Rollbacks are most common (though still quite rare) on the world's largest launched roller coasters like
Top Thrill Dragster at
Cedar Point and
Kingda Ka at
Six Flags Great Adventure, along with somewhat smaller rides such as
Stealth at
Thorpe Park and launched roller coasters of the same type, such as
Xcelerator at
Knott's Berry Farm and
Storm Runner at
Hersheypark. There are several factors that can cause a rollback, all of which are related to the train's speed. Among them are: • Unusual wind gusts could slow the train down enough to cause it to roll back. • Cold weather increases
friction between the wheels and the track, which may slow the train down enough to cause it to roll back. • Until the launch motor has been sufficiently warmed each day (which only occurs after a certain number of launches), it may not be generating quite the full amount of power needed to accelerate the coaster to full launch speed, which may also cause a rollback. Intentional rollbacks are sometimes conducted during testing. While the general public may not realize that rollbacks usually are completely safe and that coasters are designed with them in mind, many coaster enthusiasts look forward to being in one. Being in a rollback essentially gives riders a ride and a half, as the train will be launched again after the rollback. On some rides, when a rollback occurs with people on board, the train will first be brought back to the station to give the guests the option of getting off; other roller coasters with dual-train dispatch systems disallow backwards returns to the station and the train will simply be launched a second time without the option to disembark.
Unusual circumstances On extremely rare occasions, a single train may require more than two launches to clear the highest point of the track. Very rarely, a train is launched with just enough speed to reach the track's highest point, resulting in the train getting stuck on the top. This results in neither a full ride nor a rollback. This happened three times on
Top Thrill Dragster. All three times, a ride mechanic had to take an elevator to the top, and give the train a small push so it could complete the ride. It has also happened twice on
Stealth at
Thorpe Park, both during early morning tests.
Maverick at Cedar Point tests roll backs every morning during testing. ==Examples==