What is running side in snooker?

Running side is side spin that matches the direction the cue ball will travel along a cushion after impact. The cue ball comes off the cushion at a steeper angle (further away from the cushion). Used when you need the cue ball to travel further across the table after a cushion contact.

What is check side in snooker?

Check side is side spin opposite to the cue ball's cushion travel direction. The cue ball comes off the cushion at a flatter angle, slowing or stopping near the cushion. Used when you need the cue ball to stop in a precise spot rather than overshoot.

Should I use side spin on long pots?

No. Side spin causes squirt (cue ball deviates opposite the side) and swerve (curved path from cloth friction). Both errors compound at distance, so a long pot with side typically misses by 15-30% more than the same pot with centre cue ball. Always use centre cue ball on long pots.

What is squirt in snooker?

Squirt is the cue ball's deviation from the cue's pointed direction when you strike off-centre. Hit right-side and the cue ball squirts left of where you aimed. Typical offset is 2-5 mm at 4 ft distance, depending on cue stiffness, tip hardness, and ball condition. To compensate, aim slightly opposite the squirt direction.

When should I avoid using side spin?

Avoid side on long pots, when the cue ball won't contact a cushion after impact (side does nothing useful), when potting with the rest (cue motion is too restricted), and when unsure (default to centre). Side is a deliberate cushion-management tool, not a habit.

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Snooker Technique · 8 min read

Snooker Side Spin: Running vs Check Side Explained

Updated 16 May 2026 · The technique most often used wrongly at club level

Side spin — striking the cue ball to the left or right of centre, putting "side" on it — is the most fashionable shot at amateur level. Beginners love using it because it looks like advanced play. Pros use it sparingly, because it costs accuracy and only helps in specific situations.

This guide is the one most club players need: a clear explanation of what side actually does, when running side is correct, when check side is correct, and how to manage the two side effects (squirt and swerve) that wreck aim if you don't account for them.

The 3 Effects of Side Spin

When you strike off-centre horizontally, three things happen to the cue ball — only one of which is the "good" thing players are usually after:

1. Cushion Reaction (The Useful Effect)

When the cue ball with side hits a cushion, it leaves the cushion at a different angle than it would without side. Side that matches the direction of travel ("running side") makes the cue ball come off the cushion at a sharper angle. Side that opposes ("check side") makes the cue ball come off straighter, almost stopping along the cushion.

This is the reason side spin exists in snooker. Side is fundamentally a cushion-management tool, not a potting tool.

2. Squirt (The Annoying Effect)

When you strike off-centre, the cue ball doesn't actually go where your cue pointed. It "squirts" off in the opposite direction of the side. Hit right-side → cue ball moves slightly left of intended line. The amount varies with cue (stiff vs flexible shaft), tip (hard vs soft), and ball cleanliness — typically a few millimetres at short range, more at long range.

To compensate: aim slightly opposite of the squirt direction. Or more simply, avoid side on long pots entirely.

3. Swerve (The Other Annoying Effect)

Side spin imparts a tilt to the cue ball's rotation axis. As the ball rolls, friction with the cloth gradually curves its path — this is "swerve". Slow shots swerve more (more time for friction to bend the line); fast shots swerve less. Cue elevation (when forced to cue over an obstruction) dramatically amplifies swerve — a deliberately massé shot is just an extreme side+elevation combination.

The combination of squirt + swerve makes side wreck your aim line in unpredictable ways. That's why pros use side rarely and only when they need the cushion reaction.

Running Side vs Check Side

The terms are simple once you see the geometry:

Running side: side spin that matches the direction the cue ball will travel along the cushion after impact. Cue ball comes off the cushion at a steeper angle (further from the cushion).
Check side: side spin opposite to the cue ball's cushion travel. Cue ball comes off the cushion at a flatter angle (closer to the cushion, sometimes "checking" almost still).

Example: cue ball moving toward a cushion at 45° from your left, will then travel right after rebounding. Right-hand side = running side (matches the right travel direction). Left-hand side = check side.

When to Use Running Side

Bringing the cue ball back across the table after potting a ball — running side makes the cushion send it further across.
Hitting cushions to escape snookers — running side helps reach the target ball after the bounce.
Coming off two or three cushions for positional play — running side preserves angle through multiple cushion contacts.

Rule of thumb: if you want the cue ball to travel further after a cushion contact, use running side.

When to Use Check Side

Stopping the cue ball near a cushion after impact — check side prevents the cue ball from running far down the cushion.
Coming back to a tight spot near baulk — check side off a cushion can land the cue ball on a precise spot rather than overshooting.
Safety play — check side after impact can leave the cue ball almost dead on the cushion, hard for the opponent to play off.

Rule of thumb: if you want the cue ball to slow or stop near the cushion, use check side.

When NOT to Use Side

Probably 80% of the time. Specifically:

On long pots. Squirt and swerve compound at distance. Even with compensation, accuracy drops 15-30%. Centre cue ball is always the right choice on long pots.
When the cue ball isn't going to contact a cushion after impact. If there's no cushion in the cue ball's future, side does nothing useful — only squirt and swerve.
When potting using the rest. Rest stance + side = unreliable. The cue isn't held firmly enough for accurate sidespin delivery.
When in doubt. Default to centre. Side is a deliberate choice, not a habit.

"If you're using side just because you can, you're using too much side." — paraphrased from countless snooker coaching books.

Managing Squirt and Swerve

You will use side sometimes. When you do, two adjustments help:

Adjust Aim for Squirt

Imagine cueing with right-hand side. The cue ball squirts left (opposite direction). To compensate, aim slightly right of the intended line. How much? Depends on your cue — typical low-deflection cues need 2-5 mm at 4 ft distance.

The only way to know your cue's squirt is to practise. Set up a straight cushion-bounce shot, hit it with right side and aim at the intended cushion point, see where it actually lands. Adjust until consistent.

Reduce Swerve by Hitting Faster

Slow + side spin = significant swerve. Fast + side spin = minimal swerve. If you must use side, prefer a firmer pace where possible. The cue ball's path stays closer to the line you cued.

Don't Combine Side with Screw or Follow

Some pros do this, but for amateurs it's a chaos multiplier. Combinations of vertical and horizontal off-centre strikes compound errors. Stick to one or the other.

Build cue-ball control before you build cue-ball acrobatics

Side spin only earns its keep on top of solid centre-cue-ball fundamentals. AimGeometry's cue-action drills and the 30° rule are the foundation; side is an advanced layer built on those.

Open Lesson 4.1 · Spin Fundamentals →

The Side-Spin Decision Tree

Before applying side, ask 3 questions:

Will the cue ball hit a cushion after impact? If no — no need for side.
Do I need the cue ball to react differently off that cushion than it would naturally? If no — no need for side.
Is this a short-to-medium pot (under 5 ft)? If no — too much squirt/swerve risk. Find another way.

If all three answers are "yes" → choose running or check, dial in the amount based on how much cushion adjustment you need, compensate for squirt. If any is "no" → don't use side.

Drill: Calibrate Your Cue's Side

15-minute drill, do once a month:

Place the cue ball on the brown spot.
Aim straight up the table at a known reference (a chalk mark on the top cushion).
Hit with maximum right-hand side at medium pace, aiming directly at the chalk mark.
Note where the cue ball actually contacts the cushion. The offset to the left of your aim = your cue's squirt at this distance and speed.
Repeat with left-hand side; verify it squirts the same amount to the right.

This gives you a "squirt number" for your cue. Calibrate it; remember it; use it for compensation when applying side.

One-Sentence Summary

Side is a cushion-management tool that costs aim accuracy — use it only when you need a non-natural cushion reaction, never on long pots, and always with awareness of the squirt and swerve it adds.