The world of superbikes is littered with show-stoppers that are more likely to be hung up and admired rather than ridden. The German high-tech specialist AX doesn’t think like that. When BikeRadar's sister publication Cycling Plus requested an AX Lightness Vial Evo D for a superbike feature, the Bavarians responded with: “We would rather you rode and tested the bike.” Well, who were we to argue?
The Vial weighs an astonishing 5.28kg – a full 2kg lighter than our tester’s Dura-Ace-equipped carbon bike. That the Vial so easily hits the high notes for performance pretty much raises the bar to a whole new level. The attention to detail is impressive, too.
AX doesn’t like sloped/cone-shaped headset tops – so it has made its own, just 3mm thick. And AX’s own uni-directional carbon seat collar is a mere millimetre thick.
THM’s Scapula CT fork hardly troubles the scales at 295g
The geometry is aggressive, with parallel steep 73.5 angles, a 98.4cm wheelbase, 17.5cm head tube and 56.5cm top tube. That should make the handling snappy, even twitchy, which is where AX’s mastering of carbon takes over.
The slender seat-tube – which is barely wider than the 27.2mm post sitting atop it – narrows into a squared-off profile just above the bottom bracket shell. This allows the seat-tube to flex, and in tandem with the super-skinny seatstays creates a rear end that not only isolates you from vibrations but puts your weight firmly over the rear wheel. This provides superb traction when cranking it at speed through corners. All you need to do is head into a corner at high speed, look towards the apex and you’re through it. Riding successive twists is like threading a needle through silk – no drama, no fuss, just pure speed.
AX doesn’t like cone-shaped headset tops – so it made its own
The bike’s beautiful balance, low weight and Ultra Road clincher wheels – that weigh just 1,060g per pair – make this one of the best climbers we’ve tried. It’s less like powering a bike uphill and more like running – but without the irritation of your feet hitting the ground.
The AX wheels have 28mm deep and 26mm wide rims that shape the tyre superbly. They’re laced to Extralight hubs using DT spokes. The rims have reinforced spoke holes and use continuous fibres for strength. The seamless brake track isn’t machined but braking was excellent in the dry (surprisingly we had no rain during testing), easy to modulate and noise-free. AX told us it tested the rims with a 120kg rider on Alpine descents to ensure their strength.
AX uses a mix of carbon types to ensure optimum strength where needed
The Vial Evo is by far the lightest Di2 bike we’ve ever seen and represents a new achievement for low weight. Yes, the kit is all suitably high-end, but what impresses most is its phenomenal ride.