in Bikes and Gear

I'm looking for some thoughts on running my race bike with a 1x10 setup this year. Looking at combining a OneUp 42T sprocket with an XT cassette to create an 11-42 out back (same as XX1) with a RaceFace NarrowWide up front. Probably some sort of chain retention/clutch derailleur in there too.

Last year I was running a 2x10, 11-36 and almost never used the lowest gears on the smaller ring and spent the majority of my time in my larger ring.

Do you think this would be a wide enough range for XC racing?

Here's the website I used when I made the decision to go 1x. Just open two browser tabs, enter your current 2x setup in one, and your proposed 1x setup in the other. For the wheel and crank I don't think they have to be exact, just make sure they are the same for both setups.

http://home.earthlink.net/~mike.sherman/shift.html

an 11-42 out back (same as XX1)

XX1 actually is a 10-42 tooth cassette...that's why the need for the different freehub body.  A 10 tooth won't fit on the traditional SRAM/Shimano cassette carrier.  And a 10 tooth cog compared to an 11 tooth cog is a 10% increase in gearing...not insignificant.

At any rate, I ran a 1x10 with a 11-36 cassette and a 30 tooth ring and was never undergeared...except possibly on some fire-road sections of the Cheq100.  But I was tired and didn't really want to go faster anyway.  If you get the 42 tooth cog, you can go with a larger chainring and maintain your low end gearing.

Gary, thanks for that link! I put in the numbers I was looking at and the curves are pretty interesting to compare. I do have to note that I'm moving from 29" down to 27.5" so I'm sure that factors in as well.

Nate, I saw that difference very clearly on the graphs from the above-mentioned site. The 11T top speed was about 3-5 mph less with the 1x10 over my current 2x10. But, like you said, a front ring size change or increased cadence will make up for that.

You can set the wheel size, if you didn't notice.

My new trail bike (I don't race) is also 27.5, XX1 with a 28T chainring. That lets me get down to where I was with 2x, and it's mostly because of the climbs I regularly deal with. It's easy to swap chainrings and I might end up doing that for some places, but I want to see how it feels first before dropping any more money. I'm still on the fence about a top chain guide. I'll get the MRP AMG if anything.