RoadPlus gathers momentum as WTB launches 650b Horizon tyre

There have many technological developments in road cycling over the past few years, and keeping up with them all can be a tricky task. One trend that has emerged and one that many cyclists seem keen on, is the shift towards a wider tyre. Our roads aren’t getting any smoother, and bigger volume tyres provide a smoother ride. 

WTB has just unveiled its new Horizon, a 47mm wide tyre for a 650b rim. It’s decided to go with RoadPlus as a way of categorising this new tyre, but it’s not doing anything new here; a lot of people in the industry that we’ve spoken to have been speculating on the rise of RoadPlus for some time

- Is 650b the future for road bikes? road.cc investigates

Where does RoadPlus fit in?  Endurance bikes accommodate up to 28mm tyres and gravel/adventure bikes go up to about 35-40mm, on the same 700c rim. You can only increase the size of the tyre on the same rim size so far until you eventually encounter issues with geometry and clearance. However,  decrease the size of the wheel and you can fit a bigger tyre while retaining the desired geometry. 

- First ride: Cannondale Slate

That’s the thinking behind the bold new Cannondale Slate, which rides on 42mm tyres shod onto 650b rims, while retaining pretty conventional road bike geometry. The smaller frame builders have also been exploring RoadPlus, with Richard Hallett talking us through his reasons for using 650b wheels on his latest steel road touring bike. 

Anyway, back to WTB’s new tyre. The US company says the Horizon Road Plus tyre “brings supple plus-size traction and smooth riding characteristics beyond where the pavement ends. Ride it on tarmac, take it to the dirt as well,” providing an indication of the riding potential it has in mind for the fat rubber. 

The tyre is 47mm wide and fits into any frame that can take a regular 28-30mm tyre, so that’s some endurance bikes and most adventure bikes. You could also fit it to a cyclocross bike. It has a list of compatible bikes here.

- Why you need to switch to wider tyres

The tyre has a smooth centre section and a herringbone tread pattern on the sides with “cornering channels”. It has a claimed weight of 415g. Oh, and it’s tubeless-ready as well. The Horizon tyre will cost  $67.95 and be available in July this year. The tyre is being launched at NAHBS this weekend so we'll hopefully get some more information after the show.

What is 650b?

If you're wondering what 650 is, well put simply it's a French wheel sizing system, with a letter designation indicating the tyre width. 650b, with a 584mm outside rim diameter paired with a 38mm tyre, has the same outside diameter as a 700c wheel with a 19mm tyre. 650b was extremely popular in France half a century ago with traditional touring and utility bikes.

Benefits include additional cushioning from the bigger volume of air, providing a smoother ride, and a larger contact patch which boosts traction, ideal for mixed terrain and slippery roads.