Aprilia, the Italian motorcycle and scooter maker, started out making small-displacement machines and has branched out considerably since then. It introduced the RXV, an off-road-racing bike, in 2006, producing two models, the 4.5 and the 5.5 (also known as the 450 and 550). These models were carried over for the following years. In the interests of broadening its market, Aprilia made an effort to make the bikes street-legal in 2008 and 2009.
The 2009 RXV 4.5 has a 449cc, liquid-cooled V-twin engine set at a 77-degree angle; the 5.5, as the name indicates, has a 549cc four-stroke engine. Both engines are fuel-injected, with a single overhead cam with rocker exhaust valves and four valve heads. The valves themselves are titanium. An integrated electronic management system controls ignition and fuel injection. A rider can switch power modes to match track or trail conditions. Aprilia moved the choke from the handlebars to the filter box and offered two different exhaust silencers in 2008: the standard under-seat tail pipes or stainless-steel side-mounted pipes. That design was retained for 2009. The chain-driven five-speed transmission features Enduro gear ratios.
A lightweight steel perimeter frame with alloy vertical members keeps the bike’s weight down to 262 pounds, which makes it great for jumping downed logs on the trail, but perhaps a bit too light for safe street riding. The front suspension is an adjustable inverted Marzocchi fork; rear suspension is a Sachs twin-sided swing arm with a spring pre-load adjustable shock and rebound damping. Stainless-steel 10.7-inch hydraulic disc brakes with a floating caliper in front and a 9.5-inch disc rear brake, also with a floating caliper, stop the RXV.
Designed with an Enduro course in mind, the bike’s handling is tight and nimble, and the engine provides power to spare. It is street-legal in some states, but the head and tail lights may not meet all states’ requirements. It is certified by the California Air Resources Board. Many riders comment that the suspension feels rather insecure on the street, but perfect on dirt. The stock knobby tires are also well suited to dirt, but not pavement. Its angular styling is eye-catching on or off the road.