The concept of wheel bias has existed for just about as long as the game of roulette itself, which makes it more than 200 years old. As with all forms of gambling, or indeed any activity where there is money to be made, those involved are always looking for an edge, some form of advantage that can help them win. As with many such ideas and concepts, using wheel bias to gain an advantage over the house (casino) is something of a grey area in terms of its legality and ethics.
As with many such methods of beating the casino, whilst it is technically entirely legal, any player found to be exploiting it is almost guaranteed to get politely ejected from the casino at best. And at worst they can expect to be ejected in a fashion most impolite and then barred from that casino and other partner or neighbouring establishments.
Anyway, before we start evoking scenes from Hollywood’s gangster-rich portrayal of casinos, let us explain what wheel bias is. We’ll look at how and why it might come about, if it really exists in any meaningful way and whether or not it is applicable to online roulette, be that of the Random Number Generator (RNG) type or in a website’s live casino suite.
What Is Roulette Wheel Bias?
Most casino games are described as games of chance as opposed to games of skill, and the key difference between the two in simple terms is that the former rely solely, or at least primarily, on luck, whilst the latter can be influenced by the skill, ability or actions of the player. Roulette is very much a game of chance and like other such games it uses what is sometimes called a randomising device in order to determine the outcome.
The randomising device is what makes the game one of chance – luck, rather than skill – and is designed to deliver random, unpredictable results. The device used can be dice, a pack of cards or, in the case of roulette, the spinning wheel and ball. But if the wheel doesn’t serve its purpose and doesn’t deliver random results the casino may have a very large problem, whilst the savvy punter may be able to cash in.
When a wheel is no longer functioning correctly as a randomising device, by which we mean the numbers the ball is settling in are not sufficiently random, then wheel bias is said to exist. Perhaps we can understand this more clearly if we think about dice for now, rather than a roulette wheel.
It is possible to obtain weighted dice that are not perfectly balanced and so, rather than each number from one to six having an equal chance of hitting, they favour one particular number, usually the six. The degree of weighting varies, from novelty items that will always land on a six and are obviously weighted to more subtle ones where a six is much more likely than the other numbers but not guaranteed.
Wheel bias is essentially the roulette equivalent of weighted dice. So whilst each number should have the same chance of coming up, one in 37 in the case of European/French roulette and one in 38 for US double zero roulette, on a biased wheel a certain number (or sometimes section) of the wheel will hit more often. Equally other numbers or areas of the wheel will land less frequently than would be expected were the wheel entirely fair and random.
We should point out that whilst weighted dice are deliberately biased, there is no suggestion that wheel bias is created intentionally. Certainly it is not something you need to worry about in terms of the casino intentionally using non-random wheels. This is because any deviance away from wholly unpredictable results can only favour the punter and so casinos do everything in their power to ensure that wheels function correctly.
Why Does Wheel Bias Happen?
First of all, wheel bias can only occur when a real, physical wheel, ball and croupier are being used. It is not relevant to “normal” online casino roulette, where the graphics you see are simply computer generated. In this version of roulette, the randomising device is not a genuine roulette wheel but a random number generator (RNG). We will look at this in more detail, as well as the relevancy of wheel bias to online roulette, later in the article.
For now, let us return to the issue of what causes wheel bias on an actual “real world” roulette wheel. Wheels can become insufficiently random for a range of reasons but in truth wheel bias is less common than it used to be due to improved manufacturing processes and testing. Modern wheels are actually impressive feats of precision engineering and the vast, vast majority of the time they are uniform and made to perfection so as to ensure bias never happens.
What’s more, biased wheels are more likely than ever to be spotted by casinos due to the data analysis undertaken by casinos. None the less, from time to time wear and tear (be it tiny almost imperceptible chips, the build-up of dirt, dust or grease or the loosening of some part of the wheel), or alternatively very minor manufacturing defects, will cause a wheel to deliver the ball to one number or section more often than to others.
The most common causes of bias are:
- Pocket size – a perfectly made wheel has slots for each number that are exactly the same size. However, very small differences due to ever so slightly imperfect manufacturing can mean some are fractionally larger than others and therefore an easier target for the ball
- Deadening – build-up of dirt or oils, or tiny scratches and similar degradation increase friction on the ball, making it more likely to land in certain sections or numbers than others
- Loose parts – general wear and tear can lead to very slight loosening of parts such as the dividers between numbers. Once again this increases friction and deadens the impact of the ball, making it more likely to stop in a specific location
- Uneven wheel – the wheel and the rotor that turns it must be perfectly aligned, with the wheel exactly horizontal otherwise gravity will impact the roll of the ball in a non-random fashion
There are other factors that may cause bias, such as sunlight, atmospheric conditions, some unseen defect causing an uneven slowing of the wheel and so on. However, knowing wheel bias exists and what might cause it is one thing, but can it actually be spotted and exploited?
How To Spot Wheel Bias
The truth is that these days spotting wheel bias is almost impossible. Most bias is caused by very tiny imperfections and the bias created is correspondingly small. You are not going to see a wheel, for example, that spins a given number every spin, or every other spin. You aren’t even going to see it hit every 20 spins, almost twice as often as would be expected, because even then such a relatively obvious bias would be quickly picked up by the casinos.
Many seek to identify a bias using pure statistical analysis of the numbers but you need to consider a huge number of spins for such a method to be valid. You can watch a wheel and see number 33 come up four times in a row, or a certain sector 15 times in a row but this is not, almost certainly, due to bias, but it is simply natural variance.
In order to be sure that a wheel is biased you would want to analyse many hundreds of spins and ideally several thousand. That takes levels of patience and commitment few possess, even if they have the ability to do so. And of course you also have to be sure that it is exactly the same wheel, rotor and base, in the exact same position of the casino.
Then once you have done all that, even if you have found a wheel bias, you have to ask whether or not it is big enough to overcome the house edge, which is worth at least 2.7% (depending on which version of roulette you are playing). Nobody said this was going to be easy – although people have proved it can be done!
Perhaps an easier way to spot wheel bias is to physically see its impact. In order to do this you would need to be able to watch the ball and wheel very closely and also be something of a roulette expert. However, if you have watched enough spins it is certainly possible to become aware of a ball, pocket, sector or wheel that is behaving slightly differently, be that the ball not bouncing quite as much or the wheel slowing down in a certain rotational position a little more.
Once again though, this is far from easy because, of course, if it was so obvious, the croupier, supervisor or pit boss would also spot it.
Can The Croupier Control The Result?
One potential element of bias we have not yet discussed is the croupier. Although a roulette wheel is designed to be as random as it can and introduce as much chaos theory into proceedings as possible, the croupier is a constant. How they spin the wheel and introduce the ball is down to them and so many have wondered whether or not it is possible for the croupier to control where the ball comes to rest.
Whether intentionally or otherwise, there are those who argue that the croupier can deliver the ball to a certain area of the wheel more frequently than another sector. There is some debate over quite how possible this is and quite how reliable it is, but the general consensus is that the concept of a “dealer signature” is indeed valid.
Basically the argument goes that some casino staff have such a consistent method of doing their job that that the wheel speed and ball speed are almost the same every time. With the further possibility that they will introduce the ball in roughly the same place each time too – whether subconsciously or otherwise – this creates a “signature” for that croupier.
Nobody seriously argues that a croupier can land a certain number with any degree of accuracy. However, the signature may cover a grouping of four to eight sequential (in terms of the wheel) numbers. If we assume that a given dealer’s signature spans six numbers you would expect the ball to land in one of the sequential numbers just over 16% of the time (slightly less than one in six).
If a savvy roulette player identifies that a dealer has a reliable signature and is hitting this grouping, say 30% of the time, then clearly this bias could yield profitable results. Such betting would be entirely legal and of course this is different to a situation where the player and croupier are working together, which would not be legal.
Can A “Normal” RNG Roulette Wheel Be Biased?
Disgruntled customers who have lost, especially if they have seen what they perceive to be an “impossible” sequence of numbers but is actually just natural variance, often claim that online roulette is fixed. However, we are highly confident that all the great sites we work with are 100% legitimate.
They are all independently tested and verified and in particular their RNG software is checked by independent bodies to ensure it is sufficiently random. Whether RNG technology can ever be 100% random is something of a philosophical debate but what matters is that it is sufficiently random, and it is certainly that.
So, whilst there is no wheel bias in the true sense of the term with computerised versions of roulette, simply because there is no real wheel, there is also no “e-bias” in any meaningful sense of the term. If you play online roulette you can be sure that the results really are random, so Lady Luck should be where you pin your hopes rather than any attempt to uncover a bias of any sort.
So Wheel Bias Is Irrelevant To Online Roulette?
Well, not so fast. Whilst traditional online roulette uses an RNG, all good casino sites also offer live casino games, including live roulette. These offer a truer, more immersive casino experience and use real croupiers and real wheels via live video streams. In theory at least, such wheels do lend themselves to bias and could be exploited by a player who was clever, committed and determined enough.
Whilst it would be hard, if not impossible, to identify any wheel bias at an online live casino using your eyes, a mathematical analysis is perhaps more viable than it would be at a bricks and mortar establishment. Recording the results of a table and even specific croupiers could be done unobtrusively and methodically from the comfort of your own home in a way not possible at a physical casino.
We maintain that identifying a meaningful wheel bias would be far from easy but there is no doubt that it is theoretically possible.