If you read and digested our bars and stems grouptest in the September issue of MBR you'll be up to speed on what attributes and design features we look for. So how does Pro Bikegear's short, chunky Tharsis 3Five stack up against our benchmark stems?
Pro Bikegear’s previous Koryak 31.8mm stem was 3D forged and then CNC machined. As the name suggests, the new Tharsis 3Five comes in the bigger 35mm diameter but is only CNC’d, rather than starting with the forging process. Does that make a difference to strength or stiffness?
Obviously forging makes the stem stronger, and you can trim some weight as a result, but in the grand scheme of things the Tharsis is only giving away around 30g to the Koryak. There may be some variance in terms of torsional rigidity if you put both stems on a jig, but I could detect very little difference in terms of steering precision actually on the bike.
The Tharsis is made from a 7050-series grade aluminium, which is slightly tougher and has better corrosion resistance than the alloy used to make the Race Face Turbine tested last month, but the finish is not quite as slick and it’s already showing a bit of wear on the sharp edges.
The Tharsis 3Five does come with a similar zero-gap faceplate, but the difference here is the faceplate is castellated and interlocks into the body of the stem. It’s easy to set-up and I think it looks pretty neat. Pro opts for 4mm fasteners, but they’re also showing a slight amount wear on the faces. Again, this doesn’t affect function, but it’s not something I’d expect so soon on a stem costing £120.
It’s the price of the Tharsis 3Five stem that is the biggest change from the original £60 Koryak model and also my main criticism. While the 35mm clamp size is arguably an upgrade, I’m not convinced you’re getting that much extra for twice the price.