At road.cc every product is thoroughly tested for as long as it takes to get a proper insight into how well it works. Our reviewers are experienced cyclists that we trust to be objective. While we strive to ensure that opinions expressed are backed up by facts, reviews are by their nature an informed opinion, not a definitive verdict. We don't intentionally try to break anything (except locks) but we do try to look for weak points in any design. The overall score is not just an average of the other scores: it reflects both a product's function and value – with value determined by how a product compares with items of similar spec, quality, and price.
Good scores are more common than bad, because fortunately good products are more common than bad.
This incarnation of the Pro Vibe Di Stem focuses on aerodynamics and the latest technology used in electronic gear systems to turn your bike into a smooth-looking, wind-cheating work of art. Form is backed up by function, with a component that excels in stiffness without carrying any extra weight.
We took a look at the Pro Vibe 7S stem last year and were mightily impressed, so it's great to see that the engineers at Pro haven't meddled with its performance at all.
This new Vibe is unbelievably solid in use but without giving any feeling of harshness over rough surfaces. The differences in comfort levels and reduced road buzz are pretty marginal compared with most other aluminium alloy stems, but still noticeable.
The front end has some bulk to it, to resist those forces transferred from the handlebar when you are really going for it in a sprint, for instance, or heavy braking and steering on a steep technical descent. The rest of it is reasonably svelte though, and I especially like the octagonal style shape with its black-on-black logos.
The front clamp has gone back to a four-bolt design, although the holes have been moved to the rear to keep them out of the airflow. The benefits will be minimal, it's not something you're going to notice in the real world, but it does look smart.
To make setup and adjustment easier, the bolt holes are threaded into the faceplate at an angle. The trouble is, the hex keys on most multi-tools won't be long enough to prevent you fouling the stem body. This can make roadside tweaks a pain.
The Vibe is designed to be paired with the carbon fibre aero handlebar of the same name, which I've also reviewed, with both being aimed predominantly at the Shimano Di2 electronic shifting market. Pro being Shimano's component arm, it's no surprise that there's collaboration between the two.
The Vibe handlebar has an exit hole at the rear which allows the battery cable to travel from the bar, through the stem body, and out of the hole you see above the steerer clamp in the photo. This means that if you use a fork steerer-mounted Di2 battery, everything is hidden from view.
A quirky shaped top cap (not shown) keeps the lines smooth over the top of the cable but this obviously means that it'll only work if your steerer is cut short. There is the option of leaving the steerer longer, poking out above the stem, but you will require a special spacer.
Weight-wise it's not in the same league as Deda's more expensive Superleggero at 124g or the Superlight from Aerozine at less than half the price and 40g lighter, but the Vibe certainly feels hefty and I'd rather have the stiffness anyway.
For £99.99 the Pro is at the more expensive end of the alloy stem market, but I wouldn't really say it's overpriced. It's a very good piece of kit and you'll find it adorning plenty of pro bikes in the peloton so it can't be bad.
With or without the matching Vibe bar, this stem is a good choice for those riders who want a reasonably light but very stiff stem.
Super-stiff peloton-proven performance with added neat aero tweaks for Di2 users
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road.cc test report
Make and model: Pro Vibe Di2 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?
Pro says: "The Pro Vibe Stem is designed to align your cockpit perfectly with your bike for an optimal riding position. Supreme stiffness offers you more control during those high-speed descents or manoeuvres. It's constructed of a 3D forged 7075-T6 alloy that is incredibly strong whilst also keeping the weight down. A gapless head lock clamp design makes side movement under load impossible where traditional top bolts would be under high stress. Wide bolt spacing and the forged alloy faceplate further secures and stiffens the clamp interface. The triangular design also gives an optimal stiffness to weight ratio. An oversized 31.8 mm clamp diameter further reduces unwanted flex under high load by increasing strength and stiffness. The Vibe Stem has been developed for ultimate integration with Di2 to give you maximum aerodynamic performance and ultra-clean styling. With the specially positioned cable ports you can internally route the Shimano Di2 cables. No visible cables, all of its features. The innovative angled reverse bolts remain easy to access whilst drastically reducing drag. The Pro Vibe Stem is a high performance lightweight stem as used by top professional riders."
The Vibe is a top quality race stem with plenty of design highlights and impressive stiffness.
Tell us some more about the technical aspects of the product?
3D Forged Anodized 7075-T6 Alloy Construction
Gapless Head Lock Clamp Design
Forged Alloy Faceplate
31.8mm Clamp Diameter
Internal Routing for Di2 Cables
Wide Bolt Spacing
Lightweight, Angled Reverse Titanium Bolts
Angle: -10 or -17 degrees
Length: 80mm to 140mm in 10mm increments
Tell us how the product performed overall when used for its designed purpose
At its most basic job of 'being a stem', the Vibe offers brilliant performance. Add in the aero details and cable routing tweaks and the Vibe is pretty darn good.
Tell us what you particularly liked about the product
Brilliantly stiff for full-on efforts.
Tell us what you particularly disliked about the product
I haven't got Di2 to take advantage of that cable hole.
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 Vibe is a fantastic stem for those riders who are really looking for stiffness; when paired with the Vibe bar it's hard to beat.
About the tester
I usually ride: This month's test bike My best bike is: Kinesis Aithein
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
With 20 years of road cycling and over 150,000 miles in his legs it's safe to say Stu is happiest when on the bike whatever the weather. Since writing his first review for road.cc back in 2009 he has also had a career in engineering including 3D-CAD design and product development, so has a real passion for all of the latest technology coming through in the industry but is also a sucker for a classic steel frame, skinny tyres, rim brakes and a damn good paintjob.
His fascination with gravel bikes is getting out of control too!