Dirt Rag Magazine

Jamis Diablo Pro

Dual suspension, disk brakes, out of the box at 27.6 lbs. The Hayes hydraulic disks have slotted bosses for easy, no-drag setup.

By Karl Rosengarth

Setup: Dual suspension, disk brakes, out of the box at 27.6 lbs. The Hayes hydraulic disks have slotted bosses for easy, no-drag setup. I pumped the Fox Vanilla Float rear shock up to 160 psi to accommodate my 150 lbs. body weight and set the compression damping dial about 1/4 full (later, I learned that I read the Fox chart wrong, this was 20-50 psi less than recommended). I set the Manitou X-Vert’s preload, compression damping and rebound damping each to roughly mid-range.

Design: Jamis’ goal for the Diablo series was a neutral, active suspension bike with low weight, good lateral stiffness, high pedaling efficiency and good weight distribution. They created a no-holds-barred solution centered around their CentroSymmetric Pivot (CSP) rear suspension design (Say what???). Basically, it’s a rear swing arm that rotates around the bottom bracket, which is housed in the carbon fiber monocoque main frame. The CSP may look like a unified rear triangle (URT), but differs in that unweighting the saddle and weighting the pedals on the CSP does not weight the swingarm like it does on a URT. Also, with the chainstay pivoting around the bottom bracket, the chain length does not change as the rear suspension moves. It’s challenging to build a suspension that pivots around the bottom bracket-that’s one of the reasons for the carbon fiber main frame. The stiffness of the carbon fiber main frame is said to offer superior support for the bottom bracket and the pivot (my head is spinning, I wish my legs were).

Ride #1: After three straight January weeks of unrideable snow and ice, Crispy, Scotty and I tossed good judgement to the wind and went riding. Snow-free lawns buoyed our hopes as we headed into the woods, where we immediately encountered snow. No problemo on the initial downhill-the Hayes disk brakes were solid when wet, with plenty of "fee" right out of the box. Our luck ran out when we hit the deeper snow at the bottom of the shadowed valley. The Diablo felt like any other bike I’ve had to push through deep snow, hee, hee. Pedaling back roads the rest of the night, I noticed some rear suspension bobbing on the climbs (my bad, I hadn’t yet figured out that the rear shock wasn’t pumped high enough).

Ride #2: No more snow! Time to hit the park, early in the morning while the ground is still frozen. As I turned onto the Sam Adams Trail, I knew a pivotal moment was at hand. This twisted singletrack is full of tombstones (embedded rocks with sharp edges sticking up). I hit the gas, picking the most direct line, damning the tombstones-the Diablo held it’s line. The Manitou X-Vert up front delivered plushness (while clunking a bit), and the rear suspension held the drive wheel earthbound. Turn carving quickness was rather impressive for a dual boinger-the bike felt very stiff laterally and fairly snappy in the turns. Not as snappy as my rigid frame, but my rigid frame won’t allow me to stay seated and pedal through the rough spots like the Diablo did.

Ride #3: This would be my first "technica" ride on the Diablo. The trail we call "Perfectly Good” is full of humongous log hops. The Diablo proved to be a perfectly good woods bike-allowing me to clean most of the big logs. It felt effortless to wheelie the front wheel onto the leading edge of a big log, kiss off, push the bars forward and throw the rear wheel over. It felt like Jamis got the Diablo’s weight distribution spot-on (the radical V-shaped monocoque places the bikes center of gravity low and evenly distributed between the wheels, which works for me). Despite all my body english, the Time Atac pedals never blew out accidentally (wanna buy some used SPDs?).

Tech Support: The Jamis guy called me to see how things were going. I told him that I only had three rides, things were going well, except for a bit of bobbing in the rear end on hard climbs. I told him I normally rode a rigid frame, and he advised 210 psi rear pressure-just on the high side of the Fox chart (which I grossly mis-read initially). He also recommended increasing the rear shock damping (I went with 3/4 full). Also, I decided to firm up the Manitou to match the firmed-up rear-setting its spring preload and both damping controls to full hard.

Ride #4: Aaaaah yeah-the annual Valentine’s Day Massacre ride started out on the Plum Creek Trail. About half-way along, there’s this fallen tree measuring over two feet in diameter. I’ve never cleaned it on my own bike, but today I was over it like butter (smooth). Unsolicited comment from Bob, who was riding somewhere behind me: "You were the smoothest over that big log, man. Nice job.” What can I say, I guess I’m just a freak. On the first climb, I was relieved to find virtually no rear end bobbing (thanks to the correct rear shock pressure). Later, another unsolicited comment, this time from Mike: "I was watching your bike’s rear end and it was working real nice over that railroad ballast.” (insert Mike’s up and down hand motion here for dramatic emphasis).

Yeah, it felt real nice too, I thought to myself. That day I managed to clean every hill that anybody else cleaned (usually in second place behind a guy on what appeared to be a 19 pound Cannondale, who I smoked on the downhills). Out-of-the-saddle climbs felt amazingly like a rigid frame (that’s good). The ride covered 20 miles, which felt more like 40, with the power-sucking mud and occasional snow. Sure, I felt tired, but not hammered (thank you, Diablo dual suspension, thank you).

Ride #5: Scouted the March Hare Scramble race course (don’t ask, it’s an underground event). There are some rocky downs, over which the rear suspension kept the bike feeling very stable and in control. Front suspension felt a bit too stiff (mental note to back off the preload and damping). I’m starting to appreciate the nine speed drivetrain’s smaller jumps between rear cogs (after I sneaked in a ride on my personal 8-speed rig, then went back to the 9-speed).

Ride #6: Backed off the Manitou’s preload and both dampers two turns. Rode the March Hare Scramble course for pre-race trail maintenance. One minor problem was trying to portage a deep, fast-moving creek without a conventional diamond frame to shoulder. There’s no real convenient place to grab onto the Diablo. However, this ride sold me on the Diablo’s comfort. I had been sick and unable to ride for about three weeks (real nasty flu), and I expected to feel pretty whooped after 19 miles. But, both my back and my backside felt surprisingly fresh.

Ride #7: Same course as ride #6, but it was dry and fast. Feeling frisky enough to let ‘er rip on the steep downhill through the abandoned brick factory-imagine loose bricks, brick fragments, loose rocks and embedded staircase rocks. On the way down, I stayed glued to a couple of notoriously fast boys, which was evidence enough for me that I was really ripping and not just imagining. This was the first time I let the bike run wild through sketchy terrain, and the Diablo rewarded me with high speed stability and a cushy ride. Four inches of front and rear travel is sooo much faster than my rigid frame. That particular downhill run sold me on the 26” wide riser bars (Titec HellBent)-any problems with clearance in tight woods are balanced out by the improved steering control (not to mention better power transmission on the uphills).

Ride #8: I knew this was my final test ride, so I paid extra attention to any feedback from the Diablo. There wasn’t much (a good thing). Lack of feedback meant I’d reached the Zenlike "the bike disappeared beneath me” state of oneness with the Diablo. Come to think of it, I’d probably been in that state for the past few rides. The icing on the cake came late in the ride, on the steep climb out of Oil Well Valley, a section that has you on the verge of traction loss (and you have to fight to keep the front wheel from lifting). But, I rode it out clean (no dabs). Yes, the Diablo climbs well. Also worth mentioning: the Tioga Factory XC tires gripped like crazy under all sorts of ugly conditions. Finally: The Diablo rides like I want a suspension bike to ride-absorbing impact without robbing my pedaling energy or weighing a ton. When I finally buy a suspension bike, I want it to ride like the Diablo. The only scary part is the Diablo Pro’s suggested retail price of around $3,300. Scary, but fair, considering what you get-carbon fiber main frame, CSP rear suspension, hydraulic disk brakes, top-of-the line Manitou X-Vert fork, XTR rear, XT front /shifters, Time ATAC pedals and a Thompson seatpost. A lofty piece of engineering demands a lofty price. If you gotta have one, but have a tighter budget, you might want to check out the Diablo Comp at $2,500. From G. Joannou Cycle Company, 151 Ludlow Avenue, Northvale, NJ 07647; phone 210.768.9050.

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