Ridley Kanzo Fast GRX Di2 Classified first ride review

Aero gravel bike with a unique drivetrain

GBP £5,459.00 RRP | EUR €6,000.00
Pack shot of the Ridley Kanzo Fast GRX Di2 Classified gravel bike
Pros: Road-bike fast; clever drivetrain; stable handling
Cons: Road rims are narrow for big-volume tyres
Skip to view product specifications

Belgian brand Ridley knows a thing or two about riding off-road because it’s been at the forefront of cyclocross for decades. As expected with its heritage in off-road racing, and the growth of gravel, Ridley’s Kanzo Fast GRX Di2 Classified has been built with speed on its side.

Advertisement MPU reviews

In fact, at first glance it looks like an iteration of the brand’s aero road series, the Noah, because it borrows so much tech and design from this slippery machine.

Ridley Kanzo Fast GRX Di2 Classified frame and geometry

The frame meets a gravel-specific one-piece bar/stem that routes all the cables through the head tube using Ridley’s F-steerer tube, which is crescent shaped to allow the cables/hoses to run through the front of the head tube.

The frame’s tube shapes use the same F-tubing profiles as the Noah Fast, but the design is tweaked to offer big tyre (42mm) clearances front and rear, and a head tube that’s a couple of degrees slacker than the Noah at 71.5 degrees for more stable steering off road.

Seat angle (degrees)74.573.57372.573
Head angle (degrees)717171.571.572
Chainstay (cm)42.542.542.542.542.5
Seat tube (cm)4749.55254.557
Top tube (cm)52.254.756.558.760.1
Head tube (cm)11.514.416.819.722.1
Bottom bracket drop (cm)
Wheelbase (mm)1,0011,0171,0261,0441,053
Standover (cm)78.981.684.186.889.3
Stack (cm)53.756.358.761.363.8
Reach (cm)37.33838.539.340

Ridley Kanzo Fast GRX Di2 Classified kit

The biggest difference is that the Kanzo Fast is designed around a 1x drivetrain – but cleverly retains an impressive breadth of gearing by teaming up with fellow Belgian brand Classified.

Ridley has incorporated Classified’s unique internal 2-speed rear hub, which is wirelessly controlled by a sender that works with the left-hand GRX Di2 shifter and a receiver built into the rear thru-axle.

This means the 1x drivetrain, with a 48-tooth chainring and 11-34 cassette, gives you 22 gears, and is a close equivalent to running a 48/34 double chainring setup.

It’s impressive because the advantages of 1x are all here: chain retention is great, thanks to the GRX’s built-in clutch, and shifts are quick and positive across the Classified cassette.

The drivetrain, which mixes a Shimano mech and chain with Rotor chainring and the aforementioned cassette, is a little noisier than an all-Shimano affair but no more so than myriad bikes that mix brands.

Ridley claims a 1,190g frame weight and 490g for the fork, and my size large complete bike tips the scales at 8.92kg, which is good for a gravel bike running 40c tyres.

Ridley Kanzo Fast GRX Di2 Classified ride impressions

Road or trail, the hub works superbly. A click on the Di2 trigger and the move is instantaneous. In fact, it’s so quick it takes you by surprise, with none of the delay of even the very best front mechs.

Even when shifting under pressure, you can switch ratios on the steepest climbs without hesitation.

The hub itself contains no battery, instead relying on the smart wireless thru-axle with a battery inside. Gear changing is actuated by induction coils in the axle magnetically moving the hub internals between the two ratios in just 150 milliseconds, a single micro-USB charge is claimed to offer over 10,000 shifts.

I’ve only had the bike for a couple of weeks and ridden around 275 miles so far, and it hasn’t put a foot wrong, so initial impressions are very positive.

Ridley Kanzo aero carbon seatpost with a Selle Italia XL-R saddle
An aero post means there’s no chance of a dropper replacement.
Russell Burton / Immediate Media

The ride is firm but offset by a compliant seatpost, great saddle and big-volume 40c tyres. Off-road the stable steering’s solid, while the aggressive ride position encourages you to go fast.

The aero-shaped seatpost means you can’t fit a dropper post, which limits its off-the-beaten-track appeal. Still, if your intentions are byways and fire roads, then this is one lively option.

On the road it feels every inch a road bike, albeit one with slightly slower steering than most. It’s not a negative, but just something you need to become accustomed to when cornering on descents.

The frame comes fitted with proper mudguard mounts front and rear, and I like the idea of fitting the Kanzo with full-’guards and big-volume road tyres because it would make an awesome winter ride.

Ridley Kanzo Fast GRX Di2 Classified is equipped with Shimano GRX hydraulic disc brakes
Shimano’s GRX brakes are competent and consistent.
Russell Burton / Immediate Media

My one niggle is the wheels. The Forzar Vardar DB carbon wheels are well put together; they are very rigid and work with the WTB tyres to provide a leak-free tubeless seal.

However, the rim profile is a road-bike narrow 17mm internally, which shapes the 40c WTB tyres with a bit of an outward bulge in the sidewall. At higher pressures – around 50 to 55psi – the tyres are stable enough, but drop down into lower pressures for when the trail gets really rough and the tyre can wallow somewhat side to side, especially on the front.

Ideally, I’d like to see Ridley build this bike with a more modern, wider rim to make the most of bigger-volume tyres; it’s odd to mix such a forward-thinking aero-chassis and a potentially game-changing rear hub/drivetrain with a slightly dated rim shape.

If I had the Kanzo for longer, I’d look to drop the tyre size from the 40s fitted to a 35 to 38c gravel tyre that’d better cope with its narrow foundation.

Ridley Kanzo Fast GRX Di2 Classified early verdict

Overall, I think that the Kanzo Fast is a superb gravel race machine that’s versatile and light enough to be your one-bike-for-all in this Classified hub build.

The drivetrain has the potential to be revolutionary, although I haven’t tested it yet in tough terrain and rough weather.

Advertisement MPU reviews

It’s a uniquely brilliant mix of aero, gravel and rear 2-speed 1×11 drivetrain.

Product Specifications


Price br_price, 5, 3, Price, EUR €6000.00GBP £5459.00
Weight br_weight, 5, 6, Weight, 8.92kg (L), Array, kg
Brand br_brand, 5, 10, Brand, Ridley bikes


Available sizes br_availableSizes, 11, 0, Available sizes, XS, S, M, L, XL
Brakes br_brakes, 11, 0, Brakes, Shimano GRX BR-RX810 hydraulic disc
Cassette br_cassette, 11, 0, Cassette, Classified, 11-34
Cranks br_cranks, 11, 0, Cranks, Rotor Aldhu Aero, 48T
Fork br_fork, 11, 0, Fork, Full carbon
Frame br_frame, 11, 0, Frame, 30T HM Carbon
Front derailleur br_frontDerailleur, 11, 0, Front derailleur, Shimano GRX Di2
Handlebar br_handlebar, 11, 0, Handlebar, Ridley Aero C1 (one piece) (42cm) with out-front Garmin mount
Rear derailleur br_rearDerailleur, 11, 0, Rear derailleur, Shimano GRX Di2
Saddle br_saddle, 11, 0, Saddle, Selle Italia XL-R with alloy rails
Seatpost br_seatpost, 11, 0, Seatpost, Ridley Kanzo aero carbon
Shifter br_shifter, 11, 0, Shifter, Shimano GRX Di2
Stem br_stem, 11, 0, Stem, Ridley Aero C1 (one piece) with out-front Garmin mount
Tyres br_tyres, 11, 0, Tyres, WTB Venture TCS 700x40c
Wheels br_wheels, 11, 0, Wheels, Forza Vardar DB carbon 622x17c – rear wheel with Classified hub