Compact or Triple Crank?

[Veronica]

(I take that back if you live in CA and are MTB riding in the hills!).

SheFly

Yeah, I don't think I could give up my little ring on my mtb. I think I spend 90% of every ride in it.

Veronica

[jessmarimba]

I know the bf seriously dislikes the idea of 2x10 gearing for mtb. In his opinion, it's moving that way because that's what companies are making, and not b/c that's what people really want. But I'm sure it depends on where you're riding (and who you ask - but he's been riding for eons, so it's not like he's not in bike shape).

Personally, I wanted to go 1x9 before I got hurt and lost most of my leg strength. I was spending the majority of every ride in the same 2-3 gears. But...now I'm very happy with a triple

[bellissima]

limewave, are you sure is a 20/47? it seems like a very odd number, most double cranks ( what you call compact) start at 24 for the small ring and go up to 44 for the big ring. A size 47 will be too big on a mountain bike. A 20 teeth granny gear would be super easy (too easy) and a 47 would be too hard. Using a double really depends on the area you ride and you level of fitness. Here in SoCal most of the fast racers are using doubles and really like them, but you must consider that they don't use the granny gear at all so having it make no sense and they tend to ride bigger gears anyways.

[laura*]

limewave, are you sure is a 20/47?

I think she typoed: The El Mariachi specs say 27-40.


I wouldn't apply the term "compact" to any of the mountain doubles. If anything, they are the opposite of compact. Here are three types of mountain double:

1) A 22-32-44 crankset with the 44 tooth ring removed (and possibly replaced with a bash guard).

2) Like above, but with the middle ring replaced by a larger ring at the factory - perhaps 22-36.

3) True doubles meant for use with wide range 10 speed cassettes. SRAM seems to like the ratios 26-39 and 28-42. The FSA crank on the El Mariachi splits the difference at 27-40.

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In the 2000-oughts, the MTB industry settled on a 22-32-44 crank with a 9 speed 11-34 (or 11-32 for flat landers) cassette as optimal. The problem is that a lot of gear ratios are duplicated. There might only be 13 distinct ratios.

With the change to 10 speed cassettes, it is possible to provide nearly the same lowest to highest range while eliminating many duplicates by using 2x10 gearing. I'm not sold on this though - this change does lose the lowest and highest gears!

I think SRAM has a (old) patent on cranks with 1:1.5 ratio chainrings. They found that this jump provides for smooth easy quick shifting. (26 times 1.5 is 39!) This wasn't useful until the 10 speed generation 'cause the 1.5 ratio is just a bit too big for narrower range cassettes.

Shimano's DynaSys ratios also claims better shifting than before.

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The 3x9's lowest gear (22:34) is gone from the 2x10 system. The 3x9's next lowest gear (22:30) is almost the same as the 2x10's lowest gear (26:36).

At the other end, the 3x9's highest gear (44:11) is also gone from the 2x10 system. The 3x9's next highest gear (44:13) is comparable to the 2x10's highest gear (39:11).

And of course, those of us who are thrilled to use a 29er 36 tooth 9-speed cassette to provide an even lower gear on a 26er - well, we're left out in the cold.

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Do you need the extremes of gear ratios? Do you need to zoom down a highway to get to a monster climb?

[Aggie_Ama]

DH just put 2X10 on his Specialized S-Works Hardtail, loves it. I wish my Epic was 2X10. Why? I spend very little time in my big ring with the smaller cogs in the back which is what you lose the most. So less weight and eliminates parts I am not using. I would only need those for one race I am targeting training for that has a large road element to it. If I can save enough I will be adding a hardtail 29er with a double on it to my fleet. As Laura said, there is redundancy in the gearing that is taken away with 2x10.

Many of my Cat 1 friends are running 1x10 now, yes even several women.

[Becky]

I'm running a mock 22-32 double on my 26er, since I currently have the big ring "limited out". I can't say that I miss the 44 at all- I just don't use it. For me, the shifting gets a little weird when I'm in the 22 and the higher-geared half of the cassette, but I think that's a quirk of my particular frame. I will likely move to a 22-34 or 24-36 combination, and replace the largest ring with a bash guard.

Can you try out a double-equipped bike before committing to it?

[laura*]

I wish my Epic was 2X10. ... So less weight and eliminates parts I am not using.

I think this is an exciting time for bicycle drivetrains! In the past (or since Shimano invented HG gears) the emphasis was on simply providing enough ratios. Now in the 10-speed era the focus is on the quality of the shifting.

SRAM is rumored to be working on a whole line of two speed internal geared hubs. I could see them introducing a single chainring 2x10 system that gets the "10" from a cassette, and the "2" from the hub. SRAM hasn't been a big name in hubs - this way they may get more of their product on a bike.

Two speed cranks already exist, but they are expensive and rare. Currently bottom bracket standards are in flux. I could see Shimano making a cheaper two speed crank that uses a new bottom bracket design. That would be an alternate way to 2x10 gearing. Shimano's big enough to push through a change to frames' bottom bracket shells. This crank would keep buyers locked to Shimano's cranks.

Note that this is the first year of 10 speeds on lots of mountain bikes. (Last year's XX was for racers.) It might be a while before the optimal configuration is found.

[limewave]

After reading everyone's responses, I'm pretty excited to try the 2x10.