Many of our styles feature Vibram branded rubber soles, which is an extremely durable material. The ridges provide added traction - particularly when ascending steep climbs on the trail. The compromise for ensuring the rubber is hardy is that they can be a bit slippery on urban surfaces.
It's important to keep in mind that as a hiking shoe, they are designed to last on rough, off-road terrain. Over time and with use, the sole with roughen up and grip better on urban surfaces.