Written by Wally Wallace Tuesday, 09 July 2013 13:48
Are narrow wide chainrings and clutch style rear derailleurs the ultimate XC single ring setup for 1X9/10/11 speed drivetrains? Boy that's a mouthful...and sure to be up for debate. We bike nerds here at Bikeman World HQ spend a lot of time thinking about (and riding) such things. Some recent developments in drivetrain componentry, namely narrow wide chainrings and clutch style rear derailleurs have changed things for the better. If you’re not hip to that groove read on my friend, professor Bikeman is here to educate.
Lets start with the newest development first: the narrow wide chainring. When SRAM released their latest MTB group, XX1, it became the 1st top of the line XC racing group to use a single ring up front. It also uses a 10-42 cassette making the range of a their single ring setup huge, but I digress. Lets focus on the salient features of a narrow wide chainring. It’s pretty straight forward - half the teeth are wider and look a bit like a plus sign, half are narrow. By alternating between these two tooth profiles you have a chain that better fits the hollow parts of the chain resulting in a more snug fit that retains the chain when the going gets a little rough. Previously only available for SRAM XX1 or from small boutique manufacturers, Race Face recently released a full assortment of 4-bolt, 9/10/11 speed compatible rings in 30t, 32t, 34t,36t, & 38t. The 30t version is something we're pretty psyched about and a it's pretty cool how they did it. Take a look at the image below...there are two cool things going on with the bolt holes there that made it possible to fit a 30t on a 104bcd 4 bolt crank. On our east coast trails we don't find ourselves spinning out all that often so the extra 2 teeth for the low end is great!
The other less recent development in component land is the advent of the clutch style rear derailleur. Of course, SRAM (type 2) and Shimano (shadow plus) had to make up their own names but they accomplish the same things: virtually eliminating chain slap and dropped chains. In short, the clutch limits chain movement by applying a higher degree of tension on the chain as it runs between the bottom of the chainring and lower pulley wheel than a conventional derailleur. It also stops the derailleur cage from rotating forward, thereby de-tensioning the chain, when the going gets rough. Both styles have a switch (Shimano) or button (SRAM) that makes it easier to take the rear wheel off. SRAM offers these derailleurs in X9,XO, & XX1 versions. Shimano offers them in XC/Trail Mid and Long Cage version in SLX, XT, & XTR and more gravity oriented Zee and Saint short cage models. You can find them all here. For most applications we prefer the shortest cage possible. So save some weight, quiet down your drivetrain, get better clearance, and drop fewer chains by adding a narrow wide chain and clutch style rear derailleur today. You won't regret it.