It seems as though everyone is holding their breath waiting for Shimano to release their 1 x 11 speed drivetrain. With a few leaked 2015 XTR component pics online, it seems to be a sure thing for next season. In the meantime between forking over significant amounts of money for a dedicated SRAM X01 or XX1 drivetrain, there is a great option from One-Up components as well as Wolftooth components. The 42 tooth cog that is an add on to a standard 11-34 or 11-36 XT or XTR cassette. This gives you the same granny gearing as the SRAM offerings and allows you to run your Shimano components.
There are a number of benefits to this system and remarkably few downsides:
- Much simplified drivetrain: Shifter, chain guide, derailleur, cable, mounting brackets, extra chainrings–all eliminated
- Quicker shifting through full range of gearing: no shifting front rings, you can shift right from high gear to granny in one motion.
- More reliability: Not speaking of long-term reliability of the new front ring from North Shore Billet and the One-Up rear cog, fewer components and moving parts means more reliability in the real world.
- Lighter set-up
- Quieter drivetrain: There is no longer a front derailleur cage for the chain to rattle against, a definite plus.
- Perceived increased wear due to one ring, TBD, but the single front ring replacements are up to 50-100% wider than multi-ring designs. This means much more material and lower contact pressure and less wear compared ring-to ring.
- Shifting performance. The new 42 Tooth One-Up ring has ramps machined into the surface to aid in shifting, but to adapt the drive to reach the largest cog, the B-tension has to be adjusted to push the guide pulley back, this causes a larger than normal distance between the guide pulley and the remaining cogs, resulting is “softer” shifting. No difference in shifting was noticed as a direct result of removing the 17 T cog.
- Slightly narrower gear range choice. By eliminating the 24 tooth small ring and 38 tooth big ring up front, you cut off the high and the low end of the available gear range. This is described below:
Old Granny Combo: 24f – 36tr: This is a 1.5:1 reduction.
New Granny Combo: 32f-42r: This is a 1.3125:1 reduction.
What this means is real world terms is that with the new 1×10 drivetrain, the new granny gear is 14% “harder”
Since I never use ultra low granny, this new granny is equivalent to running in 24-32 on the old drivetrain. This is perfect.
Old High Gear Combo: 38f – 11r: This is a 3.45:1 Speed up ratio(Overdrive)
New High Gear Combo: 32f-11r: This is a 2.91:1 Speed up ratio (Overdrive)
This means that now the High gear is 19% “Easier” than with the old system. This is equivalent to running 38-13 on the old drivetrain (second smallest cog) not much of a compromise, unless you find yourself spun out in the 38-13 regularly.
To install the new 42 tooth rear cog is very straightforward, this involved basic bike maintenance tools: A chain whip, cassette locking sprocket and a wrench. The One-up sprocket is supplied with a spacer to make installation to either a SRAM or Shimano cassette possible with the same part.
To accommodate the new ring, you have to remove the 17t cog and spacer. This is the last individual cog on the cluster.
Now for the front ring. I picked up a North Shore Billet 32 Tooth chain ring from Republic Bicycles in Squamish. this is mounting on the 2x XT crank and since the existing crank uses two bolt circles for the two rings, the chain ring bolts are still suitable. Sometime with a 2x to 1x conversion, the bolts are too long and a new set is required, but not here.
A simple removal of the existing rings and installation of the new 32 tooth single is all that is required. I did remove the crank to gain access to the front derailleur and chain ring bolts. All that is needed here is a 5mm allen key, rubber mallet and a Shimano crank tool to remove the bearing preload capscrew.
The NSB ring utilizes the same technology as the SRAM and Race Face rings, where they have a narrow tooth followed by a wide tooth. This takes up the room in the alternating chain links between the inside and outside links. The effect is a much tighter chain fit and a more stable chain retention when not using any chain guides. I have not personally run this yet, but stay tuned for a first ride impression soon.
After removal of the derailleur, ISCG mount, cable, derailleur mount and shifter it really cleans up the handlebar and simplifies the bottom bracket area of the bike.
The rear derailleur B-tension screw requires adjustment to have the guide pulley clear the 42 t cog. To accomplish this you have 2 options, 1 to replace the screw with a sufficiently long enough one to allow more adjustment rearward or 2- to remove the small plastic spacer and tighten the screw until it bottoms out. I chose method 2.
With all of the clutter removed from the bike and handlebar, I was able to run my Reverb remote on the left hand under-bar side, right next to the grip. This really balances the cockpit out and lends to a much cleaner look.
All in all, for an extra $150 (42 tooth and 32 tooth rings) it seems like money well spent if you are lusting after a more functional, cleaner, lighter and more reliable set-up.
First ride was a quick loop around my local go-to trails, some brief pavement flats, technical, slippery single track climbing, buff double track climbing, packed snow and fast, rough, choppy single track descending. EArly on I realized that the B tension screw was a bit out of whack. Mis-adjustments with this are exacerbated on the smaller cogs. What this presented itself as was slight hesitation on the upshifts of the small end of the cassette. I stopped and easily adjusted the screw to move the guide pulley in as close as possible to the 42 tooth and the hesitation was eliminated. Basically—the ride was un-eventful from a drivetrain standpoint—this is a a very good thing. Not a single rattle, hesitation, mis-shift or dropped chain even with rough descending and no chain guide. The low–32-42 combination was just right as the absolute low gear, any lower and cadence is way too high for balance and cranking. There has been some reports of shifting suffering with removal of the 17T cog–this is total crap as it shifts perfectly sans-17 through the range. The 42 is a larger jump from a relative cog size from the next smaller one and there is no hesitation in picking up the chain.
All in all, this is a very good set-up and is recommended for drivetrain simplicity. Long term tests will reveal how shifting and chain retention performance changes as the drivetrain wears over its lifespan.