2x9 Cranksets for XC Mountain Bike Racing

There are three main reasons you should switch to a 2x9 crankset setup for XC racing.

1. Weight Savings

Two chainrings are lighter than three, so you save a little bit of weight. This can be a pretty big deal these days, with the availability of 20 pound full-suspension racing bikes.

2. Improved Chainline

With just two rings, you can have a straighter chain line in a wider range of gears. With some setups, you could use the small ring and small cog without the chain rubbing the front derailleur cage.

(With a triple chainring, or 3x9, setup, you can get crazy cross chaining going on, which is not a good idea.)

3. Lower Q-factor

This isn't a guarantee, but with some 2x9 setups, you can achieve a lower Q-factor. This means your feet will be closer together when pedaling, which can allow you a better feel and better power delivery to the pedals.

The biggest obstacle to a 2x9 conversion is finding a crankset. (You could just remove the small chainring, but that gives you a smaller gear range and doesn't improve chain line.)

So here are some options for you:

Cannondale SI

Cannondale offers a fancy 2x9 crankset made of carbon fiber. It comes standard on some of their finest bikes, like the Scalpel Team with the BB30. 29/44 rings.

Aftermarket, expect to pay about $1000 for one of these carbon 2x9 cranksets.

Website: http://www.cannondale.com/

FSA K-Force Light

FSA makes two 2x9 cranksets. The K-Force Light is the fancy carbon fiber one. It's available for regular and BB30 bottom brackets.

This one costs about $850 or more.

Website: http://www.fullspeedahead.com/

FSA Afterburner

This is an aluminum 2x9 crankset from FSA. It is similar to the other one, but cheaper since it's aluminum.

The 2x9 Afterburner will set you back about $300.

Website: http://www.fullspeedahead.com/

Middleburn Duo

The Middleburn Duo, whether you choose the RS7 or the RS8, is a popular 2x9 crank that has been around for a while. It has strong aluminum arms and is fairly light.

(The RS8 is basically the same crank arm as the RS7, expect it has some more metal machined off, giving it a slightly lighter weight.)

It's not too expensive either. The crank arms and rings (no BB) come in at $240.

Ring options include 27/40, 29/42, and 29/44. There is also the option to get either square taper or ISIS compatible arms.

Website: http://www.middleburn.co.uk/
Purchase: http://www.chainreactioncycles.com/Kits.aspx?ModelID=3345
http://www.chainreactioncycles.com/Kits.aspx?ModelID=3352

*Also, a "Shimano Spider lockring tool" would come in handy for the crank.

Stronglight Oxale Two

The cheapest option I've seen for a 2x9 crankset is the Stronglight Oxale Two. It is an inexpensive aluminum crank that has gotten mixed reviews, but Stronglight is a good company, so it is probably worth a shot if money is tight.

Website: http://www.stronglight.com/stronglight/page.php?nom=produit&keyProd=oxaletwo
Purchase: http://www.xxcycle.com/php/boutique/page.php?nom=PRODUITpp&key=4630

A few more things you should know:

Front derailleur setup

For the most part, you are using a standard front derailleur, but adjusting the limit screws and shortening the cable to where you just use two stops.

Then you just have to worry about the shifting issues caused by having a large gap between chainring sizes. With some setups, there is a good size jump/drop between the chainrings.

For example, in a 3x9 setup, the 32/44 jump is 12 teeth, but use a 29/44 on your 2x9 and you're dealing with a 15 tooth difference.

Bottom Bracket

The Cannondale and FSA cranks may include a bottom bracket, but with the other cranks, you probably need to buy a BB separately.

Make sure you get a BB that matches your frame. Mountain bike frames typically use a 68 or 73mm BB shell. A long spindle (such as 113mm) is usually required due to the wide chainstays.

One popular option is the Crank Bros Cobalt BB (ISIS compatible) for under $100.

You can see it here:
http://www.crankbrothers.com/cobalt_crbb.php

For square taper cranks, the Phil Wood BB is popular, although very expensive.