Supergrinding

Not to be confused with supergliding or supersliding.

Supergrinding

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Class	Glitch
Type	External velocity exploit
Date found	Late 2012
Theoriser(s)	Black
Discoverer(s)	Black
Timesave	N/A

Supergrinding is an external velocity (EV) exploit used to increase speed by performing RFH while alternating the joystick between some horizontal direction and neutral every other frame. This joystick alternation, commonly referred to as "SG inputs", only has an effect on bikes.

Technical description

It is not yet fully understood why alternating the joystick builds EV. Below is a rough explanation.

After having started performing RFH, you alternate the joystick inputs such that you are inputting a horizontal direction on the frame you press B (creating an angle hop), and neutral on the frame you release B (to prevent committing). This allows you to build EV, and if done long enough, move at a maximum of 120 XZ for an extended period of time.

90 degree rule

Whenever you perform RFH, you approach a change in slope and repeatedly hop to lock your rotation to the initial slope. If you supergrind long enough, the small amount of rotation from the angle hops will start to stack up, immediately taking you off of a straight path. If you turn more than 90 degrees away from the downhill direction of the initial slope, you will be prematurely ejected. This is due to the fact that your roll is constantly moving to the side, and eventually your front wheel will pop out of the ground. As a result of this rule, a lot of tracks with RFH spots do not have supergrinds, because the slopes are facing the wrong direction (e.g. GBA Bowser Castle 3 and SNES Ghost Valley 2).

Relevant code

For Vabold and other programmers.

Variations

ODB supergrinding

Video: "[MKW TAS] Shooting Star Supergrind Strat on Grumble Volcano" by Ancient

Using an ODB, you can perform a different, much more versatile range of supergrind setups. Plenty of IDB setups are impossible or slower with ODBs, however the ability to start a supergrind instantly while moving the direction you want to move and facing the direction you want to face, proves to incredibly useful.

Downhill supergrinding (DSG)

Video: "Downhill Supergrinding using a Kart (DSG)" by Kierio05

When RFHing downhill, you can build external velocity without inputting any joystick directions. This has the major benefit of allowing karts to supergrind.

Optimizations

Ejection

When reaching the end of a supergrind, you will have surplus amounts of EV. In order to maximize the use of it, you can "eject" from the supergrind by stopping hopping and performing some other action(s), such as drifting, wheelieing, or momentum hopping.

Angle drop

Often, at some point in a supergrind, you will approach another change in slope which causes your vehicle to become further tilted into the ground, losing speed. When this occurs, the best option is to stop and restart the supergrind by delaying a single hop for 1-2 frames. This will drop your angle to be level with the new ground.

Hard turning

Not alternating the joystick results in turning significantly more, at the cost of gradually losing EV. This happens because you are holding a direction on the second frame of each hop, and so are committing to a direction, which rotates you for that 1 frame. This can be useful if you are in a situation where turning faster matters more than building or maintaining EV.

Softgrinding

Traditionally, supergrinds are best used on long straights. The problem with this is that you will eventually stop going straight, and veer off the track. The most common way to stop yourself turning is just holding neutral on one or more hops, as this will prevent your EV from increasing. However, holding neutral will begin a slow redirection of your movement back towards your facing direction and you will gradually lose EV. A way to prevent this is just to hold a lower magnitude direction throughout the supergrind, using the smallest magnitude that has any effect on your roll: ±2.

Counter-rotation

Video: "Optimal Supergrind Counter-Rotation" by Kierio05

Even with softgrinding, you will eventually turn too far, and so correction is required. The naive way of counter-rotating is to alternate the joystick in the opposite direction, or even hard turn the opposite direction. However, by alternating the joystick back and forth between one direction and another, you can gain EV from the angle hop, and then commit to hopping the opposite direction, countering the rotation. As you rotate significantly less during the angle hop frame, counter-rotation can actually be used to traverse turns in the opposite direction, however the more you counter-rotate, the more EV is lost from doing so.

Applications

Applicable categories

Type	Unrestricted	No Ultra	No Glitch
3lap	Yes	Yes	Banned
Flap	Yes	Yes	Banned

Supergrinding is currently used in many 3lap and flap categories, and is used both on its own and to perform the following strats:

• LC ultra shortcut
• MC shroomless ultra shortcut with ODB
• DDR ultra shortcut
• MH ultra shortcut
• BC ultra shortcut
• rPB shroomless delayed lap count
• rYF ultra shortcut (including delayed lap count)
• rMR hill shortcut
• rDS fountain shortcut

Supergrinding has also been used in TASes on the following custom tracks:

• Big Express City
• Hman's Deathrun 2
• Lunar Spaceway
• Sagittarius Circuit