If you’ve been wondering how do adjustable dumbbells work? You first need to understand that there isn’t just one type of adjustable dumbbell. There are four popular types of adjustable dumbbells, Twist locks, pin selectors, dial selectors, and the old-school spinlocks, plates, and bars.

All Types have their advantages and drawbacks, which we’ll look at today. And I’ll explain how each adjustable system works.

First: Why Choose An Adjustable Dumbbell?

I’ve been using adjustable dumbbells for over 20 years; they are still the most used bit of kit in my home gym. If your workouts require fast weight changes, an adjustable dumbbell is a must.

The speedy adjustment times of adjustable dumbbells allow you to perform any advanced or basic bodybuilding technique, even drop sets that require the fastest of weight changes. Still, it’s not just the speedy adjustment times that make the adjustable dumbbell so appealing. They also save a ton of space. A set like the Bowflex replaces 15 sets of fixed-weight dumbbells. That’s a heck of a lot of space to save especially if space is tight in your home gym.

 flybird 25lb twist lock adjustable dumbbell handle

How Do Adjustable Dumbbells Work? Top 4 Systems Explained and My Fav.

Space saving designs and speed are the two most impressive features of an adjustable dumbbell, but before choosing one, you need to know how each adjustment system works and which one is best for you? Let’s take a close look at the top four adjustment systems on the market, and I’ll tell you why after 20 years of using adjustable dumbbells, I have a favorite.

core fitness twist lock adjustment system

1. Twist Lock Adjustment System

We start with the fastest adjustment system out there, the twist-lock adjustment system. The twist-lock adjustment system works by twisting your wrist to the desired weight you want to lift. When you twist your wrist, the adjustment system locks into the weight plate you want to pick up. For the smoothest weight changes, always remember to sit the dumbbell fully in its storage tray first.

I’ve used and reviewed every adjustment system available, and I’ve always found the twist-lock system the easiest and fastest to use. It can be done with one hand and takes just a second to adjust. The speed and ease of use is why it’s my favorite of all the adjustment systems.

If you want to get hold of a set of twist-lock dumbbells, the Core Fitness Adjustable Dumbbells are the most impressive 50lb per dumbbell set. Priced at $350 for two dumbbells. This is an excellent price for a 50lb per dumbbell twist lock set.

However, if you’re a beginner, there’s a range of cheaper twist lock 25lb per dumbell sets available. The one I’d recommend is the Flybird Twist Lock 25lb dumbbells. You can choose to buy a single or a pair. The single Flybird Dumbbell is just under $100.

Bowflex dial select system

2. Weight Selection Dial

The weight selection dial or dial selectors were the first fast-to-adjust systems to hit the market nearly two decades ago.

The selection dials are easy to use. All you need to do is turn the dial which is usually on the end of the dumbbell handle, to the amount of weight you want to lift.

Some dial selection dumbbells use two dials. If an adjustable dumbbell uses two selection dials (one either end of the dumbbell), this typically means the dumbbell adjusts in small weight increments. Small weight increments are a good thing, especially for beginners, and isolation exercises.

The most popular Selection Dial Adjustable Dumbbell is the Bowflex 552. The Bowflex 552 adjusts in small 2.5lb increments, which is why it has two dials. Two dials will give slightly slower adjustments times, but because The Bowflex boasts smaller weight increases, it makes the Bowflex Dumbbell appealing to both beginners and more seasoned lifters.

There are countless other selection dial dumbbells on the market, all of which copied the Bowflex dial system, but most use just one dial, so you don’t have the small weight increases. Nearly all adjust in 5lb or 10lb increments.

lifepro single 25lb pull slide selector adjustment system

Pull-Slide Selectors

The pull slide selectors have become popular lately mainly because they are fast and easy to use, taking just over a second to adjust. Still, it’s my least favorite because it’s not very durable. This system tends to break much sooner than any other adjustments system. It’s the most delicate of all the adjustment systems. It’s one you need to be particularly careful not to slide across too hard when changing the weight, or you’ll break it.

This adjustment system is foolproof and straightforward. You just pull the sector and slide it across to the weight you want to lift. It’s that easy.

The LifePro 25lb Dumbbells are the most popular set for beginners and my favorite of the pull selectors simply because Lifepro builds quality gear. At $69 per dumbbell, they are a bargain for anyone who’s just starting lifting.

A few heavier sets of bells use this system, such as the NordicTrack 55lb Adjustable Dumbbells and the Weider 50lb set.

golds gym dumbbell bars and weight plates

4. Adjustable Plate Loaded Dumbbells

And finally, we go old school. Plate-loaded dumbbells were the very first adjustable dumbbells, and they’re just as popular now as they were 50 years ago. You can pick up a decent set of 40lb plate-loaded dumbells for around $50, and the low price tag is the main reason this type of adjustable dumbbell is so popular.

Weight changes are more time consuming because you have to take on and off the plates. And to do that, you must unscrew the collars on either end of the dumbbell handle, which takes time. So you won’t be able to perform a few advanced bodybuilding techniques. However, the durability of an old-school set easily makes up for the slow adjustment times.

These things are all metal. You can throw them around, drop them on that last killer rep, and they’re not going to break. If you tried that with any of the fast-to-adjust dumbells, they’d all break, and you’d end up with a hefty repair bill because drops aren’t covered in the warranty.

So yes, the old school sets still have a lot going for them. The price is great; you can lift more-anything from 5lb to 200lb so great for beginners and serious lifters, plus they’re super tough. If you don’t mind the slow adjustment times? A set of iron plates and bars might be your best choice!


A Few More Tips on What To Look For When Choosing An Adjustable Dumbbell

We’ve covered all the adjustment systems out there and how they work, but there are still some other important things you should consider when choosing adjustable dumbbells, and I’ll quickly go through them for you.

Weight Increments

Small weight increases are one of the keys to progress no matter what apparatus you’re using or what exercise you are performing, and ideally, for dumbbells, you need 2.5lb increments or 5lb at the highest.

Large weight increments will make you cheat on your form, cause injury, and slow your progress. Think of it this way if you can curl a 20lb dumbbell for ten reps and you want to keep adapting, curing a 25lb dumbbell represents a 25% increase in load. That’s a large jump, even for seasoned lifters.

However, if you purchased a dumbbell that adjusts in 10lb increments like so many beginners make the mistake of doing, that jump now represents a 50% increase in load, which is too big a jump for anyone. 10lb increments are almost useless for bodybuilding, and isolation exercises.

If you want to progress properly with your dumbbell lifting at home, always choose an adjustable dumbbell with small weight increments. 5lb at most. 2.5lb is best.

bowflex 552 2.5lb weight increments

Fixed Length Handles Can Be Awkard To Lift With

Another issue that affects many of the selectable sets of dumbbells induing popular sets like the Bowflex are fixed length handles. A fixed-length handle is a handle that stays the same length no matter how much weight you are lifting. It doesn’t matter whether you’re lifting 5lb or 50lb the length of the handle stays the same.

Long handles (fixed length) can be awkward to lift with, especially when setting up for presses and curing. When pressing, they can clash above your head and hit your sides when curling. I wouldn’t say they are a deal killer, but if you’re a beginner, a long handle adjustable dumbbell can take a few weeks to get used to.

The good news is there are a few compact adjustable dumbbells on the market with sets like the Core Fitness Twist Locks that boast handles that only get longer with the more weight you add. This makes for a compact dumbbell, which feels natural to lift with. So if you can, look for a compact adjustable dumbbell one that doesn’t include a fixed length handle.

If you’re a beginner and thinking of purchasing a lighter 25lb adjustable dumbbell? You don’t have to worry so much if the dumbbell you chose has a fixed-length handle as 25lb dumbbells, in general, are much shorter than the fixed-length handles of the heavier sets because there’s less weight.

How much Plastic Is Too Much?

And lastly, plastic. It seems unavoidable that if you want a fast-to-adjust dumbbell and you don’t want to pay over $500 for a heavy-duty version? You’ll have to live with some plastic in the design of your dumbbells. Apart from the old school sets, most adjustable dumbbells will have plastic in the handles and adjustment systems. Some even have a plastic casing around the iron-weight plates.

What does all this plastic mean for your workouts? You have to be careful not to drop one because drops aren’t covered in the warranty of any selectable dumbbells.

This also means no training to failure and dropping the dumbbells on your last rep. I recommend no drops from height at all. Most will survive drops of 6″ or so, but I wouldn’t risk any higher.

However, I wouldn’t let plastic put you off from buying an adjustable dumbbell. There’s always been some plastic in the fast to adjust sets. It’s nothing new. You can buy more expensive all-metal sets like the Snode Adjustable Dumbbells or NÜOBEL’s which can handle drops and are fast to adjust, but they cost twice as much as anything else. And they aren’t worth their high price tag, in my opinion. Stick to sets like the Core Fitness, Bowflex, or Powerblock Elites, which all cost under $500 for two 50lb dumbells, and if you’re a beginner who only needs a 25lb dumbbell? The Flybird 25lb adjustable dumbbell is your best choice.