Do you love single speed simplicity but you’re not willing to be left behind by your buddies? Wouldn’t you like to pick the gears you really use? Do you want a straight chain line for race performance? Then try this middle path approach for your drivetrain. Admittedly, I want too much. I am a weight weenie, speed endurance racer AND a very aggressive downhiller who aims for big air AND loves the big 29er wheels. For me it has to be light, fast and strong. If you’re in the know, then you already know about the added advantages of the big 29er wheel. However the traditional approach to the drivetrain with standard 3 rings 22-34-44 up front and 11-34 in the rear – is too many options and more complexity. When it came time for me to build my new bike what was I to do? Think outside the box – and this is what the Golden Bike Shop provided.Today I ride with a FSA K-Force Light ceramic BB crank in “non-granny gear” 2x9 mode with a 36 tooth Actiontec cog in the rear. It works amazingly better than anything I have ever used before. First I review the crank, then the rear cog.
FSA K-Force Light
In 2x9 mode, these rings are perfectly sized to keep the front derailleur shifting smooth: a 29 tooth for the small ring and a standard 44 tooth for the big. FSA uses a 3rd generation carbon process and a patented completely hollow arm design. All aluminum components (spindle and pedal insert) are laid directly into the carbon material as an integrated component (as opposed to bonding). Adding the ceramic bearings for the bottom bracket along with the completely carbon hollow arm design makes this crank smooth as silk! Seriously, have you ever flipped your bike upside down, removed the chain, and spun any type Shimano crank and seen it resist motion? Not this crank!
Positives
I have extensively tested this for well over a year including in big races, like the Colorado Trail Race.
Bottom line: no problems and spinning performance is top notch. It’s like a manual over an automatic transmission – solid and smooth.
Its carbon, so it’s very light.
Potential Negative
Rock garden descents happen. So does smashing the crank arms into rocks. Initially I was concerned that my pedal might fall off due to the carbon material. Yes, there is noticeable scuffing and nicks formed under my pedal inserts, but to my surprise no cracks or major damage. I can confirm with experience that these cranks are strong.
This setup works great but I wanted that extra bit of race pace climbing - Colorado style. I talked to Golden Bike Shop who calculated the “roll out” comparing a 29er with my setup and a 26er with standard gears. Without getting into the geometry, the short answer is I needed a 36 tooth rear ring.
Actiontec 36 tooth cog - Actiontec http://www.actiontec.us/ticog.htm builds titanium cog sets, with options from 11 – 39 teeth. Instead of a complete set, you can order a single cog and use it with Shimano or SRAM cassettes. A spacer is provided, so you simply remove one of the smaller cogs and add the large one. Note: this is not recommended by the manufacturer, but I can positively report success.
Golden Bike Shop did a great job as usual when they removed my XTR cassette and laid in the 36 tooth Actiontec cog. Being a single cog, it has no spider attached to it so it slides directly onto the hub (more on this later). Next, they added the included Actiontec spacer (in my case, for a nine speed cassette) and put back on the XTR 34 tooth cassette, with one modification – you have to select and then remove a gear (a 9 speed hub requires a 9 speed cassette). Since the majority of my riding is in climbing to midrange gears, I chose to remove the 13 tooth cog. To illustrate, a typical rear setup is like this: 11-13-15-17-20-23-26-30-34. Mine is 11-15-17-20-23-26-30-34-36.
Positives
My shifting has remained precise. At first I was concerned my derailleur wouldn’t be able to handle the added clearance of the 36 ring, but it works without any trouble. Although I use a rapid rise XTR derailleur (which I find superior, but that’s another story) others have reported success with standard derailleur.
Once in the ring, there is no possibility of slipping out as the teeth are “shark toothed”. The shift is precise – the chain cannot ride the top of the flats like most flat tooth designs.
It’s entirely titanium- super light.
It feels different once in gear. After all, I am shifting from XTR to Actiontec. This may be due to an increase in small lateral flex due to the Actiontec cog not being linked by a spider (unlike the XTR). This has not however impacted performance, and is thus not a negative. Besides, in this ring you’re moving slow. Further, this feeling has been useful by reminding me in case I accidentally shift into my big gear.
Potential Negative
Titanium on an aluminum hub. Like my DT Swiss 240’s, most hubs are made with aluminum. Titanium on aluminum has the potential to damage the hub, particularly since this cog is directly attached to it. For this reason I always “gingerly” shift into this ring (I don’t slam into this gear) and use it only when I “really need it”. I have inspected the hub several times and haven’t seen any wear and tear. Honestly, I think this will hold up for several years to come, but that is yet to be confirmed. Am I confident with it? Yes. I have read that other endurance riders have used this setup during the Colorado Trail Race and the Great Divide Race http://www.bikepacking.net/reviews/bike-components/actiontec-36-tooth-cog/
Overall, I am very satisfied with this setup and would recommend it to others!
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