BRAINGAIN Adjustable Dumbbells Review: The 40kg Twist-Handle Set

Twist-handle adjustable dumbbells have gone from novelty to the default home gym purchase, and the market is now crowded with near-identical sets. BRAINGAIN is one of the few sellers here with a proper UK presence behind it: it's the company that made SmartBells, and it claims more than 100,000 customers and a 2-year UK warranty. The 40kg pair costs £369.

That warranty and the 17 weight settings are the reasons to pick it. The price and a vague spec sheet are the reasons to hesitate.

Check price on Amazonaround £369

Who it's for

It's a good fit for someone setting up a small home gym who wants a single pair to cover goblet squats, presses, rows and curls, and who values a named UK brand with a warranty over saving £100.

It's less suited to anyone chasing heavy dumbbell pressing. If you already bench 30kg dumbbells in a commercial gym, a 20kg-per-hand ceiling won't last. Our adjustable dumbbells guide lists heavier options.

What "40kg pair" means

Here's the part to get right before you order. The title says "40 kg Pair", and Amazon's recorded weight for the product is about 40kg. Two dumbbells that each reached 40kg would weigh at least 80kg together, so the numbers only make sense if each dumbbell tops out around 20kg. The bullet that says "adjust from 5kg to 40kg" is, on that reading, the pair total.

Twenty kilos per hand is still a useful ceiling. It covers dumbbell bench press, rows and goblet squats for most beginners and intermediates, and plenty of people never outgrow it for shoulder and arm work. It's not a heavy set, though, and the listing ought to say so.

The increments aren't published either. Seventeen settings across that range averages a bit over 2kg per step, which is fine, but on some twist designs the steps are uneven. If you care about small jumps for lateral raises, that detail matters.

The twist mechanism

Every twist-select dumbbell works the same way: the dumbbell sits in its cradle, you turn the handle until the number you want lines up, and when you lift, a lock holds the selected plates while the rest stay behind. BRAINGAIN calls its version a patented Twist handle. It's quick (about a second, it says) and it means you can drop the weight mid-set without hunting for collars.

The trade-off is length. Adjustable dumbbells carry all their plates' housing even at the lightest setting, so they're longer than a fixed 10kg dumbbell. On a dumbbell bench press you'll notice the ends touching at the top if you press them together, and on curls they can brush your thighs. Every set in this style shares that quirk.

Value against rivals

This is where the BRAINGAIN struggles. The HAKENO adjustable dumbbells and Mirafit adjustable dumbbells both cost noticeably less for similar weights, and BRAINGAIN's own 24kg pair sells for around £200. What the extra money buys is the brand and the 2-year warranty, and with adjustable mechanisms, a warranty is worth something: the dial and lock are the parts that fail.

Why dumbbells earn their space

Strength work two or more days a week is part of the NHS physical activity guidelines, and a single pair of adjustables can train every major muscle group. The benefits go past muscle, too: a meta-analysis of 64 controlled studies found moderate-intensity resistance training lowered systolic blood pressure by about 3mmHg on average, and by roughly 6mmHg in people with hypertension (Journal of the American Heart Association, 2016). Our full-body dumbbell workout is a good place to start.

Check the BRAINGAIN price on Amazonaround £369

Recommended reads

• The best adjustable dumbbells in the UK
• How to do a dumbbell bench press
• Full-body dumbbell workout
• HAKENO adjustable dumbbells review
• All our home gym reviews and guides