Roulette is one of the casino games that give players rather decent chances of winning, particularly when one is playing against single-zero wheels. Despite this, most people are at a long-term disadvantage to the casino, which holds an edge of 2.70% in European roulette and 1.35% in French roulette.
The more you play, the higher the likelihood of you ending up in the red. Some players attempt to beat the game with progressive betting but ultimately fail because this approach is ineffective when it comes to overcoming the house edge.
Yet, there are widely reported stories of players who have won millions at roulette. They have gained an advantage over the house through exploiting biased wheels or using other prediction methods such as visual tracking and dealers’ signatures.
In this article, we are going to discuss wheel bias, what causes it, and what measures casinos take to prevent it. We also cover three other methods of predicting the outcomes in roulette that can give players a significant advantage over the casino.
What Causes Bias in Roulette Wheels?
For a roulette wheel to produce random results, it needs to be perfectly balanced, with evenly surfaced pockets and frets that are equally resilient to prolonged use. The dealer also plays an important role where ensuring randomness is concerned. Tossing the ball in a certain manner, even when done unconsciously, may affect the outcome of the spin.
A roulette wheel cannot remain absolutely random for long periods of time. Frequent use and inadequate maintenance lead to various defects that cause imbalances in the wheels. The longer a given wheel remains in use, the further it deviates from true randomness.
The smallest furrow invisible to the naked eye can impact the trajectory of the ball, causing it to drop in certain pockets more often than it does in others. Such tiny imperfections on the wheel tend to get more pronounced over time causing even bigger disturbances in randomness. Here are the main physical defects that lead to wheel bias.
Wriggly frets 
Defective ball tracks 
Unevenly sized pockets 
Quality and form of the balls 
Wobbling wheels 
Irregular deceleration 
Material the pockets are padded with 
Worn out pockets Wriggly frets
Wriggly frets are one of the most common causes of wheel bias. Frets are used to separate one numbered pocket from another but tend to wear out and loosen over time. The higher these separators are, the more prone they become to potential damage. Some dealers involuntarily push or pull the frets when rotating the wheel which causes some of them to loosen.
When frets are loose, they tend to absorb the impact of the ball better than normal pocket separators. Randomness is disturbed as the ball settles in some pockets or wheel sections more frequently than it does in others.
Defective ball tracks
Defective ball tracks can also lead to wheel bias. This component of the wheel also wears out with extended use, but this normally requires many years. A reputable casino inspects and replaces its roulette wheels with far greater regularity. Worn out ball tracks cause ball rattle which might result in specific drop points becoming more frequent. As a result, a section bias might develop.
Unevenly sized pockets
Unevenly sized pockets might disturb the randomness of results because the ball is more likely to settle in a larger pocket than it is in a smaller one.
Quality and form of the balls
The quality and form of the balls also have an impact on the results a roulette wheel produces. A ball manufactured from a low-quality material is more likely to become deformed. In turn, such deformations make it more susceptible to wheel defects such as grooves and tiny cracks.
Wobbling wheels
Wobbling wheels are common culprits when it comes to disturbing roulette’s randomness. This wobbling is usually caused by tilts where one side of the rotor sits slightly lower than the other one. Gravity pulls the ball down so that it favors the tilted side of the wheel.
Because of this, casinos need to ensure their wheels are uniformly weighted. Apart from this, tilts occur when players are consciously or unconsciously leaning onto the wheel’s bowl rim. Many landbased casinos have installed plexiglass shields to prevent this from happening.
The bias that results from wobbling wheels is relatively easier to spot with the naked eye. Detecting it is also less time-consuming because it does not necessarily require you to record spin results and compile a large sample size. The more pronounced the tilt is, the less random the results become.
Irregular deceleration
Irregular deceleration is another leading cause of wheel bias. A random wheel is supposed to rotate smoothly and decelerate at an even rate. Distortions in the wheel shaft may lead to quicker deceleration when the zero is at a certain point around the base of the wheel. This typically happens when specific rotors and wheel bases are utilized. Irregular deceleration causes sector biases, particularly in situations where there is a pronounced wheel tilt that leads to common drop points of the ball.
Material the pockets are padded with
The material the pockets are padded with also impacts the game’s results. Newer wheels have their pockets’ bottom padded with sturdy plastic material, which leads to greater ball bounce. In older wheels, the pockets were padded with soft material glued with cement.
When pads wear out, they need to be replaced but this process involves a great level of precision and diligence. Sometimes the material the new pads are made of is not completely identical to the one that was originally used. This causes pockets of trapped air to appear during the replacement process, which, in turn, impacts the pads’ resilience.
Pocket pads that are not equally resilient disturb the random characteristics of the wheel. Softer materials are less resilient absorbing more energy from the ball. The ball is retained by such pockets more frequently. Sturdier materials are far more resilient causing the ball to bounce out of the pockets.
Worn out pockets
Worn out pockets with minute scratches on their surface can create sector bias. Even the tiniest of scratches can cause irregularities in friction or impact absorption.
- American and European Wheel Sequences
- High Stakes Roulette
- European Roulette
- French Roulette
- American Roulette
- Roulette Strategies
- Roulette Rules
- Outside Bets
- Inside Bets
- Martingale Roulette System
- Parlay Roulette System
- Fibonacci Roulette System
- Low Limit Roulette
- Roulette – From a Perpetual Motion Machine to a Casino Landmark
- Roulette Basics and Rules of Table Conduct
- Roulette's Bet Types
- The French Roulette Layout
- Independent Trials, Odds, and Casino Edge in Roulette
- En Prison and La Partage
- Taking Your Roulette Game to the Next Level with Call Bets
- The Many Faces of Roulette – Interesting Variations to Try
- Progressive Roulette Systems
- The Master of the Wheel Gonzalo Garcia Pelayo
- Improving Your Roulette Game
- Dispelling Roulette Myths
- How to Protect a Roulette Bankroll
- Software Providers of Online Roulette
- Roulette Games with Progressive Jackpots
- Live Dealer Roulette
- Roulette Goes Mobile
- Roulette in Literature, Film, and Television
Casino Measures against Players Who Exploit Wheel Biases
The trouble with bias is that roulette players are not the only ones looking for it. The casino personnel is also trained to detect anomalies in randomness and deal with them accordingly to hinder advantage play and stop bias exploitation. This is achieved through several widespread practices.
Use of Sturdier Wheels 
Outcome Tracking 
Wheel Maintenance and Inspections Use of Sturdier Wheels
An increasing number of casino operators use sturdier wheels as they are less susceptible to quick physical damage. These wheels first appeared in the early 1980s when UK casinos noticed a significant decrease in the profits they generated from their roulette tables.
The casino operators suspected some players were cheating so they invited police investigators to inspect the tables and weigh in on the matter. The investigators found no traces of foul play and determined players were simply exploiting biases in the wheels.
Since the practice of tracking the wheel for biases is not illegal, the casinos turned to TSC John Huxley, the leading manufacturer of roulette wheels, with the plea to devise sturdier wheels that are less likely to incur physical damages with prolonged use.
This is how the manufacturers came up with the Starburst roulette wheel which is now utilized by many casinos the world over. This type of wheel has lower frets that are manufactured from metal instead of wood. Metal frets are less likely to loosen or wear down over time. Biases result from physical defects which explains why sturdier wheels like John Huxley’s Starburst are so sought-after by casino operators.
Outcome Tracking
Roulette players are not the only ones looking to detect wheel biases. The members of the casino’s personnel also observe for anomalies but unlike advantage players, they are spared the hassles of having to sit around and record spin results manually.
If you have ever played roulette at a landbased casino, you surely have noticed the big electronic scoreboards installed on each table. These boards have a two-fold purpose. For one, they show the last 10 to 20 outcomes the wheel has produced.
This information is used by trend bettors who rely on previous outcomes to place their next bets. Here is an example of how this works. A trend bettor who lays their money down on even-odds propositions checks the board and notices red has shown four times in a row.
The player then reasons black is due to win on the fifth spin and backs this outcome with a higher bet. Based on the Gambler’s Fallacy, this approach is inefficient because previous results do not impact the odds of future spins. Trend betting does not reduce the house edge, either, which is why such players ultimately end up in the red over the long run.
Since trend bettors do not impact the house’s bottom line negatively, casinos try to keep them invested in the game for as long as possible by providing them with readily available information about previous results.
More importantly, the scoreboards have built-in computer chips which collect information about the outcomes the wheels produce. The casino then analyses this data and if there are any anomalies in the distribution of results, the wheel is subjected to further inspections to determine whether or not it should be replaced.
Wheel Maintenance and Inspections
Roulette wheels are properly maintained and regularly inspected by casinos for any physical anomalies that can disrupt the randomness of results. An investigation that took place in the UK established that even the smallest of tilts can create a pronounced wheel bias. In such cases, the casino’s maintenance staff would re-level both the table and the wheel, effectively fixing any imbalances and destroying the bias.
But tilts are not the only thing staff members are trained to cope with. They inspect all physical parts of the wheel that could potentially lead to a bias, including the frets, the pockets’ surface, the wheel’s shaft, its base, and rotor. A defect in a single one of these components can cause an imbalance that leads to biased results. Such wheels are removed from the floor before advantage roulette players notice the bias and try to exploit it.
Other Methods of Predicting Roulette Outcomes
Exploiting biases is not the only method advantage players resort to when trying to beat the roulette wheel. Illustrious gamblers have come up with a variety of ways to overcome the house edge and win at the seemingly unbeatable roulette tables. Some have succeeded through the use of portable computers while others have mastered the crafts of visual tracking and identifying dealers’ signatures.
Computer Prediction 
Identifying the Dealer's Signature 
Visual Tracking Computer Prediction
Ironically, the first portable computer was created in the early 1960s specifically for the purpose of beating roulette. It is the brainchild of Edward O. Thorp, otherwise known as the “Father of Card Counting”, and Claude Shannon, who laid the foundations of the Information Theory.
The device they came up with was small enough for a person to hide it under their jacket. The roulette computer calculated which sector the ball was most likely to settle in by timing the wheel and the ball.
What’s interesting is that this system performed more efficiently on wheels without bias. The trouble was that casinos could easily hinder the person who used the computer by closing the table for wagering before the ball is released onto the wheel.
Later on in the 1970s, a group of students from the University of California Santa Cruz (UCSC) decided to take a break from their academic pursuits and devise a small concealable computer that would allow them to overcome the house edge in roulette. The device was small enough to be concealed in a shoe.
The player would input data into the computer by tapping a tiny switch with their big toe. Using the input data, the computer would predict in which of the 8 wheel octants the ball would land in. This machine would also tell the player when not to make a wager.
Two people were needed for this device to work efficiently. One person would simply observe the game and input data by tapping the switch of the device in their shoe. The other person received the signals through an output system attached to their chest and hidden under their shirt.
This piece of technology proved efficient at the roulette tables, earning the group of students around $10,000. Despite this success, the Eudaemons, as they called themselves, split up after an accident where one of the bettors was badly burned by the device because of insulation failure.
Today, there are modern versions of these devices, some of which are small enough to be hidden into a pen or even pasted onto one’s tooth. The player clicks the device when the ball passes through specific sections or numbers of the wheel track to measure the wheel’s speed and deceleration.
The data is transmitted into a small computer so that it can run its calculations and determine the next winning number. This information reaches the player either through an earpiece or through vibrations.
Keep in mind that the use of electronic devices for result prediction is strictly prohibited in many jurisdictions. If caught, players risk a lawsuit or are permanently banned from the casino’s premises. It all depends on which jurisdiction you are caught using the device in.
The UK Gambling Commission, for example, has granted casino operators the right to deny payment to such players. The use of electronic devices as a means of outcome prediction is considered cheating and is thus unlawful in Nevada.
Identifying the Dealer's Signature
Another form of advantage play in roulette has to do with a phenomenon called “the dealer’s signature”. With this approach, the player identifies patterns in the dealer’s ball-release technique.
Let’s first clarify that it is impossible for any dealer out there to release the ball in such a way so that it repeatedly settles on the same individual number. When looking to exploit dealer patterns, the player determines whether or not the ball is repeatedly released in a manner that allows it to land on numbers within a specific wheel section.
This process is also known as “sector slicing”. It enables the player to gain an advantage over the house by betting on the numbers in the respective section. This is easier said than done with accuracy. Most dealers fall into a routine unconsciously because of muscle memory.
At a start of a new round, the dealer would pick the ball from the pocket it last settled in, take it back to the top of the wheel, and release it again. A dealer with a signature would spin the ball in such a way so that it often lands several pockets away from the number that last showed.
Even when done subconsciously, this leads to controlled instead of random results. Players who resort to this technique do not pay attention to the exact numbers that hit. Instead, they try to establish the distance (in terms of pockets) between the current winning number and the number that occurred on the last spin.
This approach lacks no logic, but there is no guarantee it will be effective when put to practice. For example, if the ball hits one of the deflectors on the wheel, it will bounce off and the outcome will again be random even if the dealer has a signature.
Visual Tracking
Unlike computer-based methods, visual tracking is a completely legal approach toward roulette outcome prediction. This method requires a decent amount of patience, practice, and visual acuity to work. It involves meticulous observation of the trajectory of the ball in relation to the counter rotation of the wheelhead to predict in which section the ball is most likely to land.
This approach yields decent results when the right playing conditions are present. For one, it is said to work on old-model wheels. The ball should be spun fast by the dealer who needs to maintain a stable rotation of the wheelhead at medium speed. A recurring ball drop is also required as well as a heavier, less bouncy ball, inclined to stay several pockets away from where it originally fell onto the wheel head.
The method requires a very good view of the wheelhead and the ball, which is why it works best when two people utilize it as a team. One person tracks the ball’s trajectory and gives signals to their collaborator who places the actual wagers.
The best position for a visual tracker is right next to the wheel where the plexiglass shield is, immediately next to the last table seat. This way the bettor can get a clear view of the tracker’s signals and act accordingly.
The bettor, on the other hand, should sit toward the back of the table, immediately next to the dealer. This allows them to effortlessly see the tracker’s signals and gives them easy access to the betting layout.
The trouble is many casinos no longer use old-model roulette wheels, opting for a newer, sturdier design with shallower pocket separators. Visual tracking is less likely to work in such playing conditions.