The adjustable mountain bike stem is here, and we’re not sure we need it

One adjustable component, three stem lengths – an innovation too far?

Spanish firm 3FStech has, in its own words, come up with a product that will be an ‘evolution in mountain bike racing’. What it’s actually done is designed an adjustable mountain bike stem.

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Indexed through three positions, the 3FStech AIM (adjustment in motion) stem slides along its own alloy shaft to offer 55, 95 and 120mm stem lengths to a rider.

Related: How the pros set up their stems and handlebars

With the 350g 3FStech AIM in place, a rider simply pushes forward on a remote lever and either pushes out or pulls in the component to reach their desired stem length. Should you want to risk an accident, it can even be done while in the saddle.

No, it’s not april 1st:

Many of us will have resorted to adjusting stem lengths over the years – and anyone who has will be able to report on the dramatic effect that doing so will have on a bike’s steering.

The 3FStech’s ‘downhill’ setting, the shortest on offer, places the bar 55mm from the centre of the steerer tube, which is still 20mm further out than many regular stems, and that’s a big difference.

Next there’s the ‘trail’ setting, presumably where 3FStech reckons a trail rider would spend most of their time. In this position the AIM provides 95mm of stem length, and to get to that point the stem then provides a seven-degree drop – which puts you fully in race cross-country bike territory, something that would be inappropriate for most enduro bikes.

Another slide of the stem and you’re in climbing mode, with a massive 120mm of length and a very harsh 20 degree drop.

One concern we have is that, from pictures at least (see GIF in gallery, above), it seems that the extension of the AIM stem is so great that it could actually cause damage to your frame at full lock or in a crash scenario.


Add to that the fact the sliding interface will have to deal with endless mud and grit, the extra stiffness it would require, plus its vulnerability in a crash and this is one innovation we’re going to take some convincing about.

Your stem length is critical to your bike’s handling and will have been a big consideration when its frame was designed – so our first suggestion would always be to buy a frame that fits correctly.

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Nevertheless, we could be proven wrong, and for some people this might just make sense (if that’s you, you can pledge cash via the Kickstarter page). But for now we’ll file it in the Kickstarter ‘weird and wonderful’ archive.