Bike Test: Cannondale Jekyll 4 Aluminum

The year 2012 marks the second year for the redesigned Cannondale Jekyll trailbike. This bike uses what Cannondale calls Enhanced Center Stiffness Torsion Control, or ECS-TC for short. We asked to test the lowest- priced version so that this everyman trailbike would be close to affordable for every man.

The Strange Case of Dr. Jekyll and Mr. Hyde depicts a person with split personalities?one mild-mannered and the other completely insane. This is exactly what the Cannondale Jekyll is all about. It’s part of Cannondale’s Over Mountain series, which offers bikes designed to give the rider a cross-country feeling?a short-travel bike on the way up and a long-travel mountain killer on the descent with the flip of a switch.

The Jekyll is available in carbon and aluminum versions, both with the same suspension setup, geometry and intended use. Our entry-level Jekyll 4 sports a full-aluminum build, which uses Cannondale’s CAAD aluminum technology to deliver huge, oversized tubes and flawlessly smooth welds.

The suspension, similar to that of the Scott Genius bike, uses a proprietary Fox pull-shock that works in reverse of most traditional compression-style shocks. The DYAD shock provides resistance as it is pulled apart instead of when it is compressed. The handlebar-mounted lever has two positions to adjust the rear-wheel travel between 3.5 inches and 5.9 inches on the fly. The frame also uses a 12×142-millimeter axle, a Press-Fit 30 bottom bracket, 1.5-inch head and steerer tube, and ISCG-05 tabs.

The ECS-TC system uses 15-millimeter thru-axles for the key pivots. Placing the axle bearings inboard and clamping the ends of the axle cause the axle to become a structural part of the link or swingarm. Cannondale feels that tying the two sides of the link or swingarm together via the axle dramatically increases the system’s ability to resist twisting loads.

Our favorite feature of the unconventional DYAD shock is its remote lever. The design allows the rider to switch the bike from short-travel mode to long-travel mode without removing a finger from the bar. The button that releas- es the switch is on the end of the lever, which makes it easy to hit with the outside of your hand rather than a 
thumb or index finger. Any feature that keeps the rider in control without forcing him to remove a hand from the bar is a welcome one. Since the rider will likely need the control when switching from short- to long-travel mode when rougher terrain is encountered, this design hits the nail on the head. Schwalbe Hans Dampf tires are an incredible spec. They are one of our favorite trail tires and will make nearly any rider happy. The tires deliver top-tier performance on a bike that’s designed to hit a price point.

Setting up the DYAD:
Cannondale provides a specially designed high-pressure pump with the 
Jekyll, and you’re going to need it. A 175- pound wrecking crewer found the ideal setting at about 370 psi in the positive chamber and about 320 psi in the negative chamber. That’s way more pressure than a standard shock pump is capable of producing. Next, we found that even small adjustments in pressure are immediately noticeable in the ride quality. This is not a system that allows you to get “close.” You need to be spot-on. Plan to spend some time tinkering before you find your ideal setting.The rebound setting must be set separately for both travel modes, and this involves two separate knobs. We set these near the middle of their adjustment range. Finally, be sure to follow the setup guide carefully, as pressurizing or depressurizing the chambers in the wrong order can move the internal pistons, and cause the shock to perform poorly.

Climbing: The DYAD shock delivers on its promise of a short- er-travel, more efficient bike when the lever is engaged. The best part is that it’s not a lockout. Whereas long-travel bikes feel like heavy hardtails if they have a full-lockout option, the Jekyll gives the rider just enough travel to gain traction on rougher terrain without a big compromise in efficiency. The Jekyll reacts well to either in- or out-of-the saddle climbing methods but feels best when the rider sits and grinds out the climbs.

Pedaling: The single-pivot suspension is remarkably well controlled with the DYAD shock, but can bob slightly under pedal- ing, even in the short-travel mode. Best results come from a smooth, steady cadence and staying in the saddle.

Descending: The Jekyll inspires confidence on rough terrain with a balanced rider position that tracks on high-speed descents and slow-speed technical terrain alike. The suspension has a very progressive feel that resists bottoming exceptionally well. As a result, the bike has a playful nature and loves to be smacked into rocks, roots and every obstacle on the trail. The first half of the travel is extremely active, delivering great small-bump compliance over chattery trails. The second half of the travel ramps up significantly to resist bottoming on bigger hits. While this bike doesn’t deliver a super- plush feel toward the end of the stroke, our setups delivered plenty of usable travel that begged the rider to seek out the fun lines on the trail.

This is our favorite feature of the Jekyll. The geometry is spot-on and gives the bike a fast feel in corners. The head angle is slack enough to inspire confidence that the bike will stay on track, even in high-speed sections where hitting your line is critical. The angle is also not so slack that the bike can’t make it through tight switchbacks? climbing or descending. The geometry feels balanced, natural and right at home on a 6-inch-travel trailbike.


The handlebar is too narrow and has a sharp backsweep that would feel more at home on a kid’s big wheeler than a high-performance bike. This is the first upgrade most riders will pursue. Thankfully, it’s a simple one. The front end feels relatively tall, which contributes to the playful nature, but can be a handful on steep climbs. Many riders will prefer to remove the headset spacers or flip the stem to the negative rise position to keep the front end from wandering. A lower rise bar could also help. This bike has a huge downtube that tends to catch every rock that gets kicked up from the front tire. During our testing, we didn’t experience any dents; however, we heard plenty of rocks hit the bottom of the tube. Paint chips or dents are only a matter of time if the terrain is rocky. A protector here would be a welcome addition.

The Jekyll is not a conventional bike, and with its proprietary features, you are locked into using the Fox DYAD. That aside, we love the playful nature that begs to be flicked down the trail. Riding the bike is a pleasure. If you can get over the proprietary nature of the Jekyll’s suspension system, want something a little different and want a great value at this price point, the Jekyll is the perfect option.

This test was reprinted from the June 2012 issue of MBA. Subscribe by clicking here.

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