AX Lightness Vial Evo D review

Superbike? Nah, this one’s an überbike

Our rating 
5.0 out of 5 star rating 5.0

Our review

The Vial Evo Di is not only ashtonishingly light, it's also an ashtonishing performer. The price will leave you equally astonished
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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?

  • Highs: Astonishing weight, performance
  • Lows: At €11,800, the cost is equally ashtonishing

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:
Jonny Ashelford

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:
Jonny Ashelford

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:
Jonny Ashelford

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.

Product Specifications


Name Vial Evo D (14)
Brand AX Lightness

Description AX Nasdorowje cages
Brakes Dura-Ace
Fork THM Scapula CT
Frame Material Carbin
Front Tyre Continental Grand Prix 4000S II
Handlebar AX 4200 Ergo
Rear Tyre Continental Grand Prix 4000S II
Saddle AX
Seatpost AX Europa
Shifters Shimano Dura-Ace Di2
Stem AX Rigid
Weight (kg) 5.28
Wheelset AX-Lightness Ultra Road clincher
Year 2014
Weight (lb) 11.46
Frame size tested L