The best mountain bike stems are an important factor when it comes to the control of your mountain bike, but which one should you choose?

Our round-up of the best mountain bike stems in both 31.8mm and 35mm clamp sizes.

Read more: Fancy a whole new cockpit? The best mountain bike handlebars

A mountain bike stem is the bit that connects the handlebars to the fork steerer. They come in different lengths and with different rises. Modern stems are typically between 40mm and 70mm long with bolt at the rear and four bolts at the front.

It is possible to measure differences in weight between models of stem, and if you’re really in tune with your bike, there are subtle differences in stiffness to evaluate. It’s not easy, but keep all the components the same, and ride the same trail over and over again with different stems, and the nuances begin to become apparent.

Equally, get up close and it becomes obvious which stems are really well thought-out and have the best combination of construction, material choice, geometry and even the fasteners — something that’s important on a component that needs to handle big forces.

First job is to work out what stems will actually fit on to your bike. You’ll need to know your fork’s steerer size and handlebar diameter.

Your fork steerer is almost certainly going to be the usual 1-1/8th” diameter (the other option is 1.5in but it’s very rare these days). Use a tape measure to measure the diameter of your headset top cap and you’ll instantly see if it’s not for a 1-1/8th” fork steerer fork.

Best mountain bike stems

These our are current favourite best mountain bike stems. See the links to full reviews down the page.

  • KS Ether
  • Syntace Megaforce 2
  • Funn Crossfire
  • Race Face Turbine R 35
  • Renthal Apex
  • USE Ultimate Vyce 35

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Best mountain bike stems

best mountain bike stems

Syntace Megaforce 2 stem

If money were no object: first choice

Price: €118.00 | Weight: 105g | Colours: Black | Lengths: 30, 40, 50, 60, 70, 80mm

Pro: Ticks all the boxes

Con: That price tag

This impressively stiff stem is 3D-forged, CNC machined and shot-peened. The process goes some way to explain its relatively high price tag. It’s not just stiff, it’s also crisply finished and even has titanium bolts with oversized M6 heads.  The stack height is modest and the 6° rise can be flipped if you need a lower bar height. Comes with a 10year warranty too. Impressive is the word.

Read review of the Syntace Megaforce 2 stem

best mountain bike stems

KS Ether stem

Light and strong enough for everything from XC to DH

Price: £55.00 | Weight: 121g | Colours: Black | Lengths: 50, 70mm

Pro: A very polished product

Con: Limited length options

KS are much better known for their excellent dropper seatposts but recently they’ve branched out into cockpit components with handlebars and stems. The glossy finish and sheeny ti bolts give this stem a look and feel of premium goods but thankfully the price tag doesn’t follow suit. The wraparound rear clamp designs will please your kneecaps. One niggle: not very many length options currently.

Read review of the KS ether stem

best mountain bike stems

Funn Crossfire stem

There are lighter stems but the Crossfire is hard to beat

Price: £59.99 | Weight: 129g | Colours: Red, orange, blue, black, grey, green | Lengths: 35, 50mm

Pro: The very definition of a modern MTB stem

Con: Sculpted aesthetic won’t suit everyone

The Crossfire cannot be faulted in performance. Very little flex could be perceived during riding even when hauling on the bars. Setting up was simple and despite running all the bolts dry (sorry!) and riding it in desert conditions it never developed a creak. There are plenty of colours to choose from and it has a style suited to any bike. There are slightly lighter stems out there but the Crossfire is hard to beat on every other factor.

Read review of the Funn Crossfire stem

Race Face Turbine R 35 MTB stem

Not cheap but oh-so-good-looking

Pro: Loads of options

Con: On the expensive side

What we really like about the Race Face Turbine R35 is that it’s pretty stiff for a lightweight machined stem. It’s crafted from a lump of 7075 aluminium billet and is oversized in the midriff as well as having an oversized Overbite faceplate. This gets the company’s Top-Lock clamping system, where the top two fasteners are clamped fully, with the bottom two then snugged up to close the gap. This system eliminates uneven clamping and creates a stiffer union between bar and stem. Even with a matching 800mm Next R bar fitted, the steering feels precise and immediate, with just the right amount of resilience.

Read the Race face Turbine R 35 stem review

Renthal Apex stem

Handles the extra twist of wide bars and available down to 31mm

Price: £89.95 | Weight: 110g | Colours: Black/gold | Lengths: 31, 33, 40, 50, 50, 60, 70, 80, 90mm

Pro: Classy and classic

Con: Not the absolute stiffest

Longer-than-standard clamps slide onto the bar’s centre from the taper, and while installation takes a little bit more time, and care needs to be taken on carbon handlebars, once centred, clamp fit is extremely positive. The clamp uses an easier zero-gap design on one side, but with the stem orientated normally (six-degree rise up) the gap is at the top, which isn’t quite as neat when looking down riding the bike. It’s a solid junction, though, and there was no creaking at any point. Function is sorted on the featherweight Apex, but there’s a vague sense it wasn’t the most rigid or precise-steering unit in back-to-back testing. Renthal’s stem is upper end, price-wise, but at 110g it’s the lightest 35mm option here and that helps justify the cost.

Read the review of Renthal Apex stem

USE Ultimate Vyce 35 stem

Really does have a vice-like grip

Price: £89.99 | Weight: 123g | Colours: Black | Lengths: 40, 50mm

Pro: Super solid design

Con: Quirky set-up

Thanks to its high and wide design, the Vyce is pretty damn stiff in use with very little noticeable flex. The internal wedge design goes some way to aiding this without adding too much bulk. And at 123 grams it’s lighter than most 40mm stems. The design does mean the stack height is taller than many competitors, so you will need to play about with spacers to get it in the right position. Plus, the thin aluminium requires the top section to be away from the end of the steerer so you will most probably have to run a spacer on top. The Vyce has its quirks but it’s rolled up in a package that stands out from the crowd of identi-kit stems.

Read review of USE Ultimate Vyce 35 stem

What to look for with the best mountain bike stems

best mountain bike stems

Handlebar and stem clamp diameter

Handlebar diameter is a bit less straightforward. Modern era mountain bikes will either have the more-common 31.8mm diameter handlebars or the newer 35mm diameter handlebars. Older bikes may still be sporting skinny 25.4mm diameter handlebars. Again you can use a tape measure to quickly assess what diameter your bike has. You need to get the same stem clamp diameter as your handlebar diameter ie. 31.8mm clamp stem for a 31.8mm diameter handlebar.

best mountain bike stems

Bolts

4mm and 5mm Allen bolts are most common on mtb stems, with the heavier, larger-diameter bolts typically enabling higher torques and subsequent clamping forces. Cheaper bolts round off more easily, and anodised bolts can lose colour. Stainless steel or titanium bolts maintain looks and are more resistant to corrosion.

best mountain bike stems

Stack height

The vertical real estate the stem demands on the steerer tube. It can be an issue if your fork steerer is too short, and can also relate to the handlebar height achievable and overall stiffness of the stem.

best mountain bike stems

Length

30mm is about as short as you can go on a standard stem. There are some newer designs that enable even shorter stems but they require specially designed handlebars. Stubby stems are something we’re big advocates of here, since reducing the distance the bar extends beyond the steerer will sharpen the steering response, provided your bike is roomy enough. We recommend fitting the shortest stem you can get away with but bear in mind that some older bikes with short top tubes may end up with cramped reach and compromised bike control, in which case we wouldn’t go shorter than 50mm and we’d also think about fitting wider handlebars as a means of widening your reach and improving balance, control and comfort.

best mountain bike stems

Zero gap fastening

More and more stems are now featuring a zero-gap bar clamp design, whereby one pair of clamp bolts fasten fully, and the remaining bolts tighten to lock the bar in place. The design prevents uneven tensioning and reduces the number of bolts you need to fix to a precise torque setting, making set-up easier.

Rise

Rise is the difference in height between the clamps. Most stems are zero-rise, which means if you flip them over they don’t change the bar height. However, a six-degree rise stem allows you to effect a plus or minus six-degree change in bar height by simply turning the stem upside down.

best mountain bike stems

CNC v Forged

Stems are either 3D forged or CNC machined from an aluminium billet (basically a chunk of metal). Forging sees aluminium squeezed under immense pressures into (close to) the stem’s final shape. The technique compresses the material around high stress areas, and it’s argued produces a stiffer product with a better-aligned, denser grain structure. The initial forging cost is expensive and the finish is sometimes less angular, although you do see stems that are forged initially and then tidied up on a CNC machine.