The Pro Vibe 7S Stem is undoubtedly the stiffest I have used, but is also impressively low in weight. The 'Puzzle' clamping system also works very well and is simple to fit and adjust.
It isn't until you use a truly stiff stem that you notice how much variation you can get. This is genuinely the stiffest stem I have ever used; there is no give whatsoever, even when I was actively trying to get some. It makes it fantastic for sprinting and climbing, although I'm not sure it would be too much fun on cobbles.
The first place to start is with the initial fitting of the stem: it's considerably easier than others I have used thanks to the Puzzle clamp system. The stem has two bolts rather than four, with the top of the faceplate connecting to the main body of the stem and securing the bar (I tested it with the matching Pro Vibe 7S bar, reviewed here). It also has a brushed aluminium design that looks like two interconnecting Vs, which I think looks really good. It has a standard 31.8mm diameter clamp, which was easy to fit around the bar.
At the back it has a traditional clamping system around the steerer tube, with two decent quality bolts that didn't thread or rust at all despite being used in some soaking conditions.
The stem is made from a 3D forged 7075-T6 alloy, which keeps the weight down to 137g for the 110mm model tested. This is very good for an aluminium stem, with many carbon stems also sitting around this figure. It's hardly surprising, given that it's the same stem used by Chris Froome in last year's Tour de France – Sky's marginal gains wouldn't have stood for anything else.
This low weight doesn't impact at all on the stem's stiffness; as I've said (twice already!), it's undoubtedly the stiffest I have used. There was absolutely no movement either side-to-side or up and down regardless of what I tried. It was great for climbing and sprinting in the drops, but did mean that spending longer periods on rough roads was slightly more uncomfortable – a sacrifice worth making, I reckon.
In terms of looks (which, if Chris Froome is staring at it for hours on end, is going to be important) the version I tried was the Team Sky model with a big blue stripe running down its length. This isn't what I would choose, but the stem is available in a more discreet black and white. It comes in 10mm increments from 80-140mm, each with a -10 degree angle.
As you might expect of a stem used by Team Sky it doesn't come cheap, but at £79.99 it compares well with other similar ones out there. The FSA SL-K, which Liam tested a couple of years ago, is £84.95 but around 25g heavier, while the Deda Superleggero, also tested on road.cc a couple of years ago, by Stu, is about £35 more but only around 10g lighter. When you get to that level of weight loss you are looking at breaking the £1 for every gram lost rule, but if you're a weight weenie then this may well work for you.
Overall, I really like this stem. It's incredibly stiff and brilliant for sprints and climbs, although prolonged use on rough roads might call for you to put some extra padding on your bar and mitts. It is priced around the same as its major competitors and has some neat design features, like the Puzzle clamp, which make it look cool on the bike and function well during adjustment and fitting.
Really stiff and responsive – I can see why Chris Froome spends so long staring at it
road.cc test report
Make and model: Pro Vibe 7S Stem
Size tested: 110mm
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?
A high quality stem aimed at those who are looking to emulate Team Sky or who just want a high quality piece of kit.
Pro says: 'High performance lightweight oversized alloy 7075-T6 stem as used by top professional riders.'
I would say that it fits these parameters well, being stiff and robust.
Tell us some more about the technical aspects of the product?
3D forged 7075-T6 alloy construction increases strength and keeps the weight down
Innovative and secure Puzzle clamp system evenly spreads load through the clamp area whilst reducing stem weight
The Gapless puzzle clamps interlocking design makes side movement loading impossible where traditional top bolts would be under high stress
Wide bolt spacing and forged alloy faceplate further secures and stiffens clamp interface
Triangular design gives optimal stiffness to weight ratio
Oversized 31.8mm clamp diameter further reduces unwanted flex under high load by increasing strength and stiffness
Angle: -10 degrees
For 1-1/8 inch diameter steerer tubes
Average weight 120 grams for 110mm length
Extremely well made, with the alloy 7075-T6 being a very good choice.
Brilliant performance, no kind of flex or twist whatsoever.
Seems very well made and the bolts didn't thread or rust at all.
Perhaps not the most comfortable for overly rough roads, but not too bad all things considered.
It's expensive, but you very much get what you pay for.
Tell us how the product performed overall when used for its designed purpose
Very well, I was particularly impressed by the stiffness and lack of flex and twist.
Tell us what you particularly liked about the product
Quality of construction is fantastic which shows through the solidity of the handlebar grip.
Tell us what you particularly disliked about the product
Perhaps a bit too stiff if you are trying to use it on rough roads over several hours.
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
Very stiff and allows for a very responsive ride. I can understand why Team Sky use this stem.
About the tester
I usually ride: Cannondale Supersix Evo 6 My best bike is:
I've been riding for: 5-10 years I ride: Every day I would class myself as: Experienced
I regularly do the following types of riding: commuting, club rides, sportives, general fitness riding, fixed/singlespeed, mountain biking
George spends his days flitting between writing about data, running business magazines and writing about sports technology. The latter gave him the impetus (excuse) to get even further into the cycling world before taking the dive and starting his own cycling sites and writing for Road.cc.
When he is not writing about cycling, he is either out on his bike cursing not living in the countryside or boring anybody who will listen about the latest pro peloton/cycling tech/cycling infrastructure projects.