: 2×9

By: g | No Comments » |

Okay, I know what you’re thinking, why would anyone bother with a 2×9 set up on a mountain bike, after all, aren’t they supposed to have a granny ring? Well yeah, but there are some subtle advantages with ditching the granny ring. And besides, this is simply to help out those who may be interested in setting up a 2×9, if you don’t wanna try it, don’t read it!

Why did I do it?

The way I set my bikes up is quite dynamic. Nothing stays too much the same for any length of time, I’m just one of those tinkerers. I did this as an experiment, as all I needed was a 29-tooth chainring it wasn’t going to be costly.

Also, I found that I’m a bit of a wuss on hills, I’d change to the granny ring all the time whether I really needed to or not. I knew I should be using my gears more wisely, and I figured that this might help.

You lose the full range of gears of course, but it allows to better use the spread of gears you have. Confused? Good

What do you do to go 2×9?

Well, you lose the middle and granny chainrings, to replace them with a chainring that is smaller than the middle, normally a 29 tooth.

Assuming you already have a 9-speed drivetrain, you don’t need much at all. In fact, all you need is a smaller middle ring. I use a 29 tooth 5 bolt Ritchey chainring. I don’t know what is available in 4 bolt in that size. Maybe you’ll need to chase up a 5 bolt crankset as well? I have some old STX-RC cranks where the granny ring bolts to the middle ring, they’re prefect for the task.

In terms of your cassette, get something with RANGE! My preference is for a 11-34. A 29-34 is basically the same gear as a 22-25, so you�re really only losing the lowest 5 or so gears.

Do you need to run 9 speed? No you don’t, but bear in mind you are losing your lowest gears so you want to have as big a sprocket on the back as possible, and as such the 9 speed gives you that range. I wouldn’t run 2×8 because I’m not a hill freak, and I do ride in the hills. I know someone who does though, (Hi Justin) he is younger and fitter than me. Many people are though.

You may need to go to a bottom bracket with a narrower axle, more about that later.

How do I set it up?

Bolt up the new chainring where the middle ring once sat, and if necessary, put on your shiny, new 11-34 cassette.

The front derailleur is the next adjustment. You want to lock out the granny ring position, so put chain onto the small chainring and onto the largest rear sprocket. Find the low adjustment screw on your front derailleur and adjust it so that it the inner plate of the cage sits a couple of mm in from the chain. You’re making ineffective the low gear position of the shifter, it will still click to that position but you’re preventing the derailleur cage from moving when you do so.

I had some problems with the chain falling off the small chainring in the lowest gear position. This is because the chainring that’s now in the middle position is substantially smaller than the largest rear sprocket. Normally not a problem with a normal 22-tooth chainring in the granny ring position because of a straighter chain line. In order to improve the chain line I had to install a bottom bracket with a narrower axle. Warning, if you need to go to a narrower bottom bracket axle, be careful it doesn’t result in the big chainring hitting the chainstay!

What are the advantages of a 2×9?

The weight saving. Bwahahaha, yeah right. Maybe if you’re an anal-retentive gram counting weight weenie. You’re saving the weight of the middle ring basically, so hardly worth the bother in the scheme of things. But this isn’t about weight saving. The real advantage is the gearing. Okay, you lose some low ratios, but all up you get smarter use of your gears. In a 27-speed set up, if you were to measure the distance the bike travels for one crank revolution in each gear, you would find a lot of duplication. A 2×9 just makes for less farting about with shifting.

The main advantage is you tend to tackle hills with more determination. You find yourself pushing through a slightly bigger gear than you normally would. Besides, if the terrain wins you have an excuse. I use 2×9 on my hardtail, which is a bolt or two over 11kg and very stiff and responsive. So I can get away with that gearing on such a nimble bike despite being ummm, pretty bloody average.

Disadvantages?

The set up can be a little finicky. And you lose your lowest gears. Finding the right inner chainring may be hard. Oh, and answering questions as to why you’ve bothered.

Do I like it ?

Yes. A lot. I’ve cracked my first 100km day on dirt with that set up, and I use it in the 12hr and 24hr races. I find the gearing to be quite user-friendly and the chainrings are easier to keep clean. It’s well worth mucking about with.

Hope this helps, enjoy!
Glennnnnnnnnn

Dr’s note: I have run a 2×9 on and off for a while, except before Glennnn’s wonderful explanation, I ran it with a 34/36 x 9. Hard work. That said with a 29 instead of a 34, it should be a breeze. The 2×9 setup is clean and simple and if you ride a lot, you most probably do not use the granny much in anyway. With a 29 you’ll be set. I fully recommend it….

 

Tags:2x9,gears


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