2012 Jamis Dakar SixFifty B Pro Long-Term Review: Part I

Test riding mountain bikes at an expo is a lot like sampling teriyaki chicken at the mall: it all tastes good, but you can’t really tell which is the best until you’ve eaten a full serving.

After demoing the 2012 Jamis Dakar SixFifty B Pro at the Southeast Bike Expo in February, I knew that I had to have a full-size helping of this delicious meal. Jamis was stoked to get one of their rigs into my hands for review, and shipped me one as soon as the container full of bikes arrived from the Far East.

Specs

The frame is made of a “Kinesium alloy” and features a 69-degree tapered headtube (more geometry specs available here). While at first I thought the term “Kinesium” was just a creative way to market an aluminum frame at a high price point, according to Sal, Jamis’s product manager, it is anything but:

Kinesium was developed by Kinesis engineers to raise the standard and lower the weight of bicycle frames. Twenty-five percent stronger than traditional 7005 series aluminum, Kinesium allows us to build frames using thinner butted tubing with no compromise to frame strength.

The frame sports an mp4 suspension linkage with a RockShox Monarch RT3 (130 mm of travel), 10 mm hardware, and cartridge bearings in all the pivots. Moving farther back, the rear end sports 12 x 135 mm thru-axle dropouts with a stock Maxle Lite rear axle and asymmetrical chain stays to provide superb rear-end stiffness. No detail has been left out on this frame, with routing for a dropper post already in place along with tabs for a chain guide.

Up front, a White Brothers Loop TCR 650B fork with 15mm thru axle, 32mm stanchions, and a tapered alloy steerer control suspension duties with 130 mm of travel. Wheels are American Classic 650b XC Disc (hubs and rims), and they hold Kenda Nevegal 650b tires (2.35″ front and 2.1″ rear).

The brakes are a very respectable SRAM X0, with an almost completely blinged-out 2×10 X0 drivetrain (besides the X9 front derailleur).

I’ve spent a significant amount of time on 2×10 SRAM X7 and X9, and Shimano 3×9 XT over the past couple of years, and I was seriously impressed by the performance of the 2×10 X0 drivetrain. At first I thought the increase in performance would be slightly better than the X9 drivetrain (along with a little less weight), but I’m now firmly of the opinion that X0 shifts significantly smoother and is much, much more durable! For more information on SRAM’s X0 2×10 drivetrain, check out Jeff’s detailed two-part review: Part I, Part II.

A WTB volt saddle will hold your weight and take care of your sensitive parts, and a Ritchey Pro Rizer with a 20 mm rise, 670 mm width, and Jamis lock-on grips on the end complete the stock contact points.

Out on the Trail

It didn’t take me long to get acquainted with the geometry of this mountain bike: this is one of those rigs that feels like you’ve ridden it for years. Once I got the suspension adjusted properly and made good use of the dropper post routing by swapping out the stock post for a dropper, I was ready to rip!

I have put over 700 miles onto this mountain bike in the short three month time period that I’ve had it. I’ve ridden this bike on all kinds of trails in six different states, ranging from fast and flowy to tight and twisty to so gnarly I should have been running a dual-crown fork.

This bike was my go-to rig during my epic summer road trip. Some of the gnarliest trails I’ve ridden it on include, but are not limited to:

If any bike I’ve ever reviewed has received a true punishment, this would be the one!

The Dakar SixFiftyB lands squarely in the “trail” category, but the edges around the category got downright hazy when I actually got the bike into some gnarly terrain. While many of the details, such as the dropper post routing, chain guide tabs, the big knobbies, and 5.5″ of suspension allowed me to shred this bike like an all-mountain rig, the other details give it more of a cross-country feel. The rather steep 69 degree headtube angle (for a bike with 5.5″ of suspension), long stem, bars that I wish had been wider, a fixed-position stock seatpost, and the XC American Classic wheels limit the utter gnar factor.

None of these things are good or bad–they’re just the character of the bike. In fact, the American Classic XC wheels performed remarkably! I ended up putting big dents in both rims and breaking a spoke, but after the second rim dent I thought to myself, “what’s up with these wheels?” That was the first time that I realized these were XC wheels: not trail or AM wheels, XC. I pushed these wheels hard on extended rock gardens, drops, and brutal G-outs on trails such as the infamous Porcupine Rim and Downieville Downhill. Heck, I even tried to keep up with guys on full-blown DH rigs with massive dual-crown forks and DH wheels while shredding at Snow Summit!


In short, I pushed these wheels way past their intended use, and they still came through the fire in one piece. Despite the two dents in the rims, these wheels still track very straight, and I’m still riding them hard. Smart choice, Jamis.

Click here to read Part 2 of this long-term review.

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