BMC Fourstroke frame review

Can BMC's CNT carbon rule offroad too?

Our rating 
4.0 out of 5 star rating 4.0

Our review

Super expensive, but it’s definitely a superlative featherlight trail bike for your money
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Swiss bike builder BMC has an ultra-high performance reputation on the road, and bikes like the Fourstroke look set to drag it onto the dirt, too.


Frame: super-carbon feathery goodness

Even being Swiss isn’t enough to justify £2500 for a frame, but then this is no ordinary carbon frame. BMC is the only bike builder licensed to use Easton’s CNT technology in its frames, immediately giving them a strength-to-weight edge right from the raw material up.

‘Integrated Skeleton Design’ reinforces key areas, while the big blown, swooping shapes of the ‘Scapular Negra’ swingarm play to carbon’s natural strengths. A combo of broad lower and wraparound rocker link – both single-piece sections – creates a really tight link between the two frame halves.

Ride: technically impressive, cool & controlled

We were slightly surprised by the short length of our 19in ‘Large’ ride sample, which was more like most mediums we ride. Although with a bike weight of just under 24lb we weren’t turning our lungs inside out on the climbs, we’d certainly size up if your bike is going to spend a lot of time with a race number on the front.

An impressive technical aptitude for such a lightweight bike is what dominates our lasting impression of the Fourstroke. While most bikes this weight climb, accelerate and chop from line to line with insolent ease, it’s the way the BMC stayed controlled and coolly calm in more chaotic sections that made it memorable. Bootleg’s mix of deep sand or sharp rock trail edges give them zero tolerance when it comes to wrong moves or excess speed/limited skill moments, but the BMC never got flustered.

The VPS suspension certainly creates a very neutral trail connection. It balances smooth compliance and traction with pert pick-up and kick that adds even more zip to the BMC’s totally astonishing acceleration.

Rapid reaction speed is definitely cross-country style though, with steep head and seat angles putting you right over the action for maximum snatch steer agility. The longer-than-average tail end adds a stabilising effect, though. That’s great for confidence at speed, but you do have to learn to turn in a fraction later on tight stuff to compensate.

Components: take your pick

In Switzerland, BMC rolls out two different complete bikes on the Fourstroke 01 chassis, as well as cheaper hydroformed alloy FS02 versions. UK distributor Extra is concentrating on the frame-only packages for now, but you wouldn’t go far wrong configuring your bike around the setup of our US sample ride. The fact that the weight still comes in at under 24lb without fitting any stupidly light kit shows what could be done with a proper fanatical fit, although it’d be a shame to dress it up so light that the ride is compromised.

Summary: oustanding


Even by expensive bike standards, the BMC is a lot of money, but if you want exclusivity and a truly top-echelon ride then it’s worth paying. Its blend of breathtakingly low weight and responsiveness underlined by a sturdily surefooted ride feel is genuinely outstanding, and you’d almost certainly have the only one on your street.

Product Specifications


Name Fourstroke FS01
Brand BMC

Spokes Brand DT Swiss
Cassette Shimano XTR M970-9 11-32T
Fork Fox 32 F100RL - 100mm
Front Derailleur Shimano XTR
Head Angle 71
Rear Derailleur Shimano XTR
Saddle Filante
Seat Angle 73
Stem EA70
Available Sizes 15 Inches 17 Inches 19 Inches 21 Inches
Front Tyre Racing Ralph
Front Tyre Size 26x2.25
Rear Tyre Racing Ralph
Rear Tyre Size 26x2.25
Max. Fork Travel 100mm