Cyclocross and gravel rims

wider than a road one to support a tyre around forty millimetres, but not as massive as a mountain bike rim. The width is crucial, because on gravel you ride at a lower pressure and the tyre needs lateral support. A deeper profile helps aerodynamics on the flat, but pushes the bike in a crosswind. A tubeless setup is more the rule than the exception here, so look for a compatible profile and tape. When buying a pre-built wheel, also check how many spokes the rim takes.