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?
With no moving parts and a simple function, even the very best mountain bike stems have a modest effect on the performance of your bike. But 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.
Best mountain bike stems
- Race Face Turbine R 35 – WINNER
- E*thirteen Base – BEST VALUE
- Syntace Megaforce 2
- KS Ether
- Funn Crossfire
- DMR Defy 35
How we tested the best mountain bike stems
With plenty of stems to evaluate, we initially spread them between a mix of test bikes and trusted testers to put the early miles in and assess long-term durability. The testing process was topped off with a final round of back-to-back analysis on our test track.
The stems were tested on a Giant Reign with a 800mm Spank Spike Vibrocore handlebar and an aluminium Renthal Fatbar, also at 800mm, to generate maximum leverage an torsional forces. The first track blended man-made g-out berms with technical, twisty, rock gardens that demanded plenty of body language to stabilise the bike. All bolts were greased as necessary, and tightened to the recommended torque settings using a torque wrench.
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Race Face Turbine R 35
Pro: Loads of options
Con: On the expensive side
With a rainbow palette of anodised colours, the Race Face Turbine R stem indulges your creative side. Whether you choose to go mild or wild, the sturdy forged and CNC’d body is stiff enough for the widest of bars and burliest of builds and even comes in a stubby 32mm length if you’re looking for a truly direct steering response.
Its gapless clamp holds bars securely and spreads loads evenly, while the rounded-off edges of the steerer clamp keep the opposing bolts away from your knees.
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.
E*Thirteen Base 35
Prie: £45 | Weight: 155g | Colours: Black | Lengths: 40, 50mm
Pro: Does everything you need for minimal cash
Con: Not as blingy as some
Top value for a stiff, good-looking stem available in stumpy 40mm and 50mm lengths, the e*thirteen Base really impressed us with its function and detailing.
Opposing stem bolts with T25 heads are just one such feature, while the gapless faceplate is something normally reserved for much pricier models. Suitable for 35mm bars, this is a great option if you’re looking for a snappier cockpit without breaking the bank.
Function is brought to the fore with this excellent e*thirteen Base stem. It comes with opposing stem bolts, that are nicely recessed to keep them away from knees, and use T25 fasteners for less chance of rounding.
The gapless face plate means you cinch down the top bolts until the gap disappears, then torque the lower bolts to the recommended setting. It’s easier to install and it more evenly spread the loads. The bar is held by a wide clamp and all the edges are softly rounded off. An excellent stem at a great price.
Syntace Megaforce 2
Price: €118.00 | Weight: 105g | Colours: Black | Lengths: 30, 40, 50, 60, 70, 80mm
Pro: Ticks all the boxes. Incredible stiffness
Con: That price tag. Incredible stiffness
All of the expense of this wonder stem is totally hidden. The money goes into the manufacturing process. The stem is made via a process called 3D-forging which is essentially pushing non-liquid aluminium through a die under insane amounts of pressure. You can’t see the benefit with the naked eye but essentially the resulting product is stronger and stiffer and has no stress riser points.
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. Yep, these bolts are made form titanium and have a torque setting of 8Nm (most stems’ bolts are 5-6Nm) which further highlights how strong this stem is.
The stack height is modest and the 6° rise can be flipped if you need a lower bar height. Comes with a 10 year warranty too. Impressive is the word.
Light and strong for everything
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 titanium bolts give this stem a look and feel of premium goods but thankfully the price tag doesn’t follow suit. Even though the stem is designed and marketed at enduro racers it doesn’t feel the need to add the usual ‘enduro tax’ on to the price tag. Kudos to KS.
The wraparound rear clamp designs will please your kneecaps.The offset clamp does make it slightly more fiddly to access the bolts when tightening them up (Allen keys on multitools will particularly struggle to do more than a half-turn at a time) but then again, how often do you ever touch your stem bolts? It’s a niggle and nothing more. Your knee caps are more important so we reckon the wraparound design is this stems’ USP and not its Achilles heel.
One niggle: not very many length options currently. This is the main problem we have with this stem is its limited length options. KS really need to offer this stem in sub-50mm lengths. 35mm is pretty much the standard on enduro race bikes these days. having said that, if you’re tall enough – or your bike just plain works better with 5omm stems – there’s plenty here to recommend the KS Ether as a killer choice.
Offers a different style
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
Funn are a brand to go to when you’re a bit bored of the trad brands and boring black, squared-off everyman safe anti-style. Funn stuff has a definite aesthetic and vibe to it. That aesthetic is one of flowing lines and organic pseudo-muscly shapes. Truth be told, not everyone digs this look but if you do, we can safely say that this stem is really, really good from a performance point of view as well.
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.
One thing to note is that the Crossfire is a zero rise stem, even though from some angles it doesn’t look like it is. It’s the lower offset gap that creates this optical illusion. This off-set gap is a deliberate design to ensure there’s more material directly under the vertical plane of the forces coming from the handlebar above. Whether this is true is debatable but we do reckon it helps ward off annoying creaks if nothing else.
DMR Defy 35
A rare short stem with rise
Price: £55.00 | Weight: 174g | Colours: Black, silver | Lengths: 35mm
Pro: Super secure. Raises your front end whilst having low stack height. Good price.
Con: Typically robust weight. Square edge aesthetic may not suit some bikes.
The Defy stem is designed to be perfect match (aesthetically speaking) to DMR’s own Wingbar but has a few features that make it a very attractive package for any cockpit combination.
Twin face plate clamps use a Top-Close clamp design where you tighten both top bolts until they touch the stem body before tightening the lower bolts, ensuring simple, safe and effective bar installation. The two-piece design does make things slightly fiddlier in installation (there are two face plates to keep an eye rather than one) but once installed they do look really cool and very modern.
The 6061 aluminium Defy has a shape that trims down the steerer clamp stack height to create one of lowest on the market. At just 28mm this makes the Defy perfect if you want to play a little more with stem/bar height (and thus you bike’s effective reach distance) or have a fork with a less than ideal steerer length. We had to add more spacers to take up the excess steerer.
One of the best – and pretty unique – aspects of the Defy stem is that it’s a stubby 35mm length stem that also packs in a bit of rise (at least 5mm), which is really handy if you want to raise your bar height without resorting to stem spacers or a new handlebar.
Sure, this stem is not going to win any weight weenie competitions but it’s crisply made, stiff as heck, offers a rare bit of rise for a dinky stem and, always importantly, has plenty of style whilst doing so.
What to look for with the best mountain bike stems
A mountain bike stem connects the handlebars to the fork steerer. They come in different lengths and different rises, allowing you to tune your cockpit position Modern stems are typically under 70mm in length, with 40mm and 50mm being the most popular measurements. Generally there are twin bolts to clamp around the steerer tube, and four bolts at the face plate to attach the handlebar.
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 or vernier calipers 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. You’ll also need to check the handlebar diameter. This will either be 31.8mm or 35mm on modern mountain bikes. Make sure you measure the area at the clamp, not the ends at the grips.
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.
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.
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.
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.
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 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.
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.