Bike of the Week

Dec 01, 2023

Fourstroke XC bike features updated frame with self-dropping dropper post

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By Oscar Huckle

Published: February 22, 2023 at 10:00 am

Launched in October 2022, BMC's Fourstroke has arrived at BikeRadar HQ for testing.

The brand's cross-country mountain bike was updated with a new frame featuring refreshed geometry, increased water bottle capacity and a new suspension layout.

This is a race bike through-and-through, with 100mm of suspension travel on tap.

However, if you’re after a bike that's more capable on gnarlier tech, BMC also launched a Fourstroke LT with 120mm of travel front and rear.

Let's take a closer look at the build.

The Fourstroke looks fast standing still and the frame sports BMC's top-tier 01 level carbon fibre construction.

It uses BMC's twin-link APS (Advanced Pivot System) suspension design, with the shock now sitting horizontally under the top tube rather than vertically.

The frame is also visually different to its predecessor and is easily identifiable from the second vertical strut on the driveside. BMC claims this increases pedalling efficiency by 20 per cent.

The bottom bracket area has also been beefed up and the bike can accept up to 2.4in mountain bike tyres.

There are five strategically placed bottle cage bosses on the down tube, so you can fit up to two bottle cages. BMC says if you’re using two, they need to be side-loading and they can't have a greater capacity than 550ml.

The Fourstroke's geometry has been updated too, with the head tube angle a degree slacker at 66.5 degrees.

The effective seat tube angle has been steepened to 76.7 degrees. The reach is 457mm on a size medium and all sizes sport a 432mm chainstay length.

Every fortnight, we’ll bring you a detailed first look at one of the latest bikes (or framesets) to arrive at BikeRadar HQ – from road to commuting, gravel to enduro, and anything in between.

This is our chance to introduce the bike and everything that makes it unique before hitting the road or trails.

Head to our Bike of the Week hub for previous editions.

All of the Fourstroke 01 models come with BMC's new Autodrop dropper seatpost.

This is a two-position dropper post with 80mm of travel, enabling you to drop the post automatically without having to put your weight on the saddle. This saves the need to stop pedalling to focus on moving the seat out of the way – simply press the remote lever at the bar – which will be very advantageous in a race scenario.

This is thanks to an air tank located inside the down tube, which compresses a spring in the dropper post when you actuate the lever.

There's a valve on the non-driveside face of the seat tube to inflate it.

The Fourstroke 01 Two retails for a heady £8,800 / $9,499 / €8,999.

The range starts at £4,300 / $4,699 / €4,299 for the Fourstroke Four with a Shimano Deore drivetrain.

It tops out at £12,400 / $13,499 / €12,999 for the Fourstroke 01 LTD, which is bedecked with SRAM XX1 Eagle AXS and Fox's Float 32 SC Factory fork and Float DPS Factory shock.

This particular build comes with a RockShox SID SL Select+ fork and matching SIDLuxe Select+ shock. BMC uses the RockShox TwistLoc remote lockout front and rear.

The bike is specced with SRAM's GX Eagle wireless electronic groupset, with BMC speccing a 34t chainring. SRAM is also on stopping duties with its Level TLM disc brakes.

DT Swiss XR 1700 mountain bike wheels are a fitting addition to the build, featuring a 25mm internal rim width. The brand specs its venerable 350 hub, with straight-pull spokes lacing it to the rim.

They’re wrapped in Vittoria Mezcal mountain bike tyres in a 29×2.35in width.

All-in, our size-large test bike weighs 11.6kg without pedals.

Technical writer

Oscar Huckle is a technical writer at BikeRadar. He has been an avid cyclist since his teenage years, initially catching the road cycling bug and riding for a local club. He's since been indoctrinated into gravel riding and more recently has taken to the dark art of mountain biking. His favourite rides are epic road or gravel routes, and he has also caught the bikepacking bug hard after completing the King Alfred's Way and West Kernow Way. Oscar has a BA degree in English Literature and Film Studies and has close to a decade of cycling industry experience, initially working in a variety of roles at Evans Cycles before joining Carbon Bike Repair. He is particularly fond of workshop tool exotica and is a proponent of Campagnolo groupsets. Oscar prefers lightweight road and gravel frames with simple tube shapes, rather than the latest trend for aerodynamics and full integration. He is obsessed with keeping up to date with all the latest tech, is fixated with the smallest details and is known for his unique opinions.

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