By Vernon Felton
Until recently, you've had two options if you wanted some of the benefits of SRAM's single-ring drivetrain system. First, you could pony up for a complete XX1 or X01 group and get the whole enchilada--fewer dropped chains (and by "fewer", I mean "really, almost none...ever"), greater simplicity and outstanding durability. We've written about XX1 and X01 so many times now that I will just say that if you haven't been paying attention, you should read Seb Kemp's long-term XX1 review here.
Or, your second option would be to buy one of the many narrow-wide-style chainrings (Race Face, Wolf Tooth Components, etc.) and pair that to your existing 11-36 cassette. The "grippier" narrow-wide teeth go a long ways towards reducing dropped chains when paired with a clutch derailleur, but if you live in the mountains or just aren't uber-fit, you'd soon find yourself wishing you had more of a granny gear to play with.
And that is where things stood. Until yesterday. Yesterday a new company called OneUp Components announced that their new 42-tooth cog just might make ditching the front derailleur a feasible, and affordable, option for the masses.
OneUp offers a 42-tooth sprocket that you can add to your existing Shimano or SRAM 10 speed cassette (see the chart below--you basically remove the 17-tooth cog from your current set up and add the OneUp monster cog and a spacer). End result? You could conceivably get that low, low gear out of a single-ring drivetrain without ponying up massive outlays of cash.
Let's do the math for a second. OneUp is selling their kit for $100. Add a Narrow-Wide ring (about $60) to that and you suddenly have a viable single-ring set up for not a lot of cash. If you don't already have a clutch-type derailleur, you can add another $140 to the tally. True, none of that is pocket change, but when you compare it to the price of going the whole SRAM enchilada, it’s a serious savings.
Does this kind of DIY single-ring system offer all the benefits of SRAM's set up? Doubtful. SRAM put a lot of engineering muscle into their XX1 and X01 groups--the chain and rear derailleur are both marvels all on their own--but, then again, a lot of riders have eyed the price tag on those SRAM groups and wished there was an alternative out there that was more affordable.
Those folks are going to be pretty stoked.
We can't speak to the durability of the OneUp cog. It's CNC'd out of 7075 aluminum and that's really all we know. We'll need to get one in our hands and start riding the thing in some proper foul conditions before we lay any verdict out, but I think it's fair to say that the single-ring trend could pick up serious steam once more people get on the stuff and realize that ditching the front derailleur is a beautiful thing, indeed.