Mavic have expanded their range of big wheels by adding three new 29er hoops to their collection for 2013.

The French company tentatively dipped their toe into the water in 2011 with the launch of the C29 wheelset but that has, until now, been the firm’s only 29er offering. That’s changed with the launch of the race-ready Crossmax SLR 29, trail-focussed Crossmax ST 29 and budget Crossride 29 hoops.

The wheels were launched in June and we’ve already tested the “light, stiff and bombproof” ST 29 wheelset – read the review here – but Eurobike gave us the chance to take a closer look at the top-of-the-range SLR 29.

While the ST’s are essentially a supersized version of the 26-inch equivalent, the SLR’s have taken some fastidious engineering to ensure the weight is kept down without sacrificing strength and stiffness. In fact, Mavic wanted to unveil the SLR wheelset in 2011 but it’s taken an extra year of development for them to be happy with the finished product.

Mavic told us a 29-inch wheel is 39 per cent less stiff than a 26-inch wheel and heavier by somewhere in the region of ten per cent, while a big wheel has 40 per cent more inertia, which can affect reliability. So Mavic set about overcoming both hurdles with the help of riders from the Cannondale Factory Racing team.

First they increased the number of spokes from 20 to 24. That improved stiffness but came with an unacceptable weight penalty as Mavic have designed these as cross-country racing wheels, so they switched back to 20 and tried stronger spokes.

That partly solved the problem but Mavic then started noticing cracks in the rim. The solution? Increasing the thickness of the rim’s sidewall by 0.6mm. Problem solved? Not quite. The stronger rim only moved the stress to elsewhere in the rim and spokes were snapping on the driveside of the rear wheel. Mavic overcame this by bead blasting those spokes to increase strength without incurring a weight penalty.

The result is a wheelset which weighs 1,620g and costs £850, and which was ridden to bronze by Marco Fontana in the London 2012 Olympic mountain bike race.

Continental unveil semi-slick Speed King tyre

Meanwhile, we also spotted Continental’s Speed King tyre at Eurobike. The new tyre is designed for racing on hardpacked or paved surfaces with a semi-slick tread which Conti told us offers 18 per cent less rolling resistance than the lightweight Race King. Claimed weight is 430g and it’s available, for now at least, in one 26×2.2in size.

Otherwise, we’re heading into the cyclo-cross season and the Continental CycloXKing tubular, which has been doing the rounds as a prototype for a while now, will be available to the rest of us from the end of September. It uses Conti’s excellent Black Chili compound, with a tread pattern based on the X-King mountain bike tyre (with tall shoulder lugs for grip on loose and wet corners).