Most tubeless tires have a thick side-wall that locks into a specific sealed-bed rim. These tires can take a beating over rough terrain so they are ideal for downhill, but the downside is that they are more expensive.

The benefits of an airtight seal and a durable, low pressure performance are outweighed by the cost. They also require a clean rim and tire to fit them, and a big pump to inflate them.

Clean conditions are usually unavailable if the tire has to be replaced on the trail. And even with a C02 cartridge pump you’ll usually have to use an inner tube to get you home and then repair the tire later. Also while small holes might be repairable, a big hole can mean the tire is completely written off as well.

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The wider rim also widens the tire contact patch, reduces incidence of pinch flats, and allows lower air pressure for a smoother ride with lower rolling resistance on clinchers, and it increases the gluing area and tire retention of tubulars. The idea of a wider road rim is that the airflow over the tire is improved to drop the overall drag of the wheel, and bigger tires with lower rolling resistance and greater cornering grip will fit on them. Rolf Prima’s new TDF 60SL wheel has a 23mm-side, 60mm-deep full-carbon tubular rim with an 11mm rim bed radius to precisely fit a 22mm tire. Rolf Prima’s paired spokes can be run at high tension because the spokes oppose each other, whereas tight spokes with low spoke count would otherwise tend to pull the rim back and forth. “The UCI won’t allow less than 12 spokes in mass-start races, but with our paired spoking, we can make this a strong wheel with 10 spokes as well,” says senior design engineer Joel Wilson. It is available with either 16 spokes front and rear or 12 spokes front and rear.

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