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Verdict: 
Stiff and comfortable carbon stem with a well-thought-out design, but it is heavy and pricey
Weight: 
182g
Bontrager XXX Stem 7 Degree
7 10

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...

> Find your nearest dealer here

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.

Bontrager XXX Stem 7 Degree 3.jpg

Bontrager XXX Stem 7 Degree 3.jpg

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.

Bontrager XXX Stem 7 Degree 2.jpg

Bontrager XXX Stem 7 Degree 2.jpg

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.

> Find more road.cc reviews of stems here

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

road.cc test report

Make and model: Bontrager XXX Stem 7 Degree

Size tested: White

Tell us what the product is for, and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about it?

Bontrager says: "The XXX Stem is still our lightest carbon fiber stem, but it's been redesigned with the new CnD shape profile for a more controlled and forgiving ride experience, providing you with consistent comfort to the Nth degree."

Tell us some more about the technical aspects of the product?

From Trek's website:

Seamless accessory integration with Blendr XXX

CnD shape profile increases torsional stiffness and vertical compliance

Double-barrel, single-bolt (M6) system clamps evenly and conveniently

4-bolt dual band clamp securely holds handlebar

Uses high-quality M5 titanium faceplate bolts with 5.2Nm torque spec

Safe for use with carbon and alloy steerer tubes and handlebars

Suitable for road or mountain use

60mm - 130mm length options

Rate the product for quality of construction:
 
8/10
Rate the product for performance:
 
8/10
Rate the product for durability:
 
8/10
Rate the product for weight (if applicable)
 
6/10

Not too bad for a full carbon fibre stem, but heavier than a lot of alloy ones that are much, much cheaper.

Rate the product for comfort (if applicable)
 
8/10
Rate the product for value:
 
5/10

Sits somewhere in the middle for a full carbon fibre stem.

Tell us how the product performed overall when used for its designed purpose

It is very stiff yet forgiving. Accessory bundle is a nice touch too.

Tell us what you particularly liked about the product

Its design.

Tell us what you particularly disliked about the product

Paint on the white version chips easily.

Did you enjoy using the product? Yes

Would you consider buying the product? Yes

Would you recommend the product to a friend? Yes

Use this box to explain your score

The Bontrager XXX Stem offers stiffness without being uncomfortable. It performs well and feels very solid. There are some clever design features too, but it is expensive and quite heavy compared with a lot of alloy models.

Overall rating: 7/10

About the tester

Age: 37  Height: 180cm  Weight: 76kg

I usually ride: This month's test bike  My best bike is: Mason Definition

I've been riding for: 10-20 years  I ride: Every day  I would class myself as: Expert

I regularly do the following types of riding: time trialling, commuting, club rides, sportives, fixed/singlespeed

Stu knocked out his first road.cc review back in 2009 and since then he's chucked the best part of seventy test bikes around the West Country, a couple of them quite literally! With three alloy and two steel bikes in his fleet he's definitely a metal man (that'll be the engineering background) but is slowly warming to that modern carbon fibre stuff along with fat tyres & disc brakes.
It's not all nostalgia though, after spending the last few years in product design Stu keeps banging on about how 3D printing is going to be the next big thing and he's a sucker for a beautiful paint job too.