Rear suspension

Historically, rear suspensions have been one of three designs: hardtail, plunger and swingarm. Hardtails still exist in name through the Harley line, but this is a marketing and fashion statement rather than a technological need. Real hardtails have no shock absorbing features other than the cushioning provided by the tire, seat springs and rider's spinal column. Modern hardtails have a shock mechanism keenly hidden from view to provide the "hardtail" look.

The plunger suspension separated the rear wheel from the rigid frame via a small spring device permitting limited vertical rear wheel travel.

After World War II, the swingarm design became the standard rear suspension. The swingarm design is a pivoting fork (or cantilever) generally attached to the lower section of the frame. Shock absorbers can be placed on both sides of the swingarm, which is the conventional layout. But there is no inherent reason for this design. On trail bikes a single shock (a.k.a. monoshock) is attached to the frame and swingarm near the fulcrum, allowing for greater suspension travel.