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.
The Discover stem from Shimano's component offshoot PRO Bike Gear is a sturdy, tidily made unit that does a capable job of connecting your handlebar with your steerer. Aside from visually matching PRO's other gravel bike parts it's unremarkable, but a very competent job nevertheless.
The most significant features of the PRO Discover stem are the 7075 aluminium alloy it's made from and the handy hole by the steerer clamp for your cables. It's fitting that a Japanese company should be using 7075 aluminium as this blend of aluminium, zinc, magnesium and copper was originally developed in secret by a Japanese company, Sumitomo Metal, way back in 1935. It's still one of the strongest aluminium alloys around (its tensile strength is 572 Mpa, almost twice the 290 MPa of 6061 aluminium), and therefore a very sensible material for a critical component like a stem.
To help keep your handlebar area tidy, PRO has given you a little hole through which to route your cables and Di2 wires so they can pass through the interior of the matching Discover handlebar. If not having cables flapping in the breeze makes you happy then this is a nice feature to have.
The PRO Discover stem is held in place by 4mm steel bolts, two on the steerer clamp, four holding on the faceplate. Pet peeve KLAXON: the steerer bolts face in opposite directions, so to tighten the damn thing you have to switch sides instead of just moving your hex key up a couple of centimetres.
Oddly, the extension is six degrees from a right angle. For me at least, I want the drops on a gravel bike about where the hoods are on a road bike, and a rise of just six degrees doesn't lift them very much. It'd be nice if PRO offered some other options too, like 15 degrees or even 25 degrees. That'd give PRO a second market too: very flexible speed demons who want a very low position.
In use you just don't notice the Discover stem, which is the way it should be. You turn your handlebar, the Discover stem turns your steerer and, er, that's it.
You've got an awful lot of choice when it comes to handlebar stems, so how does the PRO Discover stack up?
This isn't the stem to buy if weight matters to you. At 161g in a 100mm length it's up there with famously beefy stems like the Thomson X4; it's not far off twice the weight of an Extralite Hyperstem, though it's also half the price.
But weight clearly isn't what the PRO Discover is all about. This is a seriously sturdy stem made from the strongest aluminium alloy in widespread use, and therefore a deeply reassuring thing to have connecting your handlebar to your stem.
Given that it's £70, sceptics are going to say that this is yet another example of things being more expensive because gravel, and there's perhaps some truth in that. But if you're barrelling down a steep forest road at 40mph you might feel the reassurance of this beefy beast is well worth having.
 To head off a deluge of comments from people who know more about materials science than me (not hard), yes I know ultimate tensile strength isn't the only property that matters here. A component designer will take into account yield strength, elongation at yield, corrosion resistance and a raft of other properties. Nevertheless it's reassuring that this stem isn't much lighter than some 6061 stems but is made from a far stronger material.
Nicely executed beefy stem for playing in the dirt, with handy ports for your cables and wires
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road.cc test report
Make and model: PRO Discover Stem
Size tested: 100mm
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?
It's a sturdy forged and machined stem in 7075 aluminium alloy. Graphics and logo are a visual match with PRO's other Discover gravel-bike components, but there's really nothing else that makes it a gravel-specific stem.
Tell us some more about the technical aspects of the product?
3D FORGED & CNC MACHINED AL 7075
PERFECT MATCH WITH DI2
FOR 1 1/8' STEERER TUBES
WEIGHT: FROM 142 GRAMS
ANGLE: 6 DEGR. (FLIP FLOP)
LENGTHS: 70-110 MM
Impossible to be sure after a few weeks of use, but the heft and materials choices here suggest serious durability, so I'm sticking my neck out and giving it 9/10. I'm going to look pretty silly if it breaks next week, but given that'll land me on my face I'll look pretty silly anyway.
Lots of stems are lighter. If weight's of paramount importance to you, don't buy this one.
For £70 it's competitive with beefy stems like the Thomson X4 (RRP £80) but there are plenty of good quality aluminium stems on the market for less.
Tell us how the product performed overall when used for its designed purpose
Perfectly well as far as it goes, but I'd like a bit more rise please.
Tell us what you particularly liked about the product
Understated looks, general beefiness.
Tell us what you particularly disliked about the product
Dear stem manufacturers: stop pointing the bloody steerer clamp bolts in opposite directions.
How does the price compare to that of similar products in the market, including ones recently tested on road.cc?
Arguably it's a shade spendy. The Genetic STV, also made from 7075 aluminium, is £50, while PRO's own LT stem is just £35, albeit in 6061 aluminium.
Did you enjoy using the product? It certainly didn't detract from my enjoyment of riding my bike.
Would you consider buying the product? No, I'd want more rise than offered here.
Would you recommend the product to a friend? Yes, if it met their requirements.
Use this box to explain your overall score
This is a good general-purpose stem, with a bit of extra beef for off-road use. The holes for cables and Di2 wires are nice to have and it's all tidily done. It's not exceptional in any department, it's just... good, so 3.5/5.
About the tester
I usually ride: Scapin Style My best bike is:
I've been riding for: Over 20 years I ride: Most days I would class myself as: Expert
I regularly do the following types of riding: commuting, touring, club rides, general fitness riding, mtb,
John has been writing about bikes and cycling for over 30 years since discovering that people were mug enough to pay him for it rather than expecting him to do an honest day's work.
He was heavily involved in the mountain bike boom of the late 1980s as a racer, team manager and race promoter, and that led to writing for Mountain Biking UK magazine shortly after its inception. He got the gig by phoning up the editor and telling him the magazine was rubbish and he could do better. Rather than telling him to get lost, MBUK editor Tym Manley called John’s bluff and the rest is history.
Since then he has worked on MTB Pro magazine and was editor of Maximum Mountain Bike and Australian Mountain Bike magazines, before switching to the web in 2000 to work for CyclingNews.com. Along with road.cc founder Tony Farelly, John was on the launch team for BikeRadar.com and subsequently became editor in chief of Future Publishing’s group of cycling magazines and websites, including Cycling Plus, MBUK, What Mountain Bike and Procycling.
John has also written for Cyclist magazine, edited the BikeMagic website and was founding editor of TotalWomensCycling.com before handing over to someone far more representative of the site's main audience.
He joined road.cc in 2013. He lives in Cambridge where the lack of hills is more than made up for by the headwinds.