The BMC Trailsync is a revolutionary new dropper post from BMC that automatically flips between suspension settings as you change your saddle height.

We’ve all done it. After a long climb you lower your saddle and drop into a steep chute but no sooner have you set off than you realise you forget to open up the lockout on the shock. Not with Trailsync.

The knee bone’s connected to the thigh bone

By flipping the shock upside down on the new Speedfox, similar in layout to the new Scott Genius, BMC can run a regular gear cable from the shock to the underside of the Trailsync dropper post.

With both now connected, you push the handlebar remote to drop your saddle height and the rear shock simultaneously flips from trail mode to full open. It’s really is as easy as that.

The 2018 BMC Speedfox

Exclusive to BMC, Trailsync is currently available on the new 2018 Speedfox (120mm travel 29in or 130mm travel 27.5in full suspension trail bike).

The seatpost has three fixed positions: full height, 35mm drop, and all the way down. Total drop varies with frame size: it’s 80mm on the size S, 100mm on the size M, and 120mm on L and XL bikes.

It’s like a fork but not

The handlebar remote cable runs through the top tube and connects to a guiding pin that locates directly into the post, once again it with a regular gear cable for ease of servicing.

The post itself looks a lot like a fork leg and has a 30mm diameter shaft. And the similarities to a fork don’t end there. The post glides on two bushings housed inside the frame, and instead of having a conventional seat clamp the BMC uses a seal head. As such, you can’t remove the post and fit a regular dropper.

If you can’t move the seat post independently in frame how do you set your maximum saddle height?

The short answer is that you need to cut the post down.

To do that you remove the head, loosen the air seal so you can push it further into the post, then chop off the desired amount of post with a pipe cutter. It only takes five minutes and because the head itself has 30mm of height adjustment you don’t need to be too precise.

Also, if you completely mess it up, BMC has an aftermarket head with 60mm of wiggle room that will get you out of a hole.

The seat post is air sprung, where the pressure in the post can be set between 120-180psi to control return speed. That’s higher than most dropper posts and it’s because the air spring needs to be strong enough to overcome the resistance in the spring-loaded compression adjuster on the shock.

With a three-position shock like the Fox Float fitted to the Speedfox you can choose lock out and tail mode as your two setting, or Trial mode and full open, simply by adjusting the cable position.

Is there a weight penalty?

No. Even with the extra cable that connects the seat post to the shock, Trailsync is lighter than the equivalent dropper posts from RockShox and Fox.

How did it ride?

In a word… seamlessly.

Once we got the saddle height dialled in, which took two goes as we were overly cautious with the first cut, Trailsync gives you one less thing to think about when out on the trail.

In that respect it would make a great addition to any bike, but particularly race bikes, where the heat of the moment often means it’s easy to get fluster and simple thinks like opening your shock up for the descent can easily be forgotten.

Unlike other intelligent/automatic shock systems, Trailsync doesn’t complicate matters or have you looking for a way to override the system.

Sure, having access to all three shock modes could prove to be better than just two, as it would allow you to use trail mode in with 35mm drop, locked at full extension and open with the saddle slammed all the way done.

Also, if you’re used to the adjustment of an infinite dropper the three position Trailsync post may seem like a backwards step.

That said, integrated dropper posts like Trailsync are the future, and linking it to the rear shock is nothing short of a stoke of genius on BMC’s part.