've got a 1x but have kept the chain ring small (26) to give me the spinning gears but it lacks the range for flat. I've got a triple but I don't like the complexity and weight on tour.

I've been considering a compact for the new (refurb) but the inner ring on traditional chainsets isn't small enough for long tours

I've been looking at the 46/33 on the Spa website but haven't looked at derallieurs yet - which one would cope ? Preferably on a Sram or 105 shifter

Or better still the 26/40 mentioned or even a bigger outer? Is the difference too big? I custom built my last triple and thought that you could only have an 11 or 12 tooth difference between the rings?

mnichols wrote:This sounds perfect for a bike I'm building for mountain touring

I love mountain touring - I've done end to end of Alps, Pyrenees, Dolomites, Japanese Alps, Spine of Italy and Canada to Mexico down the Rockies and I'm booked to do the Himalayas this year

I need a spinning gear for the climbs as I'm a twiddler, but like a bigger gear on the flat. I've got a 1x but have kept the chain ring small (26) to give me the spinning gears but it lacks the range for flat. I've got a triple but I don't like the complexity and weight on tour.

I've been considering a compact for the new (refurb) but the inner ring on traditional chainsets isn't small enough for long tours

I've been looking at the 46/33 on the Spa website but haven't looked at derallieurs yet - which one would cope ? Preferably on a Sram or 105 shifter

Or better still the 26/40 mentioned or even a bigger outer? Is the difference too big

When I was doing this I looked at the tooth difference the mech was designed for, then roughly replicated that but with a lower range. I was aware that I might have problems because the mech is curved, and the curve is related to rings of a certain size. By going below that size I was making the mech shape less than ideal. But I was lucky and it worked. I just kept the same sort of outer/inner tooth difference (12 in my case). The outer guard ring ought not to be much bigger than the largest ring in what would normally be the middle ring position.

The built for cyclocross Shimano FD CX70 is contoured nicely for smaller (40-46) big ring doubles. Shifts odd triples too.

Edit

Valbrona wrote:They are for people who think they are a cleverer arrangement than triples.

There used to be one compelling reason for choosing an Alpine double; it was easier (not to mention cheaper) to set up a bike this way. When the alternative would be a triple system that would be difficult to source the parts for, and be a bit finicky once you had built it, it seemed appealing.

BITD you could get the gears working well enough using common or garden derailleurs, and something like a stronglight 99 with a 28T inner chainring would give much lower gears than you would otherwise easily find. Spend a bit more and get TA cyclotouriste setup if you wanted even lower gears.

Years ago I built a bike for the GF that had a 28,46 chainset and a 14-28 block; this did very well for touring for quite a few years. It didn't cost a fortune to build, either, and would be easy to repair/maintain, since it used standard derailleurs etc. The plan was to fit different mechs, BB, and an additional chainring to the same crankset if a triple setup was required (not that this ever happened).

These days there is a similar attraction, inasmuch as there is plenty of choice in double STIs and not so much in triples. But against that, the situation regarding other component availability is almost reversed; derailleurs with a large capacities are easier to find, whereas suitable chainsets for an alpine double are not easy to find or very cheap; folk often use a triple chainset with no outer ring to get an inexpensive alpine double....

For touring, I'd sooner carry the extra 100g in a triple, not bother with STIs at all anyway, and have a few more gears /an easier shift pattern.

cheers

Brucey wrote:folk often use a triple chainset with no outer ring to get an inexpensive alpine double

40/24 TA rings on Campag Record cranks

I spent much of my cycling in the 1980s and 90s with a double 52/36.
That was "alpine" enough for me.