Just In – Wolf Tooth Components GC 42T Cassette Adapter

by Brian Mullin on February 16, 2014

The marketplace
for the ultra-large cogs for 10-speed systems is getting pretty hot,
and OneUp Components 42T cog is now joined by Wolf Tooth Components GC
42T, and soon by the UK’s Absolute Black 40T, making for a much wider
selection of vendors for this interesting and functional product.

1×11 system (XX1/X01) has many exceptional characteristics, including
simplicity, functionality and smoothness, but the price tag and the
requirement of mostly using a full set of SRAM parts for the drivetrain
has kept many people away from enjoying the benefits of the product. It
didn’t take long for third party companies to jump into the fray to give
consumers workarounds for the 1×11 system, so we now have cassette
adapters from Wolf Tooth Components and OneUp Components that use
portions of a 10-speed 11-36T along with an additional large cog to give
a wider gearing range to more closely emulate the SRAM 11-speed 10-42T

The Wolf Components GC 42T cog comes in either a
Shimano and SRAM specific model, and fits Shimano XT and XTR, and SRAM
X5, X7 and X9 11-36T cassettes, and you remove the inner 17-tooth to
keep it as a 10-speed system. Another interesting aspect of this system
is that you can run it as a 2×10 if desired, though I am not sure what
front gearing you might use. The GC 42T cog is made from aluminum,
weighs 85 grams, retails for $89.95, and comes with a longer (25mm)
steel “B-screw” with a hex head. The cog has six special ramp section
around the circumference to aid in shifting, and to keep the cog from
digging into the soft material of most freehub bodies it has wide tabs
by the spline for better load distribution.

My initial test setup
on my Ibis Ripley 29er is an XTR 11-36 cassette, a medium caged X0 Type 2
rear derailleur and an E*thirteen TRS+ crankset with a 32T chainring
(original 2×10 was 24-34T).


pulled the XTR cassette off the rear hub and tossed out the 17 cog and
its accompanying spacer. I added the GC 42T cog to the hub, and then the
rest of the XTR stack (minus the 17t), and cranked it down to specs. I
liked that the GC cog had a small dot pointing at the notch, so it made
it easy to line everything up on the free hub body. Swapping everything
out increased the XTR cassettes weight by 65 grams (85g for the 42T cog –
20g for the 17t/spacer), which should be about the same weight
difference (give or take) for any of the appropriate models since the
17t is usually made from stamped steel. When I converted from the 2×10 setup, I removed the front derailleur, front shifter, inner 24t
chainring, added the 10-42T cassette and replaced the E*thirteen 34t chainring with a Pacenti
32t, for a total weight saving of 290 grams (.64 lbs.).

Note: I located an old
Shimano 16t cog in my parts bin, so I swapped out the 15t with the 16t
to create a more even range in gearing: 11-13-16-19-21-24-28-32-36-42.
The difference in shifting using the 16t vs 15t isn’t really that
significant, but does make for slightly smoother transitions.

I wasn’t sure how long of a chain I might need for the 42-tooth rear and
32-tooth front combination, so I bought a new 120 link SRAM PC 1071
chain, and ended using 112 links plus the PowerLock connector. As shown
above, that chain length worked fine for both the highest and lowest
gearing options.

I replaced the standard B-tension screw with the
kit’s steel 4x25mm hex bolt, since it gave me additional length if
required, and the toughness of a non-alloy bolt and the functionality of
a hex head. I had to play with the B-tension until it shifted smoothly
between the 36T and 42T cogs, else it would shudder, and I ended up
getting it close to its limit to keep the pulley the proper distance
from the cog. I also found it was best to alter the B-tension screw when
it wasn’t under pressure, so downshift to the middle of the cog when
making major changes. According to Wolf, if you’re using a Shimano
derailleur, you might need to reverse the B-tension screw to gain
additional length.

First Impressions

how does it ride and shift? It works surprisingly well, and in direct
comparison to the 32T to 36T up shift, there is a slight loss of
smoothness, and a bit more of a thunk during the 19T to 15T drop due to
the missing 17T (same goes for 19T to 16T in my secondary test);
otherwise, I didn’t notice any outstanding issues. I have taken it out
for several days of riding, and it shifted flawlessly, in fact; I would
be hard-pressed to realize that I had this gearing installed on the
bike. I cranked things under heavy loads on some pretty steep terrain,
in both loose and smooth conditions, and the shifting and power transfer
worked fine. We had some adverse weather conditions, so it got some
snow and mud tossed into the system during shifting, and continued to
perform admirably. I certainly liked not having to roll up and down
through the front derailleur to get my desired gearing options, and I
felt as though I could spin better with the larger chainring compared to
a granny sizing.

How does the shifting compare to the OneUp 42T
cog? It shifts with slightly more precision and crispness than the
OneUp, and although that’s noticeable, it isn’t that significant in the
grand scheme of things. I am not sure if it’s the way Wolf has done the
individual teeth design or their 6 ramped sections, but whatever they
have done makes a subtle difference. Wolf found that the timing of the
shifting ramps is extremely critical and SRAM and Shimano are very
different, so they designed Shimano or SRAM specific versions to offer
the best possible shifting performance. The OneUp cog can be used with
either vendor by moving some included spacers to specific locations.

does it compare to SRAM 1×11? The overall shifting isn’t on par with
the smoothness of the 11-speed design system, but it does more than a
decent job, and I never had any real issues with it. Obviously, the
10-speed rear derailleurs are optimized for a 36-tooth maximum, and
weren’t designed to be used 42T, but they work surprisingly well,
although the smaller cog shifts are slightly clunkier due to the
B-tension setting.

Final Thoughts

I had the derailleur tuned properly and chain at the correct length,
the GC 42T system has worked exceptional well, and I really didn’t
notice any difference in usage compared to my original 2×10 normal setup
(11-36T rear and 24×34 front). I think this simple system, with its
low-cost and fewer part swap outs will appeal to a lot of people. The
$89.95 price, and maybe a new chain, clutch derailleur and a narrow-wide
chainring will get you a pseudo alternative to the SRAM 1×11 wide range
of gearing. The Wolf Tooth Components GC 42T cassette adapter is a
well-made product, and their subtle ramping design makes for more
precise and smoother shifting, and makes any 1×10 and 2×10 have a much
wider range of gearing, allowing to compete against SRAM mighty 1×11
system for a fraction of the price.

  • Wide range 1×10 gearing
  • 1x and 2x usage
  • Low-cost and fewer part swap outs compared to SRAM 1×11
  • Kit comes with a longer steel B-tension screw with a hex head
  • $10 less expensive than the OneUp Components 42T cog
  • Subtlety smoother shifting than OneUp
  • Missing 10T cog of SRAM 1×11 cassette
  • Clunky 19T to 15T shifting (due to missing 17T)
  • General clunkier smaller cog shifting due to B-tension setting
  • SRAM or Shimano specific cogs – OneUp Components 42T cog does both
  • Price: $89.95
  • Weight: 89 grams
  • Size: 42 tooth only
  • Gearing: 11-13-15-19-21-24-28-32-36-42

For more information visit: www.wolftoothcycling.com.

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