Bontrager XXX Stem 7 Degree

Bontrager's XXX Stem is from the top end of its range and is fully constructed from carbon fibre. It's expensive, but with plenty of neat design cues, top notch finishing and solid ride qualities, it could be the perfect finishing touch for your pride and joy.

A carbon fibre stem is often seen as a bit of an extravagance, especially when you consider that the weight and cost are normally on the high side compared with their aluminium alloy counterparts. Going the non-metallic route does have its benefits though. First, the carbon fibre can be laid up to promote particular performance qualities; secondly, it's easier to create less uniform shapes with the black cloth...

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The XXX has a rectangular central profile, which Bontrager claims "increases torsional stiffness and vertical compliance". It certainly feels stiff when you're really grabbing on the handlebar when climbing or sprinting, but also has that little bit of bounce to take out any road vibrations. As far as shape goes, the chunky, slab-sided style of the XXX stem means it suits a lot of the new aero and oversized framesets on the market.

The XXX is available in eight sizes from 60mm through to 130mm but only one angle option, +/- 7°. There are two colour options – either black or this high gloss white version, which looks pretty bling, but the paint does chip quite easily.

The XXX is designed for use with 1 1/8in steerer tubes and is compatible with both alloy and carbon fibre. The finish is top notch in this area, with all edges and faces perfectly smooth.

When it comes to clamping, the XXX doesn't go down the usual route – bolts from one half tightening into a threaded section on the other. Instead, the Bontrager uses two long barrel nuts, one either side of the rear-facing slot. One is threaded, the other isn't, which means when you are tightening things up, the load is being spread evenly over the entire clamping area rather than just where the usual bolts are. It's meant to be a safer option for carbon fibre.

The XXX Stem is designed to be used with oversized 31.8mm diameter handlebars. You get two narrow faceplates, both of which are marked for handlebar alignment. All the hardware used for clamping is steel, which I think is good to see, as a lot of high-end stems use titanium to save weight but you often sacrifice durability.

The use of those two faceplates means the XXX is compatible with Bontrager's Blendr system – a clip setup that locates between the inside face of the stem and the outer face of the handlebar giving you an out-front mount for a GPS, light or bike computer. It's a great idea as the stem body itself doesn't work well with the likes of Garmin mounts.

I mentioned the high price and weight, and these are probably its only weaknesses. At 182g (130mm length) it isn't exactly heavy, but we've seen plenty of 30 to 40 quid stems around 30g lighter.

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Value is always a bit of tough one with components like this. Chances are, if you are thinking about buying a carbon fibre stem, cost effectiveness probably isn't that high up your list of priorities. Compared with other full-carbon stems on the market, there are some cheaper and some much more expensive, but looking at the very good quality and finish of the XXX, I'd say the price is about right for its market place.

Overall, the XXX Stem looks cool and feels good when you're riding. There is some flex there providing a bit of comfort without affecting the overall stiffness, and thanks to the material lay-up you get a smooth, solid ride. Ultimately, though, for me, it doesn't quite do enough to justify the price outlay when compared with alloy stem options.

Verdict

Stiff and comfortable carbon stem with a well-thought-out design, but it is heavy and pricey