DUMBBELLS - A TECHNICAL GUIDE

November 06, 2021 21 min read

What types of Dumbbells are there?

Contents

A TECHNICAL GUIDE TO DUMBBELL TYPES

As a manufacturer of Custom Dumbbells, we were fed up with the lack of clarity surrounding the different types of dumbbells with articles pumping out information that was misleading and factually incorrect. We set about creating the ultimate guide to the different types of dumbbells, the dumbbell coatings, grip variations, shapes, and sizes plus much more! Use the contents above to skip to the relevant section

Dumbbells come in a huge variety of shapes and sizes ranging from small 1kg/2.2lb dumbbells all the way up to 100kg dumbbells, it is not unheard of to hear of Custom Dumbbells which weigh 150kg/330lb!

Dumbbells come in a huge range of colours and materials, some are made for home gym environments, whilst others are designed for heavy duty commercial use and it’s important to understand the correct selection when looking to add these dumbbells to your gym.

This article will cover the difference in handle grips, size, weight, and their best use.

So let’s get started!

What is a Dumbbell?

As with much of exercise and fitness equipment, the dumbbells origins loosely date back as far as 2000 years, where Greek Spartans carved out stone to form a weight with a handle, this was referred to as a Halter.

This was a large rock with a handle carved out at one end, the halter was used for gaining momentum in the long jump during the Olympic games. Apart from its main use, Spartans often used them in the same way a modern-day dumbbell would be used by performing bicep curls, lunges, and deadlifts.

A dumbbell, when gripped, is designed to add resistance to a movement or exercise performed by the user.

What types of Dumbbells are there?

Dumbbells fall into three distinct groups.  Fixed, Adjustable and Plate Loadable Dumbbells.

Fixed dumbbells comprise of a single grip which is permanently fixed between two billets meaning the dumbbell weight is fixed and cannot be altered.

Adjustable dumbbells consist of a series of weight plates mounted in a base, a mechanical handle or dial is adjusted to select a specific plate and therefore adjust the weight of the dumbbell.

Plate loadable dumbbells consist of a handle which is physically loaded with weight plates and secured using a barbell collar.

Hex Dumbbells
Hexagon
Studio Dumbbells
Round or Hexagon
Custom Dumbbells
Circular
Urethane Dumbbells
Circular
Rubber Dumbbells
Circular
Pro Dumbbells
Circular
 
Circus Dumbbells
Globe
 
Thomas Inch Dumbbell
Globe
 
Strongman Dumbbell
Circular
 
Olympic Dumbbell Handle
Various
 
SpinLock Dumbbell
Various
 
Pepin Loadable Dumbbells
Circular
 
Ironmaster Loadabale Dumbbells
Square
 
Bowflex Adjustable Dumbbells
7 Sided
 
Nuobell Adjustable Dumbbells
Round
 
Power Block Adjustable Dumbbells
Square
 

 

The dumbbells in the table above can be categorised into 3 groups:

Fixed Dumbbells

      • Hex Dumbbells
      • Studio Dumbbells
      • Custom Dumbbells
      • Urethane Dumbbells
      • Rubber Dumbbells
      • Pro Dumbbells
      • Circus/Globe Dumbbells
      • Thomas Inch Dumbbell

Plate Loadable Dumbbells

      • Strongman Dumbbell
      • Olympic Dumbbell Handle
      • Spinlock Dumbbell
      • Pepin Adjustable Dumbbells
      • Ironmaster Adjustable Dumbbells

Adjustable Dumbbells

      • Bowflex
      • Nuobells
      • Powerblock

Now we understand what different types of dumbbells there are and what categories they fall into, we can go in to more detail about what makes each dumbbell different.

Continue reading for more information about the following:

      • Dumbbell Handles
      • Dumbbell Shapes
      • Dumbbell Material Selection
      • Dumbbell Coatings
      • Dumbbell Storage
      • Dumbbell Maintenance
      • Pro’s and Con’s of each dumbbell

Understanding Dumbbell Material Selection

Most dumbbells on the marketplace are produced using two types of steel, whilst there are three types, the third is less common for several reasons as mentioned further on in the article. 

The most popular dumbbell materials are Cast Iron and Mild Steel with the third material, Stainless Steel, being found on less common Custom Dumbbells.

Of the three materials used in dumbbell manufacturing, it is important to pay attention to the following six features of the material

      • Carbon
      • Chromium
      • Nickel
      • Molybdenum
      • Density
      • Hardness

1. Carbon

Carbon is an element found in all 3 material types used to make dumbbells.  However, the amount of carbon varies between material.  Carbon has several effects on the material increasing the strength of it by binding iron atoms together.  Add too much carbon though and the material will then become brittle

As Carbon Content Increases
      • Hardness Increases
      • Brittleness Increases
      • Tensile Strength Increases
      • Rate of Corrosion increases
As Carbon Content Decreases
      • Ability to weld item reduces
      • Rate of Corrosion decreases
      • Hardness Decreases

2.Chromium

Chromium is a hard and corrosion resistant atom only found in stainless steels. Chromium is added to stainless steel at a minimum rate of 10.5% making it the best dumbbell material to use for those who are using dumbbells outside or in high humidity areas such as swimming pools or in areas close to seawater.

While chromium does react with oxygen and corrode it does so on an atomic level which is not visible to the human eye. As the chromium corrodes it forms a tight layer which then protects the steel underneath from corroding, the higher the chromium level, the thicker the layer.

As Chromium Content Increases
      • Corrosion resistance increases
As Chromium Content Decreases
      • Corrosion resistance decreases

3.Nickel

Nickel is added to Stainless Steel materials to perform two main functions. To increase corrosion resistance whilst also improving hardness.  As Chromium levels increase, corrosion resistance rises however Chromium reduces the hardness of the stainless steel, this is offset by the addition of Nickel

As Nickel Content Increases
      • Corrosion resistance Increases
      • Hardness Increases
As Nickel Content Decreases
      • Corrosion resistance Decreases
      • Softness Decreases

4.Molybdenum

Molybdenum is a large atom only found in 316 stainless steel Custom Dumbbells.  This type of dumbbell is rare because of the high material cost and difficulty to machine.  Molybdenum is added to 316 Stainless steel to improve its hardness and resistance to wear making it perfect for highly corrosive atmospheres.

316 Stainless steel can often be found at beaches, in swimming pools, chemical processing equipment, boats and even in jet engines!

5.Density

Material density is measured in centimetres cubed (cm3) and provides us with the density of steel which would be found in a cube measuring 1cm long x 1cm wide x 1cm high.

Higher densities are important when manufacturing dumbbells as it enables the weight to stay more compact and easier to handle.

6.Hardness

Hardness is important for dumbbells which do not have a coating such as rubber or urethane as the surface is exposed.  Hardness is measured in Brinell. The higher the Brinell number, the harder and more resistant the material is to permanent deformation. Of all the materials, mild steel is the hardest and, depending on the grade, can reach a huge 429+ on the Brinell hardness making it over twice the hardness of 316 Stainless Steel.

 

Likely to Rust

 

Unlikely to Rust

 

Cast Iron

EN8 Mild Steel

303 Stainless

316 Stainless

Carbon Content

2-4%

0.36-0.44%

0.0 - 0.10%

0.0 - 0.07%

Chromium

0

0

17.00 - 19.00

16.50 - 18.50

Nickel

0

0

8.00 - 10.00

10.00 - 13.00

Molybdenum (Mo)

0

0

0

2.00 - 2.50

Density

7.35 g/cm3

7.85 g/cm3

8.03 g/cm³

8.00 g/cm³

Hardness

179-202 Max Brinell

201-255 Max Brinell

230 Max Brinell

215 Max Brinell

 

The Three Types of Dumbbell Materials

Cast Iron

Cast Iron is a magnetic material that is manufactured by first taking iron ore, which is a mineral mined from rocks.  There are four types of iron ore, but the most common used in cast iron production is hematite.

The iron ore is melted in huge furnaces whilst being mixed with up to 25% scrap metals and other alloys to form a liquid metal. As Cast Iron is an alloy containing up to 4% carbon it has a high viscosity making it easy to be poured.

Cast moulds are produced of the dumbbell which are then split in half and placed into a box

Those boxes are then filled and packed tightly with a mixture of sand and oil to give a good impression of the dumbbell. The mould is then removed from the sand leaving a cavity which is then filled with molten iron to form the dumbbell.

There can be a lot of variation when sand casting iron which is why in general cast dumbbells are not particularly accurate, some dumbbells can be up to 3% lighter or heavier than their stated weight.  Unlike mild steel, cast iron cannot be heat treated to improve it’s strength.

Mild Steel

Steel is very similar to cast iron in that it is a ferrous metal.  However, it is a far purer product containing between 0.2% and 1.9% Carbon. The lower the carbon level the higher the grade of steel with steels such as EN16 and EN24 being perfect for heat treatment which improves the strength even further. Steels in this category are magnetic.

Unlike Cast Iron, steel is not brittle and has a higher density meaning dumbbells can be made smaller than their cast iron counterparts as they are less likely to break.

Stainless Steel

Stainless steel Dumbbells can be produced in two variations. 316 stainless or 303 stainless.

There is a variation known as 304 stainless steel and although it offers slightly better corrosion resistance in comparison to 303 it is not a material which is easily machined and is therefore not used in dumbbell manufacturing.

Unlike mild steel or cast-iron, stainless steels have at least 10.5% chromium which reduces corrosion significantly.  The higher the level of chromium, the less the material will degrade.  316 Stainless Steel has a higher nickel content in comparison to 303 or 304 with the addition ofmolybdenum making it even more corrosion resistant.

However, 316 stainless steel is at least two to three times as expensive as 303 stainless steel and six times the cost of mild steel.

Contrary to popular belief, all stainless-steel CAN rust. The rate of corrosion though is far lower than steel or cast-iron alternatives but in an indoor gym environment this is unlikely to ever happen unless your gym is next to the sea or a swimming pool with high levels of corrosive humidity.  

It is easy to test to see if your dumbbell is stainless steel, simply place a magnet on the surface.  If its magnetic it’s not stainless steel.  If it’s not magnetic, there is a high chance you have stainless steel.  Unfortunately, the only way to check if the dumbbell is 316 or 303 would be to perform a chemical test on it so unless you are willing to do this you must have a trustworthy supplier.

What are the different shapes of Dumbbells?

Dumbbells come in 4 different variations:

      • Six Sided – Also known as hex dumbbells
      • Circular Dumbbells – The most common cumbbell Shape
      • Spherical – These are globe shaped dumbbells
      • Square – More common on adjustable dumbbells
      • 12 Sided – Less regular these offer a balance between hex and circular

Six Sided Hex Dumbbells

Six sided dumbbells, also known as Hex Dumbbells, exist to provide more stability during workouts and are typically found in home gym’s or Crossfit Box Gym’s. Hex Dumbbells are commonly made from cast iron and coated with either rubber, urethane or neoprene. Because of their construction and low cost, hex dumbbells are better for individuals that train at home or are on a limited budget.

 These six-sided dumbbells generally come in two styles

    1. Studio dumbbells which are entirely coated in Neoprene, Vinyl or Rubber and are available between 1kg and 10kg
    2. Hex Dumbbells have a knurled handle and only the ends of the dumbbell are coated in either rubber or neoprene and can go from 1kg to 50kg+
    Hex Dumbbell Positives
        • As Hex Dumbbells are mainly made from Cast Iron they are usually cheaper than other alternatives on the market.
        • The Six sides stop dumbbells rolling away during exercises where dumbbells would be placed on the floor such as push ups.
        • The Hex Dumbbell coating protects the dumbbell from scratching or damaging equipment.
        • Because Hex Dumbbells don’t roll, it’s good for those on a budget as you don’t have to use a storage rack.
    Hex Dumbbell Negatives
        • Heavy Hex Dumbbells can be awkward when placing them down as they want to roll to their flat position.
        • Because Hex Dumbbells are produced using Cast Iron and more commonly coated for protection, they are not particularly accurate and can weigh 2-3% more or less than the stated weight which can cause muscle imbalance, especially noticeable with heavier dumbbells. 
        • Hex Dumbbells have a higher chance of breakage due to the use of cast iron rather than steel. Because the dumbbell ends are welded first then coated for protection it makes it extremely difficult to fix them as you cannot get to the broken area without taking the coating off.  Meaning when they break, they need replacing. 
        • Hex Dumbbells have slightly higher centrifugal forces surrounding the dumbbell handle which is dependant on where you grip
        • Limited options such as no revolving grips and they are not available in stainless steel finishes due to mass production.
        • They cannot be stored in traditional dumbbell racks and require flat shelves to store the dumbbells.

    Circular Dumbbells

    Circular dumbbells are the most common shape of Dumbbell on the market. They can be made from Cast Iron, Mild Steel or Stainless Steel.

    Circular dumbbells come in a range of styles and sizes. Circular dumbbells are usually cast in a mould, or they can be machined on a lathe.

    Circular Dumbbell Positives
        • When exercising with circular dumbbells it does not matter how they are placed they will never move as the weight is spherical.
        • Centrifugal forces are the same all the way around the dumbbell handle no matter where you grasp the handle.
        • Circular dumbbells can achieve more accurate weights when machined using a lathe.
        • Available in a wider range of finishes, handle diameters and shapes.
    Circular Dumbbell Negatives
        • Circular dumbbells can roll on uneven floors making them a hazard in certain training environments.
        • Because circular dumbbells are round it is not advisable to keep them on the floor, a specific dumbbell storage rack and saddle would be required to safely store them.  However, this not only adds additional cost but the plastic saddles can break when heavy dumbbells are thrown into the rack after a heavy workout.

    Globe or Circus Dumbbell

    The Globe shape is found on the circus dumbbell. This type of dumbbell is not common in home or commercial gyms and is usually found in functional training environments such as strongman. Circus dumbbell ends and handles are generally larger in diameter in comparison to other dumbbell types.

    These dumbbells are generally used in single arm movements such as the overhead dumbbell press.

    Globe Dumbbell Positives
        • Rounded globe dumbbells are better for overhead pressing as your forearm can rest against the dumbbell end more comfortably thanks to its rounded edge.
        • They can promote better balance and grip strength due to the huge size.
    Globe Dumbbell Negatives
        • Far harder to grip.
        • Cannot be used the same as a traditional dumbbell.
        • Not available in light weights, mainly because of its intended use.
        • Harder to press. People generally press overhead from the side of the shoulder or sitting on top of the shoulder.
        • Limited variations in design of circus dumbbells.

    Square Dumbbells

    Less common are square dumbbells. Mostly square dumbbells tend to be adjustable. Examples of this are the Powerblock Adjustable Dumbbells or Ironmaster Quick Lock Dumbbells.

    All square dumbbells that are on the market, as is our understanding, are made from cast iron.

    Square Dumbbell Positives
        • These dumbbells will not roll making them safe in home gym environments.
        • They do not require expensive Dumbbell Racks or Storage.
        • More stability over Hex or Octagonal Dumbbells.
    Square Dumbbell Negatives
        • Unbalanced design, the weight is not spread concentrically around it’s centre.
        • You have to place the dumbbell down on its flat side, if you drop it on it’s edge its likely to jerk into position.
        • Cannot be stored in a standard dumbbell rack much like the hex dumbbells and would most likely be suited to a kettlebell style rack which are not rated to as high a capacity as a dumbbell rack.
        • As these dumbbells are less common they have less variations and custom options.

    Octagonal or Dodecahedral Dumbbells

    Octagonal (8 sided) or Dodecahedral (12 sided) Dumbbells are not particularly common in gyms. These dumbbells are usually cast iron and encased in a specialist coating such as rubber or Urethane.

    They provide some of the benefits of round dumbbells whilst avoiding some of the pitfalls of Square or Hex Dumbbells.

    Dodecahedral/Octagonal Dumbbell Positives
        • These dumbbells are less likely to roll like a circular dumbbell.
        • Because of the multiple small edges, they aren’t as likely to jolt if they are placed down on one of the 8 or 12 corners.
        • As each of the edges are so small it can be used in a standard Dumbbell Rack with saddles.
    Dodecahedral/Octagonal Dumbbell Negatives
        • Because the dumbbell has edges, it is more likely to damage the dumbbell saddles in a rack.
        • These are less stable when comparing them to Hex or Square dumbbells and can still roll.
        • Limited choices in materials or handle designs.

    Dumbbell Coatings

    Dumbbells come in a variety of finishes, ranging from synthetic Polyurethane coatings, through to Zinc and Nickel, which are naturally occurring metallic coatings. Each of the coatings are applied using different processes and offer different protection levels and finishes

    Urethane Dumbbells

    Polyurethane also known as Urethane is considered one of the best coatings in the industry for dumbbells. Urethane protects the base metal from corrosion and moisture forming a smooth covering.  A good way to tell the difference between this coating and rubber is that it feels a lot harder to the touch when compared to rubber

    Urethane positives
        • Highly Impact Resistant
        • Waterproof
        • Hard material
        • No smell
        • Reduction in Bounce
        • UV Resistant
        • 50+ Year Lifespan
        • Safer than Steel Alternatives
        • Easier to clean the rubber dumbbells as it’s a smooth surface
    Urethane Negatives
        • More Expensive
        • Do not look as high quality as chrome dumbbells
        • Less accurate than steel dumbbells
        • Difficult to repair if they break

    Rubber Dumbbells

    Rubber is a natural product that is quite often found on dumbbells. It’s quite common to see the debate Rubber Dumbbell vs Urethane Dumbbell when you search the internet.  Although rubber is inferior to urethane, it is highly recyclable and delivered at a more economical price compared to its urethane equivalent.

    Rubber is a natural product harvested from rubber trees with the main producers of rubber being Thailand and Indonesia followed closely by Vietnam, Africa, and then China.

    Rubber Positives
        • Because of their soft texture rubber is considered one of the safest coatings for dumbbells.
        • Rubber is recyclable making it an environmentally friendly option.
    Rubber Negatives
        • Recycled rubber (Non Virgin Rubber) has a very strong odour.
        • Short life span when compared to Urethane but more durable than steel finishes such as Nickel or Zinc.
        • Very difficult to repair if they get damaged or break because of the rubber coating.
        • Less accurate weight than their steel counterparts.
        • Very hard to clean because of its textured surface.
        • Rubber can mark equipment when it’s dropped.

    Nickel Dumbbells

    Steel Dumbbells which are machined using a lathe are normally left bare. Without any form of coating they would rust and corrode so Nickel is a finishing option added to the higher priced dumbbells such as Custom or Personalised Dumbbells

    As you can see from our section on material selection, Nickel makes up almost 10% of rust resistant materials such as stainless steel. Nickel is a hard metal which is applied to the dumbbell by electroplating (there is an electroless version but this is not decorative in its appearance).  A copper base is applied to the metal followed by Nickel in Ultra Thin layers of approximately 13 to 20 microns (0.013 - 0.020mm thick).

    For mineral based protective coatings, we can use the Mohs scale which tests hardness with a rating from 1 through to 10 with 10 being the hardest and 1 being the softest. Nickel is a level 4 on the Mohs scale.

    Nickel Positives
        • Nickel is a highly reflective material giving you a consistent luxurious finish.
        • Unlike Zinc coating, Nickel does not degrade or breakdown and acts as a barrier between the metal and the environment.
        • Because it is extremely thin it is easier to obtain accurate weights and tolerances.
        • Easy to repair these dumbbells when they get damaged.
        • Long life span if looked after correctly.
    Nickel Negatives
        • It is a difficult finish to achieve consistently.
        • It is a costly process which is why some dumbbell manufacturers use zinc plating instead of Nickel.
        • If the Nickel Coating is chipped or removed, the underlying surface can corrode if not kept dry.
        • Nickel coated dumbbells are louder than rubber or Urethane alternatives.
        • Steel Dumbbells can dent and mark unless they are heat treated.
        • More expensive than other dumbbell finishes.
        • This material can be scratched but to a lesser degree than Zinc.

    Zinc Dumbbells

    At first glance Zinc Dumbbells look very similar to Nickel Plated Dumbbells.  However, there are some very big differences. Nickel is applied as a coating that sits between the external environment and the base metal.

    Zinc plating is achieved in a similar way where the dumbbells are suspended in a chemical solution and using positive and negative electrical currents the material, in this case zinc, is drawn to the metal.  Zinc plating is thinner than nickel and deposited around 5 microns (0.005mm thick).

    Zinc Plating is designed to sacrifice itself, breaking itself down to protect the steel underneath. Over time Zinc plating will first start to go black and after a period of time will eventually disappear exposing the bare metal beneath.  

    Zinc is softer than Nickel and is a level 2.5 on the Mohs scale.

    Zinc Positives
        • Lower Cost
        • Offers a reasonable level of rust protection
        • Easy to repair dumbbells when they get damaged
        • Does not chip or flake off as it chemically bonds with the Dumbbell Steel

    Zinc Negatives 

        • Will sacrifice itself and breakdown over time resulting in rust and discoloration
        • Shorter lifespan in a sweaty gym environment
        • Not as bright a finish as Nickel
        • Does not offer the same protection as Rubber or Urethane
        • Not resistant to scratching so will mark much easier 
        • Regular wiping with cleaning solutions will push moisture into the steel resulting in rust

    Enamel Dumbbells

    Enamel is a protective paint layer applied to the dumbbell and most widely used on cast iron dumbbells or weight plates. It consists of a tough paint that adheres to the surface. Enamel is a thick coating and although is available in an almost infinite variation of colours and textures it is most commonly applied to dumbbells as grey or black.

    Enamel is harder than Nickel and achieves a level 5 to 7 on the Mohs scale.

    Enamel Positives
        • Superior corrosion resistance
        • Easy to repair and refurbish
        • Low Cost
        • Very Resistant to scratching
        • Smooth Surface makes cleaning easy
    Enamel Negatives
        • Brittle and can chip
        • Dull Finish
        • No impact protection like Rubber or Urethane
        • It will wear away over time
        • Because of it’s thick coating, it is not very accurate

    Vinyl Dumbbells

    Vinyl, also known as PVC (Polyvinyl Chloride) is a synthetic rubberised substance applied by dip transfer onto the dumbbells. Vinyl is generally applied anywhere from 0.5-5mm thick and is available in a variety of colours.

    Vinyl Positives
        • Soft to the touch
        • Easy to clean
        • Resistant to impacts and scratches
        • Resistant to water
        • UV resistant
        • Thicker Coating than Neoprene
    Vinyl Negatives
        • Some users report the surface being slippery
        • More prone to splitting than Neoprene
        • Not as hard wearing as Urethane or Virgin Rubber

    Neoprene Dumbbells

    Neoprene is a soft synthetic rubber which is applied using a dip transfer. The thickness of the coating is approximately 0.3mm – 0.7mm thick. Neoprene is available in a wide range of colours and is usually only found on lighter dumbbells.

    Neoprene Positives
        • Soft to the touch
        • Resistant to impacts and scratches
        • High Tensile Strength
        • Resistant to water
        • UV resistant
    Neoprene Negatives
        • Higher cost
        • Polymer can crystalize under 10 degrees causing it to become brittle
        • Textured finish makes cleaning harder
        • Thinner Coating than Vinyl
        • Will not stand up to abuse as well as Urethane or Virgin Rubber

    Understanding Dumbbell Handles

    Dumbbell grips form the core of any dumbbell. Length is crucial, too long and the dumbbell doesn’t feel balanced in your hand, too short and the dumbbell ends can interfere with your forearms during certain lifts such as the Flat Chest Press.

    Dumbbell handles can get slightly confusing because of the variations available, from fat grip through to standard grip, knurled or rubber, rotating or fixed. To help differentiate the features of a grip we have broken them down into five main categories

        • Revolving and Fixed Handles
        • Grip Thickness
        • Grip Shape
        • Grip Texture
        • Grip Finish

    Revolving or Fixed Handles?

    Dumbbell grips are produced in two styles

    The first, and most common, is a fixed grip handle where the relationship between the grip and the dumbbell ends are fixed and do not rotate.

    The second style is a rotational grip, like the function of an Olympic Barbell this is where the grip spins separately to the dumbbell ends and is designed to offer less torque on the wrists during movements such as the snatch.

    Fixed Grip Dumbbells

    This type of handle is the king of all Dumbbell grips. Found on most Dumbbells in existence the fixed grip handle has a relationship between itself and the dumbbell end plate that does not rotate. The handle can either be welded into place or mechanically joined using a bolt or fixing to keep the weight ends attached to the grip.

    These Fixed Grips can be Knurled, Smooth or coated in Rubber. They can be ergonomically shaped or be formed with a consistent shape along the entire length of the handle. Fixed grip dumbbell handles can range in diameter from standard and come in a range of diameters to suit every different type of user imaginable.

    Revolving Dumbbell Maintenance           

    To rotate, dumbbells must use either a composite bush or a bearing to reduce friction between the grip and the steel ends and allow them to spin. The main problem with this is that in a gym environment weight gets dropped, quite often from height, resulting in large stresses being placed on the dumbbell components which can easily damage bearings.

    During construction dumbbells are either welded together or mechanically fixed using bolts. A revolving dumbbell which is fully welded will provide the best strength in a gym environment however the problem occurs if the bearings fail as it is almost impossible to get access to the bearing as it is sealed inside the dumbbell. Alternatively, a bolted dumbbell allows you to get access to the bearing to change it, but bolted dumbbells are notorious for working themselves loose which is not great for a gym environment.

    The Revolving Dumbbell Myth

    It appears the appeal of the free revolving dumbbell, and its sudden rise to fame is that it ‘disconnects the weight from the rotational forces of the dumbbell while being used’. While this is true, there are only two exercises in existence that would benefit from a rotating dumbbell

    Those two exercises are

        • Dumbbell Snatch
        • Dumbbell Wrist Curl

    The reason for this is because during both these exercises the angle and relationship between your wrist and forearm changes throughout the movement, on almost all other dumbbell movements your wrist stays completely parallel to your forearm so there is no torsion on your wrist.

    Some manufacturers even claim that the rotating dumbbell handle puts less stress on joints during movements such as bicep curls. We cannot think of a single scenario during a bicep curl where a rotating handle would benefit as the centre of mass (the handle) always stays parallel to your forearm. As the mass stays concentric to the grip on the handle the dumbbell will not spin, and therefore place no torsion on your wrist

    Grip Thickness

    Dumbbell diameter is important as the diameter not only reflects the dumbbell's strength but also the users ability to grip the dumbbell during a workout. Most dumbbells on the market use a standard grip handle however some custom dumbbells offer fat grips as an option.

    Standard Grip

    A Standard grip dumbbell will range from 20mm up to 35mm, diameters under 30mm will almost always be used in light home gym environments. A standard grip will allow you to wrap your fingers almost entirely around the handle until they touch your palms and for your thumb to be placed over your index finger for additional support.

    A grip size between 36mm and 39mm could be classified as either a standard or a Fat Grip dependent on the user that is lifting with the dumbbell. Someone with large hands may feel comfortable at this diameter whereas those with smaller hands may struggle.

    We would always classify a handle diameter 40mm and over as a fat grip. This is because at this point most people would start to find it more difficult to grasp the entire handle under load.

    Thick Grip

    As Fat grips have a larger diameter, they help to develop natural strength in sporting movements where users either tackle, grapple or wrestle.

    They also stimulate muscle growth in the hands, forearms and biceps because the user is at a disadvantage when gripping the weight.

    This happens because, as the diameter of the dumbbell handle grows, the point at which your fingers grasp get closer to the centre of the handle therefore making it harder to grip, meaning you have to stimulate more muscle fibres just to hold on!

    By using fat grips independently, you can try to fix imbalances on lagging body parts by making them work harder. 

    Grip Shape

    The type of grip on a dumbbell can come in two forms, an Ergonomic Grip or a Straight Grip.

    An Ergonomic Grip (sometimes known as a Contour Grip) has a thick central section of handle which gently tapers down at each end, they are manufactured to allow an even distribution of grip across your palm.

    The theory is that our middle finger is the longest while the fingers either side are shorter and therefore would be better suited to smaller diameter handle which is provided with a contoured handle.

    The problem with this is that when you close your grip your fingertips align therefore making the entire purpose of the ergonomic handle futile.

    The main drawback of the ergonomic handle is that they are never fully knurled and most commonly consist of three strips of knurling. One length at the largest diameter and two small strips either side. The reduction of knurling is due to the manufacturing process which only allows knurling to be performed across even surfaces.

    Another downside to ergonomic handles is that they are simply not as strong.

    Because the diameter of the grip is smaller at either end these would produce points of weakness when dumbbells are dropped in a gym environment which could lead to breakage. This could be overcome by carrying out heat treatment to strengthen the bar however this is a costly exercise and would increase the cost of the dumbbell.

    Grip Texture

    Smooth

    A smooth grip is self-explanatory. The handle would offer no texture to assist in gripping the dumbbell. Whilst it is usually coated in a coarse finish such as textured powder coat to increase friction there are only a few reasons why a manufacturer would opt for this type of handle

        • To Reduce Cost – Producing Knurling is a slow and refined process which adds cost to the item
        • Not Required – One of the few movements which normally don’t require knurling is pushing movements as the grip is being forced into your palm rather than pulled away from it
        • Specialist Reasons - The product is designed for children, women or for those who find knurling uncomfortable

    Knurled

    When you have a look at dumbbells, you will notice a textured appearance on the handle. This is what is known as knurling, or diamond knurling, as it forms a diamond shape.  

    To manufacture this, a tool which comprises of two hardened wheels is pressed against a rotating bar which either cuts the steel or forms the material depending on the chosen process.

    When this procedure is carried out, the surface of the bar is altered by producing tiny peaks and troughs and serves two main purposes

        • Increase surface area therefore reducing friction and increasing user’s grip
        • Allow sweat to drain away from the main point of contact

    Rubber

    A rubber grip is used to increase friction and improve the feel of the dumbbell handle. Whilst rubber is one of the best ways to reduce friction, there are a few drawbacks too it: 

      • Sweat is less likely to drain away from the grip
      • It will wear over time therefore increasing the cost of maintenance
      • Rubber is flexible and will change shape when gripped


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