Cycles of all sorts

Metal

Metal drain covers are often placed in the part of the road where cyclists ride, particularly at junctions. These become slippery in wet weather especially after a dry period when rubber particles and a film of oil have built up.

A variant on this is the drainage grate with slots that run parallel to the direction of travel. These can easily grab a cycle wheel and cause a crash. There are several alternative bicycle-safe designs that use holes that will not grab a bicycle wheel; best practice indicates that cyclists should in any case ride further out than the drainage grates.

Railway tracks crossing the road are particularly hazardous, combining polished metal surfaces and deep channels which can trap a wheel and throw the rider off the bike. The worst case is when the tracks cross the roadway at an angle, which makes it even easier for the front wheel to be thrown off course. The standard advice is to cross tracks at a right angle, or as near to a right angle as possible.

Speed bumps

Speed bumps used as traffic calming devices on public roads are designed according to an accepted standard and present little hazard to bicyclists. Some of the desirable design features are a smooth transition from the road surface and a limited slope. In contrast, speed bumps on private or non-public roads and parking lots don't have to meet standards, and are therefore usually of a more varied design and could present hazards to cyclists. One example is a bolt-on rubber speed bump with an abrupt edge that can cause a bicycle front wheel to turn sharply and eject the cyclist.