On-One Carbon 456 X9 review

Incredible on paper but brutal on the trail

Our rating 
2.5 out of 5 star rating 2.5
GBP £1,499.00 RRP | USD $2,377.00
On-One Carbon 456 X9

Our review

Amazing kit value, but harsh frame feel undermines control and comfort without helping power delivery
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The direct descendant of the have-a-go-hero steel 456 and the superb Ti 456, On-One’s carbon fibre 456 sounds like a guaranteed success. Brutal riding stiffness and contrasting drivetrain softness undermine the obvious value of the package but it’s still a bargain for short blasts.


Ride & handling: Extremely stiff but big tubes aren’t matched by big power output

The carbon frame, top-drawer componentry and contemporary super-slack head tube angle that puts the front wheel way out front for self-correcting stability meant we had high expectations of the 456 X9 when we hit the trails. Unfortunately we were literally in for a shock. 

Despite the decent RockShox Revelation fork, the brutal stiffness of the mainframe gave us a proper beating through our hands and feet even on short – albeit rocky – descents. In fact, if we didn’t pull over and shake our hands out halfway down the hill, arm pump became a real problem when trying to keep pace with the other, more forgiving bikes. 

While the tyres and Motion Control fork damping did their best, the sharp edge to the ride feel also undermined traction and confidence at higher speeds. This wouldn’t be so bad if it was similarly rigid and responsive on the ups, but despite serious tube sizes the carbon sucked out a lot of power kick with a definite soft feel underfoot.

The super-slack seat angle made standing essential in order to stop the front wheel wandering off or popping up on uphill corners. Add the fact that back wheel chatter undermines traction and, despite a low weight and the temptation of that killer spec, the Carbon 456 is definitely an acquired taste.

Frame & equipment: Carbon chassis is a head-turner; fork and X9 kit are great for the money

The frameset certainly looks promising. The multi-faceted mustard pot shaped head tube backs onto a huge headstock area. This then runs into a massive boat-shaped down tube, which extends the full width of the bulbous bottom bracket block. 

The D-section top tube joins into the 31.6mm diameter seat tube with a big wraparound knuckle and the wishbone top to the seatstays is a mighty chunk of fibre too. Suitably slab-sided chainstays sprout from the bottom bracket, ending in modular dropout plates that can be switched to work with conventional quick-release or 135mm through-axle wheels. 

There’s a huge amount of tyre room too, and an optional down tube/chainstay route for the rear brake hose. The multiple-rivetted cable guides under the top tube look untidy though, and it’s a gapped rather than completely enclosed run, which potentially means more maintenance will be needed to keep it smooth.

There’s little to complain about with the kit though. The Revelation RL fork with 20mm Maxle is super-precise in steering terms and very controlled in all but the most chaotic conditions. Avid Elixir brakes are a benchmark for control and in transmission terms you’re getting SRAM X9 at an X5 price.

The On-One wheels are usefully sturdy and the Maxxis CrossMark tyres are fast but capable of taking some hammer. Middling width bars on our sample can be swapped for a monster 810mm set if you want too.


This article was originally published in Mountain Biking UK magazine, available on Apple Newsstand and Zinio.

Product Specifications


Name Carbon 456 X9 (12)
Brand On-One

Description Maxxis CrossMark, 26x2.25in tyres
Headset Type On One Smoothie
Weight (kg) 11.64
Stem On One Ultralight, 70mm
Shifters SRAM X9
Seatpost On One Twelfty 31.6mm
Seat Angle 69
Saddle On One Bignose
Rims On One Max
Rear Wheel Weight 2440
Rear Derailleur SRAM X9
Head Angle 66
Bottom Bracket SRAM GXP
Handlebar On One Riser, 685mm
Grips/Tape On One Tickety Boo lock-on
Front Wheel Weight 1980
Front Derailleur SRAM X9
Frame Material High modulus carbon fi bre with modular dropouts
Fork RockShox Revelation RL Dual Air Poplock Maxle 20mm axle, 140mm (5.5in) travel
Cranks SRAM X9, 22-32-44T
Chain SRAM PC1070
Cassette SRAM PG1070, 10-speed 11/32T
Brakes Avid Elixir CR hydraulic 160mm disc
Weight (lb) 25.66