Wheelchair

The wheelchair, or upside down barrel roll, is a technique dependent on barrel roll collision used to avoid out-of-bounds (OOB) collision.

Overview

There were numerous videos in the past of people mysteriously bypassing OOB, such as this one from Justin dating back to around 2014. In common between them was the vehicle being upside down, or close to, at the time of bypass. The exact part of a vehicle that triggers OOB is currently unknown (assumed to be a location on bottom of the vehicle body), but years ago was thought to be the wheels.

A barrel roll (see barrel roll for additional information) is a technique which can be performed after coming into contact with specific surfaces in a track. In a barrel roll state, your bike tilt unlocks, letting your vehicle achieve rotations that otherwise wouldn't be possible to sustain, granting you the ability to input a wheelie multiple times until you perform a backwards somersault and tip upside down. For this to work, your internal velocity must be under 15u/f. If you obtain more than 20 frames of airtime in this state, the bike will automatically flip back to its regular rotation.

In January 2020, cf uploaded a video titled "wheelchair needed", which demonstrated a potential ultra shortcut idea on DS Desert Hills. He planned to drive over the solid OOB by using the barrel roll collision on the lake's edge to tip upside down and avoid OOB detection due to the wheels being far enough away from the ground. The sloped surface of the sand caused the vehicle to tip over shortly after, hence cf's statement of a wheelchair being needed for support. The idea was deemed dead due to the sheer instability of the bike and its frustrating tendency to tip over no matter what.

Later, in April, cf found a flap-only ultra shortcut on the N64 Kalimari Desert custom track using the wheelchair. To solve the instability issue, he used the Tiny Titan kart, in the hopes that its four evenly spaced wheels would be beneficial. Since wheelies aren't possible on karts, he cleverly used the edge of a ramp to tilt the kart from a height and guide its fall as it tilted back. Despite the setup needing a lot of time, this strat sparked hope for a functioning bike variation in the future.

Meanwhile, a promising ultra shortcut idea for DS Peach Gardens was being developed. It required over 20 seconds of an untipped wheelchair, so more testing of the tech itself with a bike was required to see if what was needed was actually possible.

Eventually, an infinite wheelchair was proven to be possible on bikes by Ejay in January the next year. In an attempt to test the tech without the hindering effects of sideways bike movement and tilt, he used a multiplayer VS Race on SNES Ghost Valley 2. By using a second player to drive into the blocks behind the finish line and remove them, Ejay was able to reverse from the race's starting position (without using the joystick) perfectly perpendicularly onto an edge with barrel roll collision. He was able to stay upside down forever, noting that joystick directions after falling upside down had no effect on bike tilt.

The hole in the DS Peach Gardens theory wasn't properly filled until a handful of days later, when Charlie managed to perform an infinite wheelchair notwithstanding having driven around beforehand. In a video titled "wheelchair no longer needed?", and even using the same barrel roll location hypothesised in the ultra shortcut theory, Charlie discovered that repeatedly wheelieing while stationary slowly reduced his Z-axis rotation to 0.00, at which point he chose to tip upside down, and, to his surprise, remained there forever with a Z-axis rotation of 0.02.

After carrying a barrel roll to the OOB seam next to the DS Peach Gardens finish line, cf finally replicated what Charlie did, and got an ultra longcut on March 2. By implementing incredible QM-based checkpoint movements , he turned it into a time-saving ultra shortcut on March 6. Thanks to this, the infinite wheelchair on bikes finally got the fame it deserved.

Strategies

• DS Peach Gardens ultra shortcut
• DS Desert Hills kart ultra shortcut
• Koopa Cape kart ultra shortcut
• DS Desert Hills Wario Bike superslide setup
• N64 Kalimari Desert ultra shortcut
• GCN Daisy Cruiser ultra shortcut
• Cherry Blossom Garden ultra shortcut