First off, let’s talk about some of the different types of weight plates available on the market.
Bumper plates tend to be used by those who enjoy high impact training such as weightlifting, undertaking movements like the clean and jerk and have also been gaining popularity amongst the crossfit community.
Often made from solid rubber they have a metal collar in the centre that ensures they fit on to an Olympic barbell. Whilst they offer advantages being made of rubber this doesn’t make them unbreakable. Given the abuse they tend to take when being dropped overhead on to, sometimes, a solid floor more inferior bumpers can begin to crack around the collar resulting in barbell imbalance when resting on the floor.
Bumpers are noticeable in that they are generally always the same diameter with only the thickness changing. Popular, because they are easy to handle and, not being made of iron, they make far less noise when being dropped.
The weight accuracy of bumpers is commonly around 2 to 3% either above or below the plates stated weight and can, in more extreme cases, be as much as 10%. When using these plates you’d be unlikely to notice the difference unless you were utilising a large number of plates at any one time when the weight difference could begin to stack up.
STANDARD WEIGHT PLATES
These are great for home gyms and beginners who are using less weight. They are generally manufactured from cast iron with a 1” diameter centre hole meaning they wouldn’t fit on your Olympic barbell.
They are cheaper than most other plates and made using a cast iron mould where the finished plate is then completed with a powder coating or rubber coating.
Unlike bumpers they vary in both diameter and thickness. As with the bumper plates, the plate accuracy can be off by a few percent but as with bumpers this tends not to be noticeable when lifting a lower amount of weight.
OLYMPIC WEIGHT PLATES
The most popular kind of plates for gyms, they are manufactured with a 2” diameter centre hole meaning they’ll fit Olympic bars along with most other commercial barbells and plate loaded equipment.
They are made from a variety of different materials and available in cast iron which can be coated with either rubber or urethane. The rubber and urethane coating tend to be more popular than bare iron as they offer extra protection against floor damage with the urethane being a better quality coating which would last longer.
Calibrated plates are typically used by those lifting significant amounts of weight in a competition environment or those in professional or elite sports environments.
There are two types of calibrated plates, those made from cast iron and those made from machined steel.
Cast iron plates are usually made with a sand cast mould. Once cast, the plates typically have two ‘pockets’. The pockets are filled with lead, the lead is what helps the plate to attain its required weight. The finished plate is then powder coated, usually to the colour corresponding to its weight i.e. red to indicate 25kg.
Machined steel plates are machined using a lathe from a solid steel disc. They are machined to accuracy so don’t require any additional materials to be added. In respect of the Kustom Kit Calibrated plates, we then finish them with a nickel plating so they are not open to the elements and susceptible to rusting.
When it comes to the accuracy, calibrated plates are very precise and the weight of each plate needs to come in at 0.25% or 10 grams (whichever is lighter). You may also notice that calibrated plates are marketed as being thinner than plates such bumper and Olympic.
SO WHERE DO THE BENEFITS OF CALIBRATED PLATES COME IN?
As an example, if you’re simply loading a 25kg bumper plate on each side of your barbell you wouldn’t necessarily notice any weight imbalance when squatting, benching or deadlifting. However, if you load four 25kg plates on each side you’d expect to be lifting 200kg (excluding the bar and collars). The reality though is there could be a significant difference:
Based on a 3% accuracy of each 25kg bumper plate the total weight could vary between 194kg and 206kg, split unevenly across your barbell.
As a worst case scenario, based on 10% accuracy of each 25kg bumper plate, the weight difference could be as much as 180kg to 220kg, again split unevenly across your barbell.
This would be very noticeable when lifting! Essentially, accuracy becomes more important with the more you lift.
If you load 200kg of calibrated plates on your barbell, then you’re lifting 200kg pretty much on point.
When it comes to the thickness of the plate, the advantages are again noted by those who lift large amounts of weight.
When the plates are thinner it enables the user to load more plates on to their barbell and keeps the weight nearer to the centre of the bar. This is beneficial for squatting and deadlifting as keeping the weight close to the centre means less bend on the bar and less whip. Less whip means that the user remains more stable thus making it safer.
Consider the kind of gym members you have and how they lift. If many lift big numbers then calibrated plates could be a worthwhile investment.