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Im looking to upgrade my Fritzz to a 10 speed transmission, and i fancy, based purely on the fact that it looks kinda smart, going for a double ring at the front (XT M785) setup. Beyond looks (IMHO), which is a lame reason to buy alone, what other advantages exist over a traditional triple setup and what are the disadvanatges?
See previous discussion or arguments....
Basics you can get most of the useful gears from 2 rings by increasing the gap between the 2 rings. More like high low.
You don't grind the larger ring on the rocks and your leg. You can run a shorter cage mech and bash and chain device if you want.
Downside slightly bigger jump between rings and nice flat out road fire road gear.
As I see it the main advantage is to Shimano, Madison and the bike trade. They get to sell you another set of cranks and rings.
Waderider you just take 1 off and replace with bash. Loads of advantages to the rider.
Better clearance
Lighter weight
Fewer front gear changes
Can use all gear combinations
Less chainsuck
Downside slightly bigger jump between rings and nice flat out road fire road gear.
Depends on ratios.
As I see it the main advantage is to Shimano, Madison and the bike trade. They get to sell you another set of cranks and rings.
I've been running doubles for 7 years, with a variety of ratios (32/44, 30/42, 28/40, 28/42), only recently gone to double specific cranks (and now running 1x10), they don't really make a difference, but if you're buying a new chainset s
anyway...
OP: I'd say its about the ratios you want to run. I found a 22 of no use, and found a 44 a little tall so gradually tried smaller, which worked for me. If you find a 32 really good, or ride on the road a lot then changing to other ratios is a bit daft.
I started running doubles ages ago, before shimano or even sram started making them. I came to building a new bike and was just far too logical to waste my time with another triple.
Pros (in no particular order):
Lighter.
Cheaper.
Looks better.
Gathers less mud, easier to clean.
One ring for going uphill, one ring for going downhill = you never have to change whilst climbing or descending.
More even wear, as you're roughly in the big ring the same amount of time as the small ring, whereas in a triple you're in the middle ring 90% of the time, and it gets trashed quickly, which trashes your chain and cassette quicker too (which is another reason why it's cheaper).
Better gear ratios - I have what I need for climbing anything, and I have what I need for descending anything - I've spun out only a couple of times in 3 years or so. No pointless extras.
Can run a bash if you want.
Easier to set up.
And here's a gear ratio chart of a typical double vs typical triple set up, both with an 11-36 10 speed cassette. I run a 9 speed 11-32, so ignore the first column for that.
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Better chainline is another reason to go for the 2X specific crank. Essentially, the 2 chainrings are located where the gaps would be between the 3 rings on a triple. This means less of an angle when on the big or small cog.
Surely the chainline is worse when using either extreme end of the cassette on either the largest or smallest front chainring?
blisterman I think he is talking about when you're in big big or small small. There, the chainline is better then the equivalent in a triple set up. I would claim that you get a better chainline more often with a double, but wouldn't really put it as a massive selling point.
oh, yeah OK, I'll go along with that.
At the end of the day there really is very little difference; there may be marginal gains at the extremes but you pays your money, you makes your choice.
It depends very much on your type of riding and where you ride. Experiment if you can and make a decision that suits you.