Everyone knows that the house has the edge in roulette. If you didn't know this, you should do. All casino games have a house edge- this is the "tax" you pay the casino so it can run its business. Some people win at roulette, some people lose, but on average, over say a month, the house wins.
This house edge, or house advantage is around 2.6% on European Roulette (it can go down to 1.3% on some French roulette tables), or 5.2% in American Roulette. That is to say, if you added up all of the bets made by all of the players over the day in a casino on their single zero roulette table (European), the house would be 2.6% up. Lets say all the punters bet £100,000 during the day. The casino would pockets £2,600 on average.
That's not to say that casinos don't go into the red sometimes. They do, even if you average out the day. But can the advantage or edge ever move in the favour of the player?
Well, that is where we come on to the subject of biased roulette wheels. This can only ever happen on a physical wheel- so you would have to be playing roulette at a land-based casino, or playing live roulette online, rather than video roulette, which will always mimic a perfect wheel with no imperfections (it would be great if they copied imperfect wheels, wouldn't it!). Try the Titanbet live roulette tables for instance- they have a wide range of tables. There´s been plenty of books written on the subject- the Perfect Bet, for example.
Physical wheels are manufactured, and no wheel will be 100% perfect. Some may have more imperfections than others. The wheel has to be mounted on the table on bearings, and it has to be mounted on the level. Again, there is scope for an imperfect mount and a biased roulette wheel. There have been cases historically where players have been able to identify biased roulette wheels (no easy task), and then map out hot zones on that wheel that have given them a significant advantage over the casino. Some teams use roulette computers to help them get that edge, others look for patterns by eye.
A biased wheel is one with a defect - certain numbers or sectors of numbers- will drop in more frequently than others.
Types of bias
The pockets on the wheel can be manufactured slightly differently, or they can evolve into having different properties through wear and tear. This may make it harder or easier for the ball to settle in certain pockets. One pocket could be slightly bigger than the others, for example. The edge of the pockets may become worn, resulting in the ball having a slightly different reaction to it when hit.
Hot sectors can start appearing if the wheel rotor becomes worn and starts to wobble (rotor wobble). The axis of the wheel can become slightly bent (we are talking small imperfections here) wobble. The ball track at the top of the wheel (where the croupier launches the ball, spinning it in the opposite direction to the roulette wheel) can also be subject to wear and tear- some sectors may scratch and build up more friction than others, for example.
Any of these defects on their own may not make much difference, but add 3 different defects together, and it may start to become significant.
How do You Spot A Biased Wheel?
OK, so we have established that wheels can be imperfect and have defects, either built into them at the time of manufacture, or that develop through wear and tear. How do you spot a defective roulette wheel?
A wheel wobble is relatively easy to spot. Look for reflections of lights in the wheel. If the reflection is wobbling, chances are that the wheel is wobbling. The other types of defects are difficult to spot without the help of technology (and you'll be thrown out of the casino if you try and measure imperfections with any form of sophisticated technology).
Other factors that come into play include the dealer, the rotational speed of the wheel (some of these defects are more prominent at different speeds. Have you ever "driven through" a wheel wobble in a car with unbalanced tyres by increasing your speed? The theory is the same). The ambient humidity and air pressure will also affect how the ball moves around the wheel.
Time of the day
The rotor speed
How the wheel is oriented
You are also up against the casino, which is studying all of these things and tracking them from the other side of the table. They are working on minimising all this stuff, so for example they may move the wheels around the casino to make it harder to spot individual wheels (try and identify unique scratches and ID marks if you can). Here's a fascinating article on the subject by Jeff Murphy, the Director of Table Games for Seven Feathers Hotel & Casino Resort in Canyonville, Oregon.
Professional wheel bias players will spend days just watching the wheels, without making any bets at all, or at least making low value infrequent bets. Biased wheel spotting is perhaps the most difficult part of the "roulette system" for them.
Laurance Scott is perhaps the most famous player with thoughts on this subject of "Visual Ballistics" and ball tracking. His "crossover pattern method" attempts to estimate how many spins remain before the ball drops onto the wheel and to predict which zone the ball will land, depending on a, observed "crossover pattern". He claim an optimum speed of rotation for biased wheel players is around 2 seconds per revolution.
How Do You Bet on a Biased Wheel?
Well, the whole key to these biased wheel systems is in identifying hot sectors and zones. How big these zones will be will depend on how biased the wheel is, the speed of rotation, the initial ball speed and so on. One a hot sector has been identified, it is then a question of making a number of single number (straight up) bets that cover this sector, (through a custom bet) and then praying that ths sector comes up more often than it should do. In sophisticated tracking systems, the zone will change from spin to spin, but you'll need some pretty sophisticated technology to do this.
The betting bit is relatively easy, it's the biased wheel identification and then the hot zone identification that is the difficult bit.