Fed Fitness FEIERDUN 5-in-1 Adjustable Weights Review: Big Home Gym Value with One Serious Barbell Flaw

I started working out at home during the pandemic, and even after gyms reopened and life returned to something close to normal, I kept it up. Skipping the commute and waiting for equipment has its perks. Fed Fitness recently sent over the FEIERDUN 5-in-1 adjustable dumbbell and barbell combo, along with a Flybird weight bench, transforming my spare space into a surprisingly capable home gym. The setup promises impressive versatility in a compact footprint, though one part of that flexibility comes with an important limitation. Even so, it covers nearly everything I need for most home strength-training workouts.

Let’s talk about the weight set first, under the FEIERDUN brand. They sent the 5-in-1 set with 90 pounds, and I assume it made my UPS man cry, but I wasn’t home to see it. The set consists of dumbbell bars, a connector to turn them into a barbell, a mix of weights to reach 90 Pounds, a bar with a base to make an adjustable kettlebell, and two handles that can be used with the weights or directly on the floor as pushup handles. Alongside all this are multiple sets of locking nuts that screw on to keep the weights in place for your configuration.

The idea here is that you can build anything you might need. The dumbbells can hold up to 45lbs each, and if you connect the two dumbbells to the barbell connector you get a 90-pound barbell. I tested the weight set in several configurations, from dumbbells to barbells to kettlebells.

The weight plates themselves are excellent. They’re well-built, have smooth edges, and stack together nicely. Likewise, the handles and bars are comfortable; the dumbbell bars have nice knurling for grip, and the barbell connector has soft padding around it. If I had to nitpick anything about the kit itself, it’s that I wish it came with some way to store the weights, like a small plastic box or display shelf with ridges to hold them, along with a storage area for the locking nuts.

Using the dumbbells is easy. The setup comes together well, the nuts hold the weights on, and they feel well-balanced. Same with the kettlebell setup, but it has the same issue that a lot of adjustable kettlebells have. It’s fine for swings, but can be unwieldy to the point of uncomfortable for snatches and presses. Still, everything that was screwed together for both types of workouts stayed together.

This nut works hard, but the laws of gravity work harder.

Unfortunately, I cannot say the same for the setup in barbell mode. Anything over about 50 pounds exposes a serious flaw in the design, and it is not a minor inconvenience. The plastic locking nuts simply are not up to the task of securing heavier weights when configured as a barbell. Once you approach the upper end of what this system advertises, the stress on those nuts becomes too much, and they begin to loosen under load. That is not a “maybe tighten it later” problem; that is a “this can fail mid-lift” problem.

A 90-pound deadlift started to feel unstable within two or three reps. The plates would shift, the bar would wobble, and I found myself stopping constantly to retighten everything. Having to interrupt a set every few reps to prevent the bar from coming apart is more than annoying; it undermines confidence in the equipment. When you are holding weight in your hands, especially in compound movements, you should not be wondering whether the collars are about to give way.

Overhead presses were worse. Because I do not use a rack at home, I had to clean the bar from the floor to chest height. Any slight rotation of the bar in my hands caused the nuts to immediately begin backing off. That means a normal, expected movement in a lift can actively contribute to the failure of the locking mechanism. If you are not paying close attention, you could easily miss the early signs of loosening until the plates start sliding. That is a genuine safety risk, not just a quirk of adjustable equipment.

To be clear, I have enough lifting experience to recognize the subtle shift in balance that signals something is wrong, so I stopped and adjusted before anything catastrophic happened. A beginner might not notice that as quickly. When equipment advertises a 90-pound barbell configuration, it should safely handle 90 pounds without constant vigilance. Right now, in heavy barbell mode, it simply does not.

FEIERDUN told me they are aware this can happen in certain configurations and plan to address it in future versions. I appreciate the acknowledgment, but as it stands, I would strongly caution anyone against using this as a true heavy barbell. Treat it first and foremost as an adjustable dumbbell system. If you push the barbell to its limits, you are accepting real mechanical limitations that could cause plates to shift or come loose mid-lift.

In addition to the FEIERDUN adjustable weight set, we got to check out the Flybird WB5 Adjustable Weight Bench. You can adjust the back portion to eight different angles for both incline and decline presses, and there’s a shin support pad for when you need to be hooked in for those odd angles. It has foot pads to help keep you stable even on carpeting or uneven surfaces, and it can support up to 800lbs.

The Flybird WB5 is a fantastic weight bench, and the legs can fold down to make it slightly easier to store. The high weight support means you can load up a bar and not stress about overdoing it, plus there’s a ton of creative workouts you can do with a stable bench, like step-ups and jumps (do these at your own risk-even if the bench is stable, these are inherently riskier movements).

If you’re looking to build a home gym, adjustable weights and a weight bench should be at the top of your list. You can do a lot with them, and overall, the Fed Fitness products nail the assignment. If you treat the FEIERDUN weights as adjustable dumbbells that can (sparingly!) become barbells, they’re great. Just watch the weight limit on the barbell portion. And a good weight bench should be the cornerstone of any home gym.

This FEIERDUN 5-in-1 adjustable weight set shines in the roles it handles best and shows clear limits where it doesn’t. As an adjustable dumbbell and kettlebell system, it’s versatile, well-constructed, and budget-friendly, making it a practical choice for home exercisers who want flexibility without dedicating an entire room to equipment. Paired with the Fed Fitness Flybird WB5 bench, which feels sturdy and confidence-inspiring, you can build a surprisingly capable home setup for a reasonable investment.

That said, the barbell configuration shouldn’t be viewed as a heavy-duty solution. When a system starts to loosen near its advertised maximum, that’s a structural limitation worth respecting. Used within its comfort zone, this kit offers strong value. Just approach the barbell mode with caution and realistic expectations.

But perhaps most importantly, neither product will destroy your wallet. Effectively, you can get yourself set up with a full home gym for around $300, and you don’t have to compete with anyone else for the equipment or walk into a strange locker room that turns out to be underpants optional.

The full 90-pound FEIERDUN 5-in-1 adjustable weight set is $179.98 on Amazon, and lower-weight tiers are well under $100. The Fed Fitness Flybird WB5 Adjustable Weight Bench is $149.99 on the Fed Fitness site, but is currently on sale for $127.49.

Source: Manufacturer-provided review sample

What I Liked: Weights are good quality; Dumbbell and kettlebell setups are easy; The weight bench is solid and easy to set up and take down

What Needs Improvement: The plastic locking nuts are not reliable for heavy barbell configurations and can loosen under load, creating a safety risk; The weight hole diameters are only 1″, so below standard Olympic size