• Bionicon Golden Willow Scandium
• £2,550
• www.bionicon.com
• Push-button attitude adjustment
• Lightweight Scandium frame

Vital statistics

All dimensions based on 18in frame

Germany’s Bionicon has been pushing its unique adjustable-geometry mountain bikes for a few years now. The full lineup of bikes featuring the UpNDown system includes a bunch of long-travel freeride/DHish bikes with enhanced going-up capabilities and single-pivot back ends, but the Golden Willow Scandium that we’re looking at here stands slightly apart. It’s pitched more at the XC/enduro set and features a proper four-bar back end while still taking advantage of Bionicon’s innovative air-assisted travel and geometry adjust system.

Frame

In most ways, the Golden Willow frame is a fairly conventional four-bar 120mm travel chassis. The Scandium front triangle saves 300g over the regular Golden Willow frame, with a claimed frame weight of 2.5kg (5.5lb). The front end is all conventional straight tubing, with an array of gussets and the front. There’s an hour glassed headtube, and another pair of gussets help to support the extended seat tube.

At the back, a pair of swoopy rocker links connect the shock to the sqaure-section four-bar back end. Chainstays are asymmetric, with the right-hand one swooping down out of the way of the front mech and chainrings. Holding the back end up is an X-Fusion rear shock. This looks entirely conventional at the top, but at the bottom are Bionicon’s unique extras. There’s an additional air chamber at the bottom, with a second valve and an air hose that disappears through a hole in the down tube and reappears up near the head tube before connecting to the big adjustment button and the front fork.

Usually we just discuss the frame itself here, but such is the level of integration on the Golden Willow that we’ll discuss the Double Agent fork too. It’s an adjustable travel, 70-150mm air fork, with a pair of shallow aluminium crowns allowing space inside to accommodate such a big travel range without an unduly tall fork. The crowns offset the legs well forwards to maximise the available steering lock. We were mildly surprised to see regular QR dropouts at the bottom end – yes, this is an XC/enduro bike, but when you’ve got this much travel available up front we value the extra stiffness and security of a through-axle setup.

Uniquely, the fork is pressurised via the valve on the secondary air chamber on the shock – you need to turn a valve at the top of the fork leg to make sure that the air ends up in the right place. The rear shock is set up as normal. It’s the connection between the secondary air chamber on the shock and the fork that makes Bionicon’s adjustment system possible. Pressing the bar-mounted button and compressing the fork feeds air from the main fork chamber to the bottom of the shock. The fork gets shorter, the shock gets longer. But that air is separate from the air that actually suspends the back of the bike – you get 120mm of travel from the back end all the time, it’s just the eye-to-eye length of the shock that varies.

To go the other way, press the button and compress the rear and the rear shock will shorten, with air from the secondary chamber being forced back into the fork, which extends. From one extreme to the other you’ll get a difference of about 6° in head and seat angles and 80mm in fork travel, but without affecting rear travel or bottom bracket height.

Components

The test bike was something of a demo mongrel with a couple of parts not as per spec. None of the differences had much impact on the ride, though. In fact, the stock spec is quite eclectic. The transmission is mainly from SRAM, with X9 shifters and rear mech and a PG980 11-34 cassette. Cranks are Truvativ Stylo Team, while, Shimano gets a look-in with the XT front mech.

Formula’s K24 brakes aren’t often seen as original equipment, which is something of a shame as they certainly do the job. The Golden Willow packs 180mm rotors at both ends. Wheels comprise Bionicon-branded DT hubs, Alex rims and DT Swiss Competition spokes, shod with Schwalbe Racing Ralph 2.25in tyres.

Finishing kit includes Bionicon’s own seatpost, notable only for being a fairly unusual 30.0mm size. More interesting is the Twin-Lock stem, which is integrated into the upper crown of the Double Agent fork and offers a substantial degree of adjustment. The twin bar clamps can be rotated through 135 degrees, or the whole thing can be bolted on to one of two mounting positions 10mm apart to tune the reach.

Given the twin-crown fork and all the extra bits required to make the travel and angle adjustment system work, we were pleasantly surprised that the Golden Willow came in at 12.6kg (27.5lb) complete. Also pleasantly reassuring is the price – £2,550 clearly isn’t cheap, but the Bionicon compares favourably with other bikes in the price range. It’s similar money to a Gary Fisher Roscoe 2 or Specialized Enduro Expert, for example. And if it’s a little spendy, there are three cheaper models with the slightly heavier all-aluminium frame – Golden Willow entry level is the £1,920 Golden Willow II.

Ride

With everything set up (a surprisingly straightforward process – there’s just an extra bit of button-pushing and valve-twiddling over a convention FS bike) and Bionicon’s magic interconnectedness in a middling, neutral position, the Golden Willow rides in a reassuringly bike-like fashion. The dual-crown Double Agent fork might contact the frame on really slow, tight bits (or crashes), but that’s about the only difference you’ll immediately detect. The suspension works, the geometry feels conventional and everything is poised and balanced. But if the trail steepens in either direction, a squeeze of the big orange button and some weight shifts bring all sorts of new things to the party.

Many riders will be accustomed to the idea of adjusting fork travel on the fly – most of the major fork makers have some kind of lock-down feature available. Shortening the fork and steepening the head angle certainly helps with weight distribution and reduced wandering on climbs, but there are downsides. If it’s only the fork that changes length, the BB height drops too, with potential for pedal strikes on rocky ground. Which doesn’t help you to maintain a steady rhythm.

Bionicon’s system has no such problems. As the fork shortens, the rear shock gets longer. That means that you get more variation in angles but at the same time the BB height stays up. At full steepness on a suitable climb, the Golden Willow feels like a funicular railway – you’re sitting fairly level despite the slopiness of the ground. It’s very effective on steep pitches, and you can take full advantage of the rear suspension with no clearance worries. At its shortest, the fork delivers 70mm of travel, which is plenty on the kind of climbs that demand the extremes of the adjustment.

Heading back the other way, the real fun starts. The system’s pretty easy to use when you get used to it – to get into full slackness, push the button, weight the rear and release. We found that the easiest way was to use a motion a bit like doing a manual, only less so. You end up with 120mm of travel at the back, 150mm at the front, angles not far off a DH bike but still with a sensible BB height, and it’s a lot of fun. The air-damped fork can get a bit overfaced if you’re heavy or aggressive (which is a polite way of saying “clumsy”), but we’d try it as stock first and then fit the optional rebound cartridge if you find you need it.

No complaints with the back end, although you’ll start to detect a bit of flex under the borderline hooliganism that the big fork/full slackness setting tends to encourage. That’s not really a criticism – this is a pretty light frame, and it’s nothing terrifying. Just think of it as a signal that you might want to think about backing off a bit.

Bionicon’s travel/geometry adjust system works, and works well. We’re not sold on the idea of 150mm travel twin-crown forks with QR dropouts and the X-Fusion rear shock is perhaps not quite as composed as a Fox, but neither of these things are deal-breakers. The real issue is whether you actually need a bike that does what the Golden Willow does. For many riders, it’s the challenge of cleaning a steep climb or nailing a near-vertical descent that’s the attraction of riding, and being able to adjust your frame angles through 6° may be seen as diminishing that a little. And on many typical UK rides, there simply aren’t the extremes of terrain that let the Golden Willow shine – it’s at its best on rides with sustained steeps in either direction, on more rolling, traversing trails it hardly seems worth adjusting, as you’ll be adjusting it back in 20 seconds.

We can certainly see the appeal for certain parts of the country, though. On rocky, granny-ring climbs there aren’t many bikes as effective as this, and we were getting quite enthusiastic about the “superhardtail” feel of the bike in 120 rear/150 front/66° head angle mode…

Ups and downs

Positives: Works exactly as claimed, genuinely innovative, surprisingly easy to use, good value

Negatives: May not be entirely necessary for your usual riding, lightweight frame may prove limiting

Verdict

It’s rare that something genuinely new comes along in MTBing, but Bionicon’s user-friendly on-the-fly attitude (in all senses) adjustment is properly different. And it works – despite our initial scepticism, under the right circumstances you’re getting actual bona fide benefits. The only real question to answer is whether you actually need it, and we’ll have to leave that to you. There’s no denying, though, that it’s one of those features that you find yourself relying on…

Ratings

Performance: 4/5
Value: 4/5
Overall: 4/5