WTB have a super long history of building MTB wheels and rims, but they’re relatively new to the gravel space. These WTB Proterra Light i25 wheels borrow a lot of MTB DNA to create a tough, responsive option for the fat tire, smaller diameter wheel-curious crowd. They’re currently being offered at half price as well which makes them reasonable value.
Design and construction
The Proterra Light i25 rims use a 17.5mm deep open cavity design with pronounced ‘On Ramp’ profiling of the 25mm wide (below the hooks) extrusion. The rim is lined with a protective ‘Solid Strip’ under the rim tape to reduce the chance of it getting punctured with a tyre lever or a spoke snapping and pushing through from inside. Tubeless valves are supplied as standard too. The i25 is only available in 650B though, with the i23 occupying the 700c space.
28 spokes each end are double-butted conventional J-bend style hooking into retro-looking windowed flanges with subtle graphic detailing on the hub bodies. The freehub uses an offset 6-pawl design to give very fast 3.7-degree engagement and comes in Shimano HG or SRAM XDR options. The front hub end caps are switchable too, though WTB only offer 12mm in the apparently American built wheels.
At 1,740g they're an OK weight rather than actually 'Light' so you’re not gaining any advantage on the scales by switching to 650B. The smaller diameter means less leverage though and combined with the fast reacting hub, the Proterras are an encouragingly peppy wheel to ride. They also have a nicely sprung feel which flatters the extra cushioning and buoyancy you can get by running larger volume tires at really low pressures. The pronounced ‘On Ramp’ profile keeps tires well seated too so I had zero burp or unhooking issues when paired with WTBs 47mm Sendero tires as low as 18psi during testing. Despite regular rim thumps on rocks and roots, the rims didn’t dent or otherwise damage either.
The ‘on ramp’ does make tires more of a fight to get on and off through so have your bigger tire levers ready or get down the thumb gym for a warm up before working on them. The freehub is pretty vocal too if that’s something that bothers you, but I had zero bearing or grease weep issues despite putting plenty of miles into them.
WTB’s Proterra Light i25 are certainly worth a look if you’re smaller wheel / bigger tire curious, as their toughness and width brings out the best of road/gravel ‘plus’ tech. The responsive hub hides their sturdy build well too and while they’re being sold for half price they’re decent value too.
Tech specs: WTB Proterra Light i25 wheels
- Price: $714.90 (pair)
- Sizes: 650b only
- Options: 12mm or 15mm front hub caps
- Weight: 800g front + 940g rear = 1740g (including valves)