First of all, I am going to skip right over the philosophical debate of whether flying discs should be rolled or not. I have heard the arguments by flight purists who proclaim that rolling a disc is evil, as they were designed to fly, not roll.... and how the flight of a disc through the air is inherently more appealing than the rolling of a disc.... yadda yadda yadda. Hogwash I say! The stinkin' disc is ROUND! It rolls great! If discs are not intended to roll, they should be made square. If you stand on the tee pad of a hole that is best thrown with a roller drive, and refuse to throw a roller... I can tell you one thing', somebody who knows how to throw a good roller is going to score better than you. Any way you can get your disc near the basket is ok with me. Throw it upside down for all I care, results are what counts (as long as you don't cheat). Oh dang... I was going to skip over this debate. Hmph.
When do you throw a roller? Obviously enough, rollers should be thrown when the hole you are playing requires it. If your odds for achieving a good shot are better on the ground than in the air, you should throw a roller. Take a look at the area you want to throw through. Is it too long to reach in the air? Are there too many trees in the way? Consider a roller.
Knowing how to throw a roller properly and effectively is essential to every disc golfer's game. If you do not know how to throw at least the four different kind of roller shots that I will talk about, you should learn them. They will shave strokes off of your average round.
1: Distance Drive Roller Most players can roll a disc about 10arther than they can throw a disc. So, if you can only throw a driver 300 feet, you should be able to roll the same type of disc 330 feet. Very handy if you are playing a hole that is 340 or 350 feet long... a roller may get you a birdie attempt. If you cannot reach the hole with either a roller or airshot, you should probably consider throwing an airshot as long as the fairway is conducive to that, as it will probably get you a par more often in that case, because a roller may be more likely to go astray in a bad way. Then again, if the hole is REALLY far away (500, 600 feet or more), an extra 40 or 50 feet farther down the fairway provided by a roller drive may make a par that much easier. You will have to decide.
So, how do you throw a distance roller drive? Start by choosing a fairly fast, understable disc. I prefer a Stingray, but there is no end to the number of discs that will work well for a roller. If you don't have a roller disc simply find the most beat up, used up, piece of junk, turn over distance driver (Cyclone, XL, Cheetah, Gazelle, Polaris - something like that) that you have.
The angle of release for a roller is different than a regular throw. The posture of your back as you throw will need to be more straight up and down (you will stand up straighter as you throw). Sometimes, depending on the shot, you will even need to arch your back a little. Instead of coming straight across your chest and releasing the disc straight, you will want to pull the disc across your chest area and release it above your shoulder line, even above your head line. Stand on the tee pad and look straight down the fairway and imagine the face of a clock in front of you. if you are right handed, for a normal drive you want to pull the disc across your body and release it around the 9 o'clock position. (Ok, I know, I know, many of you don't know what the hands of a clock look like, you've only seen digital clocks your whole life.... work with me on this one, in fact, go ask your grandparent what the hands of a clock look like). A roller does not release at the 9 o'clock position, but more like 10 or 10:30, the throw is higher, above your shoulder. Your run-up across the tee pad should be the same as it is for a turn-over drive. (For a right handed player, the norm would be to start at the bottom right of the tee pad and finish at the top left).
After you release it, the disc should fly before touching down to ground. (The amount offlight before coming to ground will depend upon the fairway you are throwing on, and the obstacles you need to avoid. In general, you don't want the disc to come to ground real early, but you don't want it to fly far enough to lose its velocity either. You want the disc to turn over more in the air, then hit the ground with plenty (plenty!) of velocity. The disc should land at an angle with the top of the disc still a couple inches short of standing straight up vertical. The disc should travel in an "S" pattern: traveling from the left to the right while in the air and turning over, then moving to the left after hitting the ground, but the disc starting to stand straight up while doing this, then standing straight up and turning over to the right (the top of the disc now past straight up vertical) with the flight plate of the disc leaning toward the ground. It should finish its roll by turning right and gently falling over on its face.
Depending on your disc, and you will have to experiment to find out what works well, you may have to release it turned over, or discs that are really beat up may require being released flat. If your disc does not stand up and turn over while rolling, then try releasing it with more turn over angle, if it turns over too fast, then try less angle. You get the idea. if your disc is not hitting the ground with good velocity then try throwing it lower through the air before it hits ground. You still need to use good throwing technique and good backward extension to get velocity on the disc. (See License to Drive article on the web site).
#2: Short to Medium Drive Control Roller Once you learn how to throw the distance roller described above, you need to learn to throw the same type of shot for controlled medium range shots. A good strategy is to use a slower disc, a Panther works well or a Stratus (but I use a Stingray for this shot also, too many discs confuses me... see my article on disc selection following). You will need to modify your release point, and angle of release to get the disc to turn over faster and sharper (release higher and more turn over angle, also experiment with arching your back more to get the disc to turn faster), hopefully resulting in coming to rest near a pin that you have had trouble reaching before you learned this shot. This type of drive works really well for short turn over drives with heavy tree coverage near the basket.
#3: Short to Medium Drive Sky Roller This shot is the same type of shot as the medium roller, but is necessary when you have heavy tree coverage (or some other sort of obstacle) in front of the tee pad. The big difference is the flight the disc takes through the air before coming to ground. It is possible, with practice, to throw over the top of obstacles in front of the tee pad, then have the disc land on a good rolling angle and execute a good drive. The angle will probably need to be more toward standing straight up and down than your regular roller, as the disc will lose velocity during its sky-high flight. Therefore, give it a little more angle, so it will roll straight and then turn over.
#4. Two Finger Upshot Roller This is a very handy shot and should be learned by everybody. Hopefully, you will not need it everyday, but it can save strokes when you do need it. Do you find yourself 75 feet away from the pin with heavy tree coverage between you and the basket? Is an air shot from this lie likely to hit trees and fall short of the pin, or is a tree directly in front of you obstructing your throw? Throwing a side-arm roller will get you within putting range if you know the shot. Hold the disc in a side-arm fashion, with your middle finger against the inside rim of the disc. Pinch with your thumb. This shot is really not much more than a flick of the wrist, not much arm motion at all. Its almost a half-throw. Just pull the disc back so it is just past your shoulder, and then smoothly throw forward, careful not to roll your wrist over (like you would if throwing a baseball), flicking your wrist at release. The closer you are to the basket the more you wilt want to start the disc standing up from the beginning. It will travel fairly straight and then turn hard left at the end, even curling and traveling backward toward you a little before stopping (take that into consideration when aiming the shot and judging speed.