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The WalkingPad X21 is designed to solve one of the biggest problems with home fitness equipment: space. Most treadmills are large, heavy machines that permanently occupy a room, making them impractical for flats and smaller homes that suffer from a lack of storage space. The X21 aims to change that by offering a fully capable treadmill that folds down into a slim, vertically storable form — without feeling flimsy or compromised.
After using the WalkingPad X21 three times a week for the last two months, it’s clear that this minimalistic fitness machine isn’t just a walking pad with a marketing upgrade. It’s a genuinely capable running treadmill that just happens to fold neatly away–and it looks good too!
Double-Fold Design and Storage
The standout feature of the X21 is its double-fold mechanism. It folds in two places, allowing it to collapse into a compact vertical shape that can be stored behind a door, against a wall, or in the corner of a room. For UK homes like mine, where space is often limited, this is a massive advantage.
When unfolded, the X21 feels like a proper treadmill rather than a compromise. It looks clean and minimalist, with an aluminium and ABS frame and a subtle, modern design that blends into most living spaces.
One small downside of its material choices and design is that its width barely gets through a standard UK door entry width, and with the vertical bar being powder-coated, it can easily be scuffed if you’re squeezing it through such narrow doorways. Solid floors make it a little easier to balance it on its two tiny wheels and drag it along, but anyone with a plush carpet will struggle.
Stability and Running Feel
At around 37kg, the X21 is heavier than many compact treadmills, but that weight works in its favour. Once in place, it feels planted and stable, even at higher running speeds. It doesn’t wobble, shift, or feel like it’s struggling to keep up.
At 172cm tall, the running surface felt comfortably long enough for my natural stride, and the cushioning strikes a good balance between softness and responsiveness. It’s not overly bouncy, but adding a treadmill mat underneath could help reduce vibration and slightly soften the feel underfoot. Personally, I didn’t feel I needed to do that myself, though.
One thing you can feel, especially barefoot or with low-cushion shoes, is the folding hinge beneath the belt. It’s very subtle, not uncomfortable, and you quickly get used to it — but it is noticeable with less cushion in your running shoes. My Nike Revolution 5 running trainers were totally fine, and I didn’t feel any of the hinge underfoot.
Controls, Display, and Smart Features
The control beam with its rotary dial is one of the best control systems on any treadmill in this category. It’s minimal, simple, yet packed with some nice touches. You can fine-tune speed in 0.1 km/h steps or spin quickly to jump by 2-3 km/h, making transitions from walking to jogging or running very intuitive and quick to adjust.
The OLED displays show speed, time, distance, and calories, and there’s a removable stand behind the beam to rest a phone or tablet on. Even during faster running, the tablet remained stable on solid flooring. Yes, it does wobble, but whilst running, you don’t notice it moving at all.
The KS Fit companion app offers plenty of pre-built beginner and running plans, along with the ability to create custom workouts. Once past the beginner stage, the custom workout feature becomes particularly useful. From here, I was able to create a tailor-made workout that best matches my running style and fitness goals. Deeper integration with devices like an Apple Watch would be a welcome future upgrade, both in its app and on-beam OLED displays.
Performance and Noise
The 918W brushless motor feels smooth and consistent across the speed range. Walking and jogging are impressively quiet at around 60dB, while faster running introduces more footfall noise than motor noise at around 70db (before running on it).
Top speed is 12 km/h (just over 7 mph), which is more than enough for most home runners, and speed transitions are smooth rather than abrupt. Paired with your custom workout, you can start the app and have the whole program manage the speed, leaving you to focus on walking/running without the need to touch the dial. Although you can, should you wish to increase or decrease your pace along the way.
Practical Considerations
Through my time with the X21, there are a few minor usability issues. First is the wheels, which are quite small, making it harder to move over thick carpets or mats. If you don’t plan on moving the X21 too far, then this is a non-issue. Second, there’s no built-in bottle holder, which I feel is like a missed opportunity on a treadmill designed for running. I may look into 3D printing one in the near future.
Third, the power cable exits from the front of the base, nearest to the motor, which slightly limits how close the treadmill can sit to a wall when stored, without bending the power cable too much. A side-exit or picking up a right-angled cable would allow you to position the X21 a little closer to the wall when stored or in use.
I also encountered some bubble-popping noises occurring under the belt. This is caused by trapped air in the cushioning layers. I am told this is normal and will improve over time, and in just the short few weeks, I have noticed it happening less and less as the belt settles in.
Folding up the tail part of the base also gives off a loud ripping noise, which can be a little unsettling when you first hear it. This is the protective backing on the folding structure, coming away with every fold. It is mostly used during manufacturing and early use, and I am told it isn’t a functional part of the belt’s design. Like the popping sound, I am told this noise will settle down over time as more of this ‘glue’ comes away.
Safety and Downsides
Safety features of the X21 include a magnetic safety key, overload protection, automatic standby, and a child lock via the app. You can’t operate the walkingpad without the safety key inserted, so it pays to wear the belt instead of dangling it off the beam in front of you.
The main downsides are the lack of incline functionality, the premium price, no cup holder, and the slight hinge feel underfoot. None are dealbreakers, but they’re worth knowing.
I would have liked the belt to be a little wider, but I wouldn’t want to make the overall size of the X21 any wider along with it. The width could be taken from the vertical beam or the treadmill side walls, whilst maintaining its current footprint.
A USB-C charging port on the back of the beam would also be a nice addition, so runners could power their phones or tablet batteries whilst working out to media playing back on them.
My Impressions
The WalkingPad X21 successfully delivers something rare: a treadmill that genuinely fits into small homes without feeling like a compromise. It’s stable, well-built, quiet, and genuinely enjoyable to use over these past couple of months, and between myself and my wife, we will certainly continue to use it over our spin bike for our weekly fitness routines.
We couldn’t fit a full-size treadmill in our spare room/home gym, so the X21 serves us very well in that aspect. If you value space-saving design but still want a treadmill that feels like a real piece of fitness equipment, the X21 is one of the best compact options available right now.
TIMESTAMPS:
0:00 – WalkingPad X21 Overview
0:43 – Double Fold Design
1:22 – Storage & Size
1:52 – Stability & Feel
2:32 – Hinge Underfoot
2:50 – Dial & Controls
3:41 – KS Fit App
4:18 – Motor & Noise
4:45 – Top Speed
4:56 – Practical Issues
5:46 – Under Desk Tredmill
6:15 – Safety Features
6:29 – Things to be Aware of
7:01 – My Impressions
