CHUMBA RACING -CANE CREEK DOUBLE BARREL REAR SHOCK TUNING PROGRAM
November 1st, 2009
This whole project started because customers asked if the VF2 was capable of being more
than just an XC bike and if they could improve upon the RP23 that was fitted to the VF2. Awhile
back, Ted Tanouye, head of R&D at CHUMBA, and I were riding the Fullerton Loop in California.
After climbing a steep section of the trail, we stopped, and I asked, “How is that rear shock?” Ted
said “the VF2 with a CCDB could outperform an EVO equipped with an air shock.” For Ted – a
man who developed championship-winning race bikes out of his garage – to make such a claim,
gave cause for serious attention to this rear shock and how it would interact with CHUMBA frames,
specifically, our VF2 linkage system.
So I turned to one of the industry’s most knowledgeable shock gurus – Josh Coaplan,
head of R&D at Cane Creek. Josh helped develop the Double Barrel alongside other engineers at
Ohlin’s Racing, the premier shock manufacturer for off-road equipment, like ATVs, snowmobiles,
I sent Josh a VF2 frame for analysis of axle path and leverage ratio to help us optimize the
complex settings of the CCDB for the VF2. From my conversations with Josh and Malcolm at Cane
Creek – we hoped that this shock properly tuned to the VF2’s linkage would provide the basis in
which to help reduce pedal-induced bob while retaining the superior bump absorption and traction
that the CCDB is famed for. Coupled with the VF2’s linear linkage (more on that later) the CCDB
would offer unrivaled shock tune-ability and performance.
Upon receipt of the frame, Cane Creek proceeded to build their own hardware to make
sure a proper fit of the Double Barrel in the shock mount locations of the VF2.
After Cane Creek received the VF2, they proceeded to equip it with the proper hardware,
and started to do a full analysis of the leverage ratio, axle path, and other relevant data all from
real-world data acquisition.
The data Cane Creek acquired, matched all of the R&D testing that we had confirmed in
our 3-d modeling, as well are our prototypes, and actual production models.
We confirmed that the VF2 had an extremely linear suspension rate, almost like a minidownhill
bike. This means that the force required to compress the shock throughout the travel stays constant – meaning the bike feels consistent, predictable, and smooth throughout the whole
CHUMBA’s frames have the unique advantage of allowing the suspension to behave the
same way at all points of travel, allowing for smooth technical climbing, pedaling through rock
gardens with a fully active suspension, and descending with complete confidence and predictability,
whether riding on the trail, or hitting bigger drops and jumps.
CHUMBA and Cane Creek jointly analyzed shock settings and performance, testing the
CCDB on the VF2 with professional riders, engineers, and test riders both at CHUMBA and Cane
Creek. We then confirmed data between each other and found similar results.
Given the extremely linear nature of the VF2’s leverage ratio curve, the linkage will reflect
a shock’s tuning very closely. This means, if you tune up the low speed compression, you will
immediately feel this throughout the VF2 linkage’s travel without varying leverage rates from the
linkage interfering with what you want the shock to do.
This means if you own a VF2, or are interested in one, you have the advantage to really
custom tailor your Double Barrel to how you want it to perform at low speeds or high speeds, and
the linkage will remain neutral to accept your change, making the combination of the VF2 and the
Double Barrel one of the most customizable rides on the market.
If you are interested in more information on custom tuning with a VF2 or Double Barrel,
you can e-mail firstname.lastname@example.org or call 714-986-9100.
source: Alan Kany