PRO Discover Stem

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.[1]

> Find your nearest dealer here

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.

> How to choose the right stem length

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.

> 9 ways to make your bike more comfortable

[1] 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.

Verdict

Nicely executed beefy stem for playing in the dirt, with handy ports for your cables and wires