New BMC Fourstroke gets self-dropping dropper seatpost and updated frame

By Luke Marshall

Published: Wednesday, 05 October 2022 at 12:00 am

BMC has updated its Fourstroke cross-country mountain bike, with a new frame seeing refreshed suspension layout, updated geometry and increased water bottle capacity.

BMC has released three new Fourstoke models. The Fourstroke and Fourstroke 01 have 100mm of travel front and rear, and Fourstroke LT which has 120mm of travel front and rear. While these three bikes share the same frame, differences in carbon construction, suspension travel, and dropper post technology make each suitable for different types of cross-country riding.

A highlight from the range is the Fourstroke 01, which includes BMC’s Autodrop dropper post – the first-ever fully integrated automatic dropper seatpost.

BMC has introduced plenty of new specifications across the three new models. The Fourstroke has four specifications to choose from with prices ranging from £4,300 / $4,699 to £7,200 / $7,999.

The Fourstroke 01 has three models plus a frame kit. Pricing ranges from £5,800 / $5,999 for the frameset to £12,400 / $13,499.

Finally, the Fourstroke LT range includes three specifications with prices starting at £4,500 / $4,999 and going up to £11,499 / $12,499.

BMC APS updated

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The shock now sits under the top tube but BMC still uses its twin-link APS suspension platform to fine-tune the kinematics.
Paul Foulonneau

The most obvious change to the BMC Fourstroke from its predecessor is the bike’s new suspension layout.

BMC still uses its twin-link APS (Advanced Pivot System) suspension to drive the shock. However, the shock now sits horizontally underneath the top tube rather than vertically.

BMC says it updated the kinematics of the system to increase traction and suspension performance on climbs and descents. In addition, BMC believes the virtual pivot designs allow it to design complex kinematics with performance gains that outweigh those of lightweight systems such as flex stays and single pivots.

BMC has tuned the Fourstroke’s anti-squat to fall off through the travel to keep the suspension active deeper in the travel while maintaining pedalling efficiency nearer the sag point.

All-new Autodrop

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The Autodrop post is integrated into the frame and provides 80mm of travel.
Paul Foulonneau

The new Autodrop dropper post technology is available on the Fourstroke 01 range of bikes. The two-position dropper post has 80mm of travel.

Unlike all other dropper posts, the Autodrop allows the rider to drop the post automatically without squatting on the saddle to lower it.

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This valve on the outside fills an air tank in the downtube which is used to activate the dropper post with the need for the rider to lower it by sitting on it.
Paul Foulonneau

Inside the downtube of the frame is an air tank. This is filled via a port on the seat tube. When you press the dropper lever, the pressurised air runs through a hose to compress a spring in the dropper post, dropping the post without you having to sit on the saddle.

Pressing the dropper lever again returns the saddle to its pedalling height. No details were given on how many times this can be used before the tank needs to be topped up to keep the pressure correct for activation.

BMC claims Autodrop is for the race enthusiasts who want the maximum time powering on the pedals without having to sit down before dropping into a descent. If you’re using a dropper post dozens of times per race, the fractions of seconds saved by using the Autodrop post could amount to valuable time and energy savings.

The Fourstroke 01 bikes feature an additional port on the seat tube to provide easy access for Autodrop maintenance.

The Foustroke and Fourstroke LT use a conventional dropper post.