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Verdict: 
Really stiff and responsive – I can see why Chris Froome spends so long staring at it
Weight: 
137g
Pro Vibe 7S Stem
9 10

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.

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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.

Pro Vibe 7S Stem 3.jpg

Pro Vibe 7S Stem 3.jpg

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.

> Check out more reviews of stems on road.cc here

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.

Verdict

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

Rate the product for quality of construction:
 
9/10

Extremely well made, with the alloy 7075-T6 being a very good choice.

Rate the product for performance:
 
9/10

Brilliant performance, no kind of flex or twist whatsoever.

Rate the product for durability:
 
8/10

Seems very well made and the bolts didn't thread or rust at all.

Rate the product for weight (if applicable)
 
9/10
Rate the product for comfort (if applicable)
 
7/10

Perhaps not the most comfortable for overly rough roads, but not too bad all things considered.

Rate the product for value:
 
5/10

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.

Overall rating: 9/10

About the tester

Age: 27  Height: 6 ft  Weight:

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.  

9 comments

Avatar
Bobbinogs [251 posts] 1 year ago
0 likes

I have tried many different stems and, besides the effects of length, etc., I have not been able to detect any difference whatsoever between brands/models, whereas a 10 PSI drop on the front tyre is instantly noticeable. Maybe I am lucky or unlucky, no idea!

Avatar
DrJDog [413 posts] 1 year ago
0 likes

I had no idea my stem wasn't responsive enough!

Avatar
shay cycles [389 posts] 1 year ago
1 like

It's a stem.

Talk about strength and weight if you must.

Talk about appearance if you must.

Talk about durability of you must.

But it is a lump of metal that connects the bars to the steerer.

The forks, steerer, bars, front wheel, tyre and the stem work together to steer the bike.

So please spare us the waffle about responsiveness!

Avatar
. . [175 posts] 1 year ago
0 likes

So why no picture of the marvellous Puzzle clamp?

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alexb [162 posts] 1 year ago
1 like

So I don't get this obsession with weight/price ratios.

The Deda Zero One is a perfectly decent stem, widely available for about £16, weighs 133g in 110mm length - or 4g less than this stem for a saving of over £60.

I have no idea whether it's stiffer or not, since this is something I don't see "tested" very often. It's a very subjective judgement unless it's backed up with actual test data anyway.

What I see is a stem in Sky colours, that can only be mounted one way up, with an overly complex, but quite clever clamp that's not very light, but is apparently very stiff.

Can you get in a colour scheme that doesn't match your least favourite satellite TV brand?

Avatar
unconstituted [2341 posts] 1 year ago
1 like
alexb wrote:

So I don't get this obsession with weight/price ratios. The Deda Zero One is a perfectly decent stem, widely available for about £16, weighs 133g in 110mm length - or 4g less than this stem for a saving of over £60. I have no idea whether it's stiffer or not, since this is something I don't see "tested" very often. It's a very subjective judgement unless it's backed up with actual test data anyway. What I see is a stem in Sky colours, that can only be mounted one way up, with an overly complex, but quite clever clamp that's not very light, but is apparently very stiff. Can you get in a colour scheme that doesn't match your least favourite satellite TV brand?

 

Deflection can be tested and you'll see some sites doing it occassionally. Would be amazing to have a cycling site that really tested stuff instead of saying, 'this is the stiffest ever, this is the fastest ever' etc. 

http://blog.fairwheelbikes.com/reviews-and-testing/stem-review/

Avatar
Bobbinogs [251 posts] 1 year ago
0 likes
alexb wrote:

... Can you get in a colour scheme that doesn't match your least favourite satellite TV brand?

Yes, from the article posted above:

"...the stem is available in a more discreet black and white"

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cyclisto [223 posts] 1 year ago
0 likes

I find cheap Uno and Deda stems without any significant flex. Maybe only very strong riders such as pros who use 130mm+ stems on undersized frames may receive some traces of flex.

Avatar
Anthony.C [232 posts] 1 year ago
0 likes

I read a review from someone whose Deda Zero stem snapped at the faceplate..it put me off, I bought the more expensive Deda stem.