Bionicon's on-the-fly adjustable full suspension design aims to solve some of the bugbears of mid-travel all-mountain bikes. Surprisingly, it works pretty damn well.
The £1,860 Edison Ltd 2 serves up a unique cocktail of 140mm (5.5in) rear and 70-150mm (2.75-5.9in) front travel, with on-the-fly travel and geometry adjustment courtesy of a nifty bar-mounted button.
The ride: expectations defied
You can sometimes get the measure of a bike from a glance at the numbers, but the Edison's hugely variable geometry and front end travel completely defies categorisation. The specs suggest the top tube is on the cramped side of short, but in standard full travel set-up the laidback seat angle and adjustable stem make it easy to get comfy.
Making use of the Edison's adjustability takes a bit of practice, so it pays to do a bit of thinking ahead. Steep climb coming up? Shift early, push the big button and shift your weight forward. Fast, rocky descent? Push the button and sit well back.
Once you've got your head round the way it works, it's easier than any other variable travel/geometry system we've tried. In either setting, the Edison's suspension is fluid and composed. The front end in particular blends impressive torsional rigidity with a bump-sucking eagerness, but the rear doesn't let the side down. This bike is at its best being pedalled hard as possible down a fast and twisty singletrack trail.
The perfect all-rounder? Well, not quite. While we like the adjustable geometry and travel, it doesn't make climbs a real pleasure – more like 'less of a chore”, like most 140mm travel, 30lb-plus machines. But if you ride all day and live for descents, it's a very tempting and highly effective alternative to the mainstream.
Chassis: the fork tube's connected to the shock tube
At a casual glance the Edison looks like a regular old school single pivot machine. An asymmetric swingarm pivots just behind the bottom bracket and above the middle chainring.
The main frame is built around a chunky, roughly oval section down tube, reinforced at the head tube with a large gusset. A slender dropped top tube increases standover clearance and large plates attach the shock mount and seatmast assemblies to the down tube. The whole lot - right down to the tidy weld beads - screams functional simplicity. It ain't elegant, but it gets the job done.
What makes the Bionicon unique is the way the fork and shock are connected - via a 'slave' air chamber that screws onto the end of the shock's piston, a handlebar-mounted button, and a series of pipes running through the frame that link it all together.
Ride as normal and you've got access to the full 140mm rear and 150mm front wheel travel. Push down on the bars while pressing the bar-mounted button, and air is transferred from the fork to the slave shock chamber to reduce the fork's travel and extend the slave air chamber's piston, helping to keep the bottom bracket height and frame geometry consistent, even with the reduced fork height.
Reduced fork height helps make lighter work of climbs, because it reduces the front end's tendency to wander. But because it's been achieved by removing air from the fork, the spring rate stays the same, so the fork is just as plush on the uphill bits as it is on the downs.
It sounds complicated but works brilliantly, provided you follow the set-up instructions to the letter. Our one beef is that the ludicrously miserly fork brace clearance makes a mockery of typically claggy UK winter trails.
Equipment: SRAM stop & go, unique stem
Our test Edison Ltd 2 came with an SRAM X-9, X-7-based transmission and Avid's Juicy Five brakes. If the price is a bit rich, the £1,480 Ltd 3 has the same frame, shock and fork but substitutes X-7 and X-5 gears and Juicy Three stoppers.
Both bikes sport another Bionicon exclusive - a proprietary stem that allows handlebar position to be adjusted over a wide range of fore and aft positions.