Reviewing a proven winner is no easy task. In the hands of mild-mannered Jérôme Clémentz, the 160-millimeter-travel carbon-fiber Jekyll 27.5 has proven to be one of the most successful race bikes on the Enduro World Series. The SRAM-sponsored shredder races with a two-legged RockShox Pike fork, but enduro racers here in North America have had no problems racking up wins running the single-sided SuperMax Lefty that Cannondale specs on the bike, and what’s more, WTB/Cannondale sponsored Marco Osborne recently trounced all comers at the Mammoth Mountain US ProGRT national DH race on his SuperMax-equipped Jekyll 27.5 Carbon Team. Proven performances earned in the exact realms for which Cannondale’s designers intended the bike to excel makes it tough for a reviewer, armed only with riding impressions and objective criticism, to beat it down to size.
Different Can Be a Good Thing
Criticism is one thing that Cannondale’s most successful trailbike has had plenty of – and very little of it is bounded in the realities of handling and performance. Most detractors point at Cannondale’s extensive use of non-standard components as their source of ire. Forget the fact that its 160-millimeter-stroke single-sided “fork” is lighter than any of its two-legged competitors and stiffer than many DH forks: “It just looks wrong.” Overlook that Cannondale’s headset never needs adjustment: “I can’t adjust it!” Neglect to admonish that Cannondale perfected the 30-millimeter aluminum BB standard with oversized, pressed-in bearings years before major players considered the concept: “It doesn’t have threads.” Forget that the Dyad-RT2 pull-shock turns a supple long-travel suspension bike into a sharp-pedaling short-stroke climber with a flick of a lever: “I can’t bolt a coil shock on that.” And, of course there is that one-sided front hub that allows the rider to change a tube or a tire without removing the wheel from the bike: “So, now I have a wheel that won’t fit on my DH or dirt-jump bikes?” For the record, the Jekyll is not the bike for those who dream that all production bikes and their associated parts will someday be globally cross-compatible, so customers can creatively mix and match parts like a Lego mountain bike builder’s kit.
For the open minded, Cannondale’s Jekyll is one of the few truly integrated bicycle designs – a well-appointed, carbon-framed, 160-millimeter-travel technical trail shredder that delivers race-winning performance and handling. The Jekyll’s non-standard parts were developed by Cannondale to permanently resolve nagging problems related to performance, efficiency and reliability that contemporary bike and component makers were either patching up or ignoring entirely. For example: Rather than providing a compromise shock tune with a lockout or traction option, the Fox-made Dyad RT2 shock provides two separate shock systems, each with its own damping and spring rate – a 160 millimeter circuit, tuned for technical sections and descending and a 95-millimeter option with a stiffer spring rate and slower rebound for pedaling and climbing.
That said, Cannondale is not fixated upon using dedicated components merely for the sake of differentiating its products. Look beyond the Jekyll’s dedicated shock, “fork” and headset arrangement, and the remainder of its components are items that most would expect to find on a premier enduro racing bike: WTB i23 rims, DT Swiss hubs, Schwalbe Hans Dampf tires, a SRAM XX1 drivetrain, a RockShox Reverb Stealth dropper post, Magura MT-7 brakes and a Gravity 740-millimeter carbon handlebar and 50-millimeter aluminum stem combo. Built accordingly, the complete medium-sized Jekyll Team, at only 26.86 pounds(12.21kg) ready to rock, is lighter than most trailbikes with much less suspension travel. MSRP for the top-drawer Carbon Team reviewed here runs $7580 USD, with and sizes offered in small, medium. Large and X-large. More affordable models range from the $6170 Carbon 2, to a pair of aluminum-framed models: the $3900 Jekyll 3 and the $3250 Jekyll 4.
Jekyll 27.5 Carbon Team Details:
• Frame: Impact-resistant ballistic-type carbon construction, 160/90mm travel, single-pivot swingarm suspension, X-12 through-axle system, external cable routing, ISCG 03 tabs.
• Wheel diameter: 27.5-inch
• Fork: Lefty SuperMax, 160mm stroke, Carbon upper, aluminum lower, external rebound and lockout
• Shock: Dyad-2, Air-sprung, two chamber, remote-controlled pull-shock, 160mm or 95mm travel options with separate low-speed rebound controls. “Enduro” high-speed compression tune.
• Headset: Cannondale integrated 1.5-inch pressed-in type
• Bottom bracket: Cannondale BB30 press-in type
• Drivetrain: SRAM XX1 eleven-speed with Cannondale Hollowgram BB 30 aluminum crankset, 30-tooth XX1 chainring.
• Brakes: Magura MT6 with 180mm rotors (MT7 four-piston brakesare the current spec)
• Wheels: WTB i23 Team rims, DT Swiss 305 hubs, and DT Swiss Competition spokes.
• Seatpost: RockShox Reverb Stealth dropper post, 100mm stroke.
• Weight: (Medium size tested) 26.86 pounds (12.21kg)
• Sizes: Small, medium, large. X-large.
• MSRP: $7580 USD
• Contact: Cannondale USA
Cannondale says that it makes the Jekyll’s carbon chassis using a special high-modulus material that is used by armed forces where armor protection is necessary – which implies that it has a higher degree of impact resistance than more commonly used high-strength carbon. With two decades of carbon fiber bicycles under their belts, Cannondale’s designers are not afraid to profile the Jekyll’s frame tubes as narrow or as wide as required. Up front, the frame’s oversized head tube contains Cannondale’s tried-and-true press-fit 1.5-inch headset system which requires no periodic maintenance or adjustments. The massive top tube tapers quickly to meet the slender seat tube, while the downtube widens dramatically to 85 millimeters midway to the bottom bracket junction to support the suspension’s carbon fiber pull-shock rocker link. Elsewhere, the single-pivot swingarm and seatstays are crafted in semi-rectangular shapes to maximize stiffness and strength without taking up valuable real estate where drivetrain components and DH-width tires must pass.
Hollow, 15-millimeter-diameter axles are used throughout the Jekyll’s rear suspension and the sealed ball bearings are widely spaced to maximize lateral stiffness and minimize the effects of free play, however miniscule, that naturally occurs as all bearings wear over time. The axles are clamped to the outer segments of the suspension rocker link and swingarm to further secure the system against unwanted flex and also to simplify disassembly and maintenance.
At the rear of the bike, Cannondale designed massive, hollow carbon dropouts that house a pair of sealed ball bearings at each seatstay pivot, where clevis-type seatstay attachments further strengthen the pivot junctions. The aluminum derailleur hanger also attaches to the carbon dropout with a sturdy clevis mount. Cannondale employs the Syntace X-12 through-axle system which is secured with a six-millimeter Allen key. Threads on the drive side and a tapered collet on the left side lock the axle securely to the swingarm.
Practicality and ease of maintenance may have been the motivations for Cannondale, with one exception, to choose to route the Jekyll’s shift housings and brake hoses externally on the frame. Clean looking screw-in aluminum guides collect the two hoses and one housing that run to the bottom bracket on the underside of the downtube where a tough rubber frame guard does double-duty, also protecting the control conduits from injury. The remote hose for the bike’s RockShox reverb Stealth dropper post tucks into the seat tube though a rubber grommet. Oddly, even though there is an empty, fourth slot in the downtube guides, the remote cable that operates the Dyad-RT2 shock is internally routed through the downtube. The only explanation is that Cannondale’s design team were not committed to a one-by drivetrain and made the call to leave a spot for a future front derailleur housing.
Geometry tweaks to make the Jekyll 27.5 a more capable AM/enduro bike include a longer wheelbase and a slacker, 67-degree steering angle for high speed stability; slightly longer top tubes across the sizing range to compensate for its 50-millimeter stem, and a steeper seat tube angle to enhance climbing ergonomics. The offset of the Jekyll’s Lefty SuperMax has also been increased to 50 millimeters to match the bike’s steering geometry with its mid-sized, 27.5-inch wheels.
Detail oriented riders may appreciate that the simple profile of the Jekyll allows room inside the frame for a full-sized water bottle, and that the right chainstay has a large molded silencer/protector. Near the bottom bracket, a bonded stainless steel grind-guard prevents a derailed chain from destroying the carbon swingarm. Strangely, Cannondale chose the earlier, ISCG-03 mounting pattern for its dedicated chainguide tabs – but it’s there, nonetheless, for those who want the added security. Finally, if you absolutely need a front derailleur, Cannondale sells a direct-mount adaptor that fits threaded mounts on the right swingarm pivot – a handy item for any racer with a drivetrain sponsor that is keen on front mechs.
Dyad RT2 Pull-Shock
Cannondale worked out a new, high-flow compression circuit and tuned the Jekyll’s Dyad RT2 shock to work especially well on fast, technical descents that are typical of European enduro courses. As previously mentioned, in lieu of a lockout or a low-speed compression boosting circuit like Fox and RockShox use, the Dyad’s remote handlebar lever can switch the pull-shock between two fully functional 90-millimeter or 160-millmeter-travel modes.
Those who want to check out the inner workings of Cannondale’s Dyad RT2 pull shock should check out Matt Wragg's Q&A on the subject. The short version is that the Dyad offers two separate damping and spring-rate functions in one shock mechanism. The pull-shock arrangement is not necessary to make the Dyad function properly, but it simplifies the suspension’s mechanical design and the shock benefits greatly by having all but one of its seals continuously lubricated. Dyad shocks have three chambers: the central pull-shock is basically a pump. When the suspension pulls on the pump shaft, depending upon where the remote lever is located, the pump forces shock fluid into one or both of the adjoining chambers. Each of the side chambers has an internal floating piston (IFP) and the air space that the floating pistons create functions as the shock’s air spring. In the long-travel mode, the pump fills both chambers and because the combined volume of the air springs is at its maximum, the Dyad shock’s spring rate is very linear. In short-travel mode, one chamber is closed off, which causes the pump to push a larger volume of fluid into a smaller air space. The combined effects create firmer damping, a sharply rising spring rate, and about a 50-percent reduction in the shock’s travel. Separate low-speed rebound circuits allow riders to fine-tune their rear suspensions for both short and long-travel modes. Small-bump sensitivity is tuned by adjusting the pressure of the Dyad’s negative air spring – an IFP located in the lower section of the pump.
While deciphering the Dyad’s workings can make many readers dizzy, the damping controls are all the same bits that one finds in conventional shocks Fox Racing Shox partnered with Cannondale to engineer the Dyad RT2 and it has proven to be a reliable system. Cannondale also has done diligence by opening authorized service centers that can maintain and tune them. Two important Dyad RT2 facts that prospective Jekyll owners should know is that it should be run with at least 30-percent sag in the longer-stroke position and that you’ll need to bring the special high-pressure shock pump that Cannondale provides if you want to do trailside adjustments. Dyad shock’s normal pressures begin at 300psi (about 20.7 bar), which is the top of the red zone for a standard shock pump.
Three Things to Know About the Lefty SuperMax
How it manages to be torsionally rigid: The Lefty’s inverted tubular stanchion tube is necessary to provide a sealing surface. Inside, the stanchion is rectangular and instead of sliding on bushings, it rolls on four rows of needle bearings trapped between the stanchion and matching tracks in the Lefty’s carbon fiber upper. Unlike sliding surfaces like conventional fork bushings, the Lefty’s needle bearings roll freely with minimal lubrication. Additionally, its four-sided tracks arrest torsional flex far more effectively than the wimpy arches and oversized axles that are used to prop up the stiffness of conventional forks.
Conventional damper: Inside the Lefty is a pretty conventional damping cartridge, similar to what you may find in many 160-millimeter forks. The 2015 SuperMax on our test bike has a new high-flow compression piston and both its compression and rebound valve stacks are tuned for higher speeds and proper descending. Two-legged forks typically use one side for hydraulics and the other for the air spring. The Lefty, however, splits the real estate inside the strut, with the damping cartridge occupying the upper section and the air spring housed in the lower, stanchion end. The damping cartridge requires only one special tool and is easily removed from the top for tuning or service.
Removing the wheel: The Lefty’s aluminum front axle is tapered, so it requires a matching hub. Many top wheel makers offer Lefty-compatible front wheels and hubs so Jekyll owners need not be concerned about future upgrades. There is no need to remove the wheel to change tires or fix a flat, but when you do have to remove the Lefty wheel, you’ll first need to unscrew the two fine-threaded 8mm screws that fix the brake caliper to the Lefty’s stanchion about two revolutions. The caliper mount will then lift off the screws and the brake rotor, which will in turn, allow the hub to move off of the axle. Unscrew the hub from the end of the axle with a five-millimeter Allen key and be sure to keep the hub and the exposed axle squeaky clean, because the bearings will be exposed and their inner races are a precision fit over the axle. After you reinstall the front wheel, replace the caliper mount. As long as you didn’t squeeze the front brake lever, the counter-sunk heads of the caliper retention screws should re-center the brake pads where you left them.
Those unaccustomed to riding a mountain bike with half a fork should probably throw on some lights and make their first outing on the Jekyll at night. Both of the riders who participated in this review admitted that it took three or more rides to stop looking down at the Lefty SuperMax and imagining that it was acting in ways that in reality, it doesn’t or simply can’t do. In truth, the Jekyll’s front suspension requires a break-in period before its needle bearings start to run freely and its low-speed damping falls into step with its two-legged competitors – about seven hours, says Cannondale, before the Lefty really starts to impress. Seven hours of riding is well beyond the scope of a parking lot test, so prospective clients may be put off by the initial harshness of the one-sided strut if they throw a leg over a fresh one for a first ride. True to their statement, though, the Lefty smoothed out considerably after the first few rides and we found that we needed to increase the air-spring pressure five to ten psi to compensate for the new-found suppleness.
Dialing in the Suspension: Setting up the Jekyll’s Dyad RT2 shock was made easier by the printed guide that was pasted to the frame, and also by the fixed sag gauge on the side of the pull-shock chamber. Because a pull shock relaxes in the completely retracted position, an O-ring on the shock shaft is not an option.
Beginning with Cannondale’s rider weight/shock pressure guidelines (320psi for the positive spring and 280psi for the negative side), the sag gauge measured 30 percent. At that setting, the Jekyll’s rear ride height felt a touch tall on steep descents unless the Lefty’s spring pressure was set higher than necessary. Dropping the spring pressure to get the shock to sag at least to the 35-percent mark and running the Lefty’s sag a little higher at 25-percent achieved a good balance for descending and technical trail work. Lesson learned during suspension setups was to be mindful of the negative spring pressure. Too low and the Dyad’s rebound circuit gets overwhelmed and the Jekyll will bounce when it lands a jump or bangs through square-edged hits. We learned to err on the high side of the negative spring chart and to set the long-travel side of the Jekyll’s suspension downhill soft – because we quickly discovered that we could rely on the super firm, short-travel mode for any substantial stretch of pedaling.
Climbing and acceleration: With a suspension tune that was admittedly biased for the downs, it should come as no surprise that the Jekyll felt a bit sluggish when climbing until the shock was switched to short-travel mode. At this moment, the tail of the Jekyll rises slightly, the bike’s geometry feels a tiny bit steeper, the rear suspension wakes up and the bike accelerates with more ease and a snappier feel at the pedals. The difference is not subtle. Some designs in the Enduro/All-mountain category, like the Pivot Mach 6 or Intense Tracer 275c, feel reasonably efficient while climbing or sprinting with the pedaling aids switched off. The Jekyll is not among them. It will accelerate and climb in the 160-millimeter mode if called upon, but beyond short stints to top rough climbs or to gap a jump, most riders will be reaching for the remote lever. That said, the lever is both easy and intuitive to operate – push the thumb-lever forward for climbing and simply tap the button at the end of the lever with any part of the hand to release it to full-travel mode. Cannondale designed the lever so it can be reversed and used on either side of the handlebar.
Technical skills: The Jekyll’s lateral and torsional rigidity up front makes short work of boulder drops and dicey descents where line choices are measured in inches. That said, there is enough handling in reserve to cover a multitude of sins should you blow your line and have to bounce and skid to safety. Cannondale’s choice of tires was a good one, with the 2.3-inch Schwalbe Hans Dampf knobbies able to find grip on a variety of surfaces, from dust to slick rock. Braking and climbing traction were definitely enhanced by the tires, but much of the credit is due to the Jekyll’s roomy feeling front center, which allowed test riders to keep pressure on the front tire while descending steeps and also to weight the rear wheel while climbing technical stints without the need for excessive fore and aft body movements. The Jekyll feels long and with the medium sized bike’s wheelbase at 46.4 inches (118cm), it is, so it feels much more balanced at speed than it does poking around at a tourist pace in the rough.
Cornering: With a tallish, 14.3-inch bottom bracket, one would imagine that the Jekyll would be less than smooth around the bends, but its length and weight-balance may override that aspect. Once riders learned to trust the Jekyll at speed and push it into the turns, our apprehensions melted. The Jekyll rider can push the front or slide the back tire with a degree of confidence, without dropping a foot – although I must admit to a few low-sides due to overconfidence and not dropping my foot. The downside was that in two months we nearly ripped all the edging blocks off both tires – which says a bit for the bike. To reach those sweet blocks of tacky rubber, we had to lean the bike pretty far over, because the narrow, WTB i23 Team rims further rounded out the profile of the already round Schwalbe tread pattern. Note to Cannondale: “Please spec wider rims, maybe the i25s, and add a rear tire with sturdier edging blocks like the Rock Razor.”
Descending: Part of the reason for the untimely demise of the Hans Dampfs may have been the hours spent riding the local DH trails. Riding what is essentially a 160-millimeter, mini DH bike that weighs under 27 pounds and climbs with relative ease means that is possible to double the number of downhill trails that can normally be ridden in an afternoon session on a big bike, so the Jekyll got a lot of extra credit laps on trails that pushed it close to the edges of its design envelope. Pushing the Cannondale hard into rock gardens and skipping down stepped drops showcased the Lefty SuperMax's big-hit smoothness and steering precision. Riding at full volume plays well to the Jekyll's long wheelbase and DH rear-suspension tune. With the rider more or less centered between the wheels and a "fork" that stays up in its travel, the bike feels calm and controllable down the steeps. Turns out that the Jekyll also jumps pretty well and its suspension can shake off some pretty hard landings too.
Riding DH trails also highlighted the fact that the Jekyll was under braked for its capabilities. Our test bike was equipped with Magura’s lightweight MT6 brakes, which feature two-piston calipers and are normally used on lighter weight XC/trail machines. Cannondale indicates in its published specifications, that the Jekyll Carbon Team should have had Magura’s much more powerful MT7 brakes with four-piston calipers, which would have been the better choice. A phone call to Cannondale revealed that in fact, Magura did not have the MT7 brakes when our first-production test bike was built, so the MT6 brakes were substituted. All subsequent Jekyll Team Carbon models have the more powerful four-piston calipers and upgraded levers.
Oddly, the MT6 brakes may have assisted us in keeping the Jekyll’s rear wheel in control down the steeps. Like most single-pivot-swingarm suspensions, the Cannondale’s tail end tends to stiffen up under braking. The softer bite and ease of modulation of the Magura’s MT6 brakes helped us to keep both wheels rolling and in control. We never ran short of power stopping the bike with the Magura MT6 brakes, but we had to use two fingers and squeeze harder than we wanted.
Reverb Stealth dropper post: Good – still the one all dropper are measured by. Bad – only 100 millimeters of travel is not enough for a bike that descends as well as this one.
WTB i23 Team rims: Good – tubeless aired up with a floor pump, still running straight and well-tensioned. Bad – i23 is the new width for cross-country, not all-mountain.
Dyad RT2 shock: Good – full-time rear suspension, exactly what I want, exactly when I want it.
Magura MT6 brakes: Good - Lighter than stink, good modulation on slippery terrain. Bad – lack of power and the direct-mount perch for SRAM shift lever needs more angular adjustment range to get the levers closer to the thumb. Note: Cannondale sent us a set of MT7s, and we will report back later.
Lefty SuperMax strut: Good - Best Lefty ever, not as good as a RockShox Pike is for damping quality, but it kicks ass at speed, especially in the steering department. We could be happy with it.
Cockpit: Good - Comfortable WTB saddle, just-right 740mm handlebar width, and we liked the 50mm Gravity Light stem. Bad - Cannondale's lock-on grips spun on carbon bars.
Hollowgram BB30 crankset: Good – Competitive weight with carbon cranks and it can be trusted to take a beating, outfitted with SRAM XXI 30t chainring.
Hans Dampf tires: Good - One of the best all-purpose technical trail tires. Bad - Jekyll needs a better edging tire on the rear.
The Jekyll Carbon Team is the package deal that most would consider to be a competitive enduro racing bike. Look no further than Cannondale's Overmountain enduro team to find proof. It is lightweight enough to challenge any superbike with similar travel and its dual-range rear suspension lets the rider decide when energy conservation takes precedence over traction and control. Its single-pivot-swingarm suspension, while not sophisticated, is rugged and simple, with performance that is tough to beat on the downs where it matters most. On paper, the bottom bracket is too tall and its steering angle is too steep, but the Jekyll burns up corners and inspires confidence when smashing technical trails. Its chassis is long enough to hold a line at speed and while the Jekyll's stability may take away a measure of its singletrack appeal, most enduro racers or all-mountain shredders would happily sacrifice some low-speed nimbleness for the extra shot of confidence that the Cannondale offers up on the opposite end of the spectrum.
The Jekyll's downsides are not deal breakers either. Its suspension takes a while to achieve the correct balance before the bike can deliver the full measure of performance it is capable of. Its skinny rims are outdated in the realm of AM/enduro and, if the Magura MT6 stoppers are the correct spec, it is a under-gunned in the brake department. That said, step back a couple of paces, view the Jekyll Carbon Team as an entire package and the truth is that, without changing a thing, it has everything a good rider needs to crush some stages at the local enduro races, or knock out some infamous lines on the home trails. What the Jekyll can't do is answer all the questions you are sure to get about its unusual looks. That is, unless you let the trail do the talking. - RC