B’Twin Rockrider 8XC Replica review

Carbon framed, cross country race bike

Our rating 
3.5 out of 5 star rating 3.5
GBP £899.99 RRP

Our review

Seriously impressive cross-country race hardtail – particularly at this price – but not the best for trail riding
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French-based sports superstore Decathlon specialise in manufacturing their own range of value-orientated products to sell alongside the big brands. B’Twin is their bike line and the 8XC Replica uses the same high modulus carbon frame as the range-topping 8XC race hardtail, but with a toned-down component selection to bring the price in under £900.


Ride & handling: A purist’s race bike, with strength and skill required

Most hardtails these days emphasise comfort, fun and control over outright speed. Not this one. Make no mistake, this is a purist’s race bike with a ride position – and handling characteristics – to match.

The narrow bar, long stem (by current standards) and low front end create a rider cockpit that bears more than a passing resemblance to the setup of a road bike. There’s a good reason for that – it’s a very efficient way to get the maximum power down to the pedals. That, and the fact that cross-country races are won on the pedally bits.

Sure enough, stretched long and low over the bike, the flat back setup combined with the 8XC’s low weight and stiff chassis make for a bike that surges forward with every pedal stroke. 

Plenty of weight over the front and a taut-feeling rear triangle add up to a rear wheel that’s skittish in the rough, demanding constant rider input to keep the power where it’s needed. But pay it the attention it demands, though, and this bike will out-climb almost anything.

Unfortunately, the same can’t be said when it comes to cashing in the gravity credits you’ve earned on the way up. The setup that’s super-efficient for uphill and flat sections is less than ideal for descending, and the low and narrow bar make life particularly difficult through extended sections of technical singletrack.

That’s not to say this isn’t a bike that can’t be ridden quickly downhill, but it’ll take a ballsy, experienced and fluid rider to match the kind of descending speeds that more trail-orientated hardtails make easy. 

This isn’t so much a criticism of the 8XC, more a reflection of its intended use. For out-and-out cross-country racing it’s a gold-plated bargain. But the very things that make it so suitable for contesting a podium finish make it less compelling as an all-round trail bike. You have been warned.

B’Twin rockrider 8xc replica:
Steve Behr/Future Publishing

Frame & equipment: Carbon at an alloy price, and incredibly light spec

Decathlon claim a bare frame weight of 1.15kg (2.54lb). That’s seriously impressive at this price and undoubtedly a big factor in bringing the overall weight in under 11.7kg (25lb) without pedals (although clipless pedals are included).

Unusually for a carbon chassis, the 8XC is made in France rather than the Far East. At least, that’s what it says on the frame sticker – though it’s unclear whether this refers to just bike assembly or frame layup too.

The details are well thought-out. Mud clearance at the rear is huge thanks largely to bridgeless chainstays and a curved seatstay bridge – a plus if you’re intending to keep riding through the worst a UK winter can throw your way. 

Tidy cable routing includes bolt-on cable guides under the top tube, though, making this an uncomfortable bike to shoulder. A nice touch is the neoprene sock covering the whole driveside chainstay, preventing damage – and noise –  from a bouncing chain.

The 8XC race bike on which the Replica is based has a no-holds barred Shimano Deore XT and XTR transmission. The Replica makes do with a SRAM X7 setup, but that’s still a decent spec for the money. 

Shifting is clean and accurate and, with a 22-tooth small ring and 36-tooth large sprocket, the range is enough to get you up the steepest of climbs with the supplied clipless pedals.

That’s if the supplied Hutchinson Cobra tyres keep gripping. Chances are they will in the dry, but the close, shallow tread pattern isn’t a great choice for damp British trails. Avid’s Elixir 3 hydraulic discs are reasonable budget stoppers, while B’twin’s own-brand wheels and contact points round off the Rockrider’s spec list.

As you’d expect from a bike that’s been inspired by a race machine, the stem is rangy and the bars flat and narrow. Many riders might prefer a slightly shorter stem and higher, wider bar. Easy changes to make, though you should expect to pay extra even if you swap at the time of purchase.

The fork, like the frame, is a highlight. An air fork on a bike below £1,000 is a bonus in itself. The fact that it’s an easily adjustable RockShox Recon with a remote, bar-mounted lockout is even better.


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

Product Specifications


Name Rockrider 8XC Replica
Brand B'twin

Bottom Bracket SRAM GXP
Rear Derailleur SRAM X7
Weight (lb) 25
Weight (kg) 11.7
Stem B'twin 100mm
Seatpost B'twin
Seat Angle 72
Saddle B'twin Titane
Rims B'twin comp
Rear Wheel Weight 2700
Headset Type Cane Creek
Brakes Avid Elixir 3 hydraulic disc
Head Angle 69
Handlebar B'twin alu, 23.5in
Front Wheel Weight 2000
Front Derailleur SRAM X7
Frame Material High modulus carbon
Fork RockShox Recon Gold TK air, 100mm (3.9in) travel
Cranks SRAM S1000 44/33/22
Chain SRAM PC1031
Cassette SRAM PG1050 10-speed 11-36t
Tyres Hutchinson Cobra, 26x2.1in