A dropout , path or pat section at the end of the front or rear fork of a bicycle frame to which the axle is secured . The wheel axle is not completely enclosed by this construction, so that the completely assembled wheel can be easily removed and mounted.
In many cases, a distinction is made between dropouts, depending on the shape of a dropout. In case of vertical dropouts the wheel is arranged vertically in the frame and the wheel is in the same position. Horizontal dropouts can be applied to rear wheels; As a result, the wheel can move for some distance and shifted backward or forward (by means of the chain tensioner) during assembly, so that the chain can be placed under tension. Horizontal dropouts can be directed forward or backward. They are directed to the front, so the wheel can be easily removed without detaching the chain. This construction are encountered in road bikes. They are directed towards the rear, as in the classic Dutch bike, but also with a track bike, the disassembly is difficult.
Dropouts may be provided with lugs with eyes to put fenders, racks, rear derailleur, seatstays and so on to. Fork-dropouts for bikes with disc brakes have the risk that the wheel, when not properly secured, quick release and with hard braking runs from the fork. These dropouts therefore have often a ridge, “lawyer’s lips” called, with which this is prevented. It is then that the quick release for removing of the wheel needs a few extra turns to get it loosened.