BMC Fourstroke Prototype XC Bike Teases SRAM Release Date

Posted on September 2, 2022 by Cory Benson

BMC’s full-suspension XC Fourstroke mountain bike looks set for a complete overhaul if that prototype raced the mountain bike world championships with the new SRAM Eagle AXS. Additionally, BMC seems to have let slip a real timeline for the release of that prototype next-gen direct-mount SRAM Eagle AXS derailleur we spotted on Nino’s Scott.

We will only have to wait a month to have all the details…

BMC Fourstroke All-New Prototype XC Bike

vs. an anonymous Bikerumor fan

During last weekend’s UCI XC MTB World Championships in Les Gets, a few riders from the BMC MTB Racing team were spotted riding a new, as-yet-unreleased prototype XC BMC Fourstroke carbon mountain bike, featuring an all-new shape of tubing and a re-oriented shock layout.

Additionally, both of these riders’ bikes also appear to be built with the same prototype BlackBox SRAM Eagle AXS direct mount derailleur, the same hollow Eagle FlatTop SL (T-type) chain and the same new XX1 SL Eagle cassette with 3 machined sprockets. alloy that we spotted on N1N0’s bike.

Check out our Pro Bike Check of 10x World Champion Nino Schurter’s setup for more details on everything we know about this prototype SRAM Eagle AXS drivetrain – the patents we discovered years ago, the performance gains expected and UDH compatibility.

Filippo Colombo and Titouan Carod were both on the new BMC Fourstroke prototype, with Filippo earning an XCC podium and an XCO top ten on the unreleased bike.

Interestingly, Pauline Ferrand-Prevot opted not to race the new bike, but to race the BMC Twostroke carbon hardtail instead, in order to benefit from lighter weight and improved efficiency. for the climbs of Les Gets. It seemed like a good move as she won the World Championship title in both short track XCC and Olympic distance XCO.

What do we know? BMC technical details

Unreleased BMC Fourstroke prototype with BlackBox SRAM XX1 Eagle AXS SL derailleur, racing worlds

vs. Filippo Colombo, photos by Maxime Schmid & 3SO The Agency

BMC has yet to share any details about the new bike. But the most obvious change for BMC, which has long believed that a vertical shock orientation provides the best performance… the unreleased BMC Fourstroke prototype moves to a horizontal shock layout.

It still appears to be a short-link 4-bar with a unified rear triangle and a small rocker driving the shock. But now the rear triangle has moved to a more symmetrical design with an upright strut connecting the seat and chainstays on both sides of the bent seat tube, and a post-mount brake now on the seatstay.

The downtube drops a bit at the bottom bracket, presumably to make more room inside the main triangle. Those Fourstroke prototypes we’ve seen don’t appear to include a cage mount on the seat tube. But they seem to have 5 water bottle bosses on the downtube. Riders at Worlds only had one bottle cage in the second lowest position, but surely that would allow for 2 bottles or a tool/spare rack bolted under a full size water bottle?

Unreleased BMC Fourstroke prototype with BlackBox SRAM XX1 Eagle AXS SL derailleur, race UCI XCC World Championships

vs. Filippo Colombo, photos by Maxime Schmid & 3SO The Agency

The new BMC Fourstroke prototype gets a steeper top tube more in line with the seatstays and appears to feature a boxier tube shape at the rear, with the same pointed seat stay caps and hidden hardware. Up front, the main triangle is a little more rounded than the current angular bike. The new bike retains the built-in short travel GDR elliptical dropper seatpost, now in gloss ano silver, and moves its internal cable routing from the bottom of the downtube, to the sides of the head tube.

And of course, it switches to the new UDH(?) compatible SRAM direct mount rear derailleur.

Details of the unreleased BMC Fourstroke downtube prototype

vs. BMC

Even though it is a completely different suspension design than the current Fourstroke, we are pretty sure it will keep the same name. How? These teaser images on BMC’s homepage are named “Fourstroke”.

BMC isn’t really hiding the unreleased Fourstroke prototype either. In fact, the new bike is now on their homepage, and you can sign up to be one of the first to get all the details:

Are you looking for something special in Les Gets? Sign up to be the first informed.

BMC Fourstroke & SRAM Eagle AXS coming soon? !

Unreleased BMC Fourstroke prototype with BlackBox SRAM XX1 Eagle AXS SL derailleur coming October 5, 2022

vs. BMC

Clicking on BMC”Tell me moretakes you to a page titled “The Final Countdown” with a clock counting down just over a month to the October 5 reveal.

And see what stands out from the bottom of this photo above at the end of the new Eagle FlatTop SL chain?

This is the new SRAM XX1 Eagle AXS direct mount derailleur!

But instead of being stealthily all black like the BlackBox prototypes on Filippo Colombo’s new bike or the one ridden by Nino Schurter…this one has polished alloy on the top direct mount of the B-knuckle. It looks very much like a ready-to-eat finished product. So it looks like SRAM will have to launch it before October 5, 2022 if this new BMC goes live in just 32 days.

Tick, tock!

Wiley C. Thompson