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

By Oscar Huckle

Published: Wednesday, 22 February 2023 at 12:00 am

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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.

A striking frame

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.

Oscar Huckle / Our Media

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.

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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.

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Introducing Autodrop

 

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.

A dependable spec list

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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.

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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.

BMC provides its own finishing kit, with a MFB01 carbon handlebar in a 760mm width and its MSM01 stem in a 60mm length. A Fizik Antares R7 saddle sits atop the Autodrop dropper post.

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

 

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