In a roller the disc lands on edge and rolls most of the distance. When it makes sense, types, disc choice, terrain, mistakes, rules and safety.
The honest answer: a roller is a throw in which the disc lands on edge and rolls most of the distance along the ground. An Innova manufacturer blog sums it up: rollers use the same form as air shots, just with a different release angle and direction; the author advises focusing on accuracy and timing instead of power [1]. It has four variants: with anhyzer, as a flip roller, with forehand or with backhand [1].
Because I read only a retailer/manufacturer source, everything below counts as practical experience. Test it on a safe field.
How hard is it? You need backhand basics, a feel for angle and ground, and patience. There is no timeline.
The blog distinguishes four types: anhyzer rollers (stable disc on a severe anhyzer, maximum distance), flip rollers (less stable disc flat or on hyzer that turns into a roller mid-flight), forehand rollers (usually overstable discs that land nearly vertical) and backhand rollers (a right-finishing option for players who avoid forehands) [1].
Milestone: You can explain which roller you choose when.
Use your normal throwing form and change only release angle and direction [1]. The blog warns against abandoning your mechanics [1].
For the anhyzer roller you hinge at the hips, pull the disc high across the body and follow through downward so the disc reaches the ground quickly, before it starts to hyzer [1].
Milestone: The disc lands on edge without tilting beforehand.
The angle at which the disc meets the ground shapes the roller; more cut angle sends it further left (right-hand backhand) [1]. Play with the angle in groups of ten and note it down.
Before you plan a roller on the course, throw it ten times on a free field at half speed. Note disc, angle and roll distance (practice). On the course a roller is the wrong moment to experiment.
Uphill rolls shorter and the disc acts more overstable, downhill it gains speed and turns more; in uneven woods use forehand rollers for scrambles rather than distance [1].
Milestone: You estimate the roll on field, path and slope before the throw and are within 20% in three of five cases (practice measure).
Change one thing per roller: either angle or disc or ground. The blog names the factors: disc stability, landing angle, disc speed and terrain [1]. Anyone who changes only one variable recognises what it does. Also keep a small notebook or phone note: disc, angle, ground, result. After two practice rounds you have your own table that no video replaces. And check the rolling stretch to its end before every throw.
A throw in which the disc lands on edge and rolls most of the distance along the ground [1].
It depends on the type: stable disc on a severe anhyzer for anhyzer rollers, less stable disc for flip rollers, usually overstable disc for forehand rollers [1].
On low-cut grass or dirt without rocks and roots; tall or wet grass slows it quickly [1]. Downhill the disc gains speed, uphill it gets shorter [1].
Where the disc first comes to rest [2]. If it rolls over the out-of-bounds line and stays there, it costs a penalty throw [3].
Flex Shot in Disc Golf: S-Curve with an Overstable Disc on Anhyzer