KingSmith WalkingPad TRX21F Folding Treadmill – Quiet Double‑Fold Treadmill for Small Homes
Full‑size treadmills can feel overwhelming in small flats, especially if you want both walking and light running without a huge frame or constant noise. The KingSmith WalkingPad TRX21F folding treadmill (WalkingPad X21 series) uses a compact deck, double‑fold frame and brushless motor to deliver a comfortable stride and quiet performance while still offering up to around 12 km/h for home workouts.
This guide looks at how the TRX21F fits into flats and shared homes, using UK and US Amazon listings to focus on noise, speed range, folding format and day‑to‑day practicality.
See the KingSmith WalkingPad TRX21F folding treadmill on Amazon.co.uk (https://amzn.to/4wRqHtF).
See the WalkingPad X21 TRX21F folding treadmill on Amazon.com (https://amzn.to/3T9X9cb).
QuietFit Lab uses affiliate links. If you buy through the Visit Website or View on Amazon buttons on this page, we may earn a small commission at no extra cost to you. This helps support the site and keeps our reviews independent. As an Amazon Associate, QuietFit Lab earns from qualifying purchases.
QuietFit Lab Snapshot
Noise level: Quiet brushless motor, suitable for home use.
Apartment‑friendly: Yes – compact deck height and double‑fold frame help small‑space storage.
Vibration level: Low, with shock‑absorbing running board and EVA cushioning.
Small‑space fit: Good – vertical tri‑fold storage takes up about 0.16 m² of floor space when upright.
Best for: Users who want quiet walking and light running with a more “real treadmill” feel in a small home.
Not ideal for: People who only need a flat under‑desk pad or require very high‑speed running.
Overall, the TRX21F is built as a compact, quiet treadmill that bridges the gap between basic walking pads and bulky gym treadmills, giving flats and small homes a more capable belt without taking over the room.
Key features and specs
UK and US listings for the TRX21F / WalkingPad X21 show slightly different wording and numbers, so QuietFit Lab uses overlapping ranges from both sites rather than a single figure. Use these unless your specific retailer page lists slightly different specs.
Speed range around 1–12 km/h (about 1–7.5 mph), covering gentle walking through to light running.
Brushless motor rated up to about 2 HP, with input power around 1.25 HP / 110 W depending on listing.
Maximum user weight recommendation around 100–110 kg (220–242 lb), depending on region.
Running belt length around 121 cm / 47.6" and width about 46 cm / 18.1", designed for a comfortable walking and jogging stride in a compact footprint.
Deck height roughly 9.6 cm / 3.78", which helps reduce step height and minimise trip risk.
Double / tri‑fold frame system: deck folds up in two steps into a vertical configuration, saving floor space for storage.
Integrated handlebar with HD LED display showing speed, time, distance and calories, plus detachable phone/tablet holder.
Rotational dial speed control on the handlebar for quick, intuitive speed changes while walking or running.
App connectivity (KS Fit app) for logging workouts and setting child‑lock or speed limits, with Bluetooth connectivity mentioned on some US listings.
Emergency stop cable and safety key, included in the package.
Noise and “quiet factor”
Both UK and US product descriptions emphasise the TRX21F’s quiet brushless motor and shock‑absorbing running board, presenting it as suitable for home workouts without excessive mechanical noise. The low deck height, cushioned EVA board and multi‑layer belt are aimed at reducing impact sounds as well as vibration through the frame.
Real‑world noise will still depend on speed and user weight, but the focus on brushless motor design and shock absorption suggests that typical sessions at moderate speeds should stay neighbour‑friendly compared with larger, higher‑speed treadmills. As with most motorised belts, using a treadmill mat in flats or upstairs rooms remains a sensible extra damping step.
QuietFit Lab uses affiliate links. If you buy through the Visit Website or View on Amazon buttons on this page, we may earn a small commission at no extra cost to you. This helps support the site and keeps our reviews independent. As an Amazon Associate, QuietFit Lab earns from qualifying purchases
View the KingSmith WalkingPad TRX21F on Amazon.co.uk (latest price)
View the KingSmith WalkingPad TRX21F on Amazon.com (latest price)
Under‑desk and small‑space use
The TRX21F is a compact treadmill with a full handle frame, not a pure under‑desk walking pad, so it best suits small rooms where you can dedicate a patch of floor to a “real treadmill” feel. The tri‑fold vertical storage system is designed to minimise footprint when not in use, freeing up living‑room or office space between workouts.
Folded upright, the X21 series occupies around 0.16 m² of floor area with a compact height of roughly 100 cm. That means it can live against a wall or in a corner more easily than a conventional treadmill, while still rolling out for comfortable walking and jogging sessions on a 47.6" belt when you want to train.
Comfort, stability and safety
Product information highlights a 46 cm / 18.1" wide belt and cushioned running board aimed at a stable, spacious feel for both walking and running. The relatively low deck height helps reduce the feeling of stepping up onto the machine, which can make getting on and off safer and more intuitive for home users.
The integrated handlebar and rotary dial control give a simple, tactile way to manage speed without complex touchscreens, while the HD LED display and tablet holder support longer sessions with entertainment or app‑based guidance. Safety features like the emergency stop cable and child lock (via the KS Fit app) add extra reassurance for households sharing the treadmill.
Pros
Quiet brushless motor with shock‑absorbing running board, designed for home use.
Speed range up to around 12 km/h / 7.5 mph for walking and light running.
Double / tri‑fold frame with vertical storage that saves floor space in small rooms.
Wide belt and comfortable deck length compared with many basic walking pads.
Simple rotary dial control and HD LED display, plus tablet holder and app connectivity.
Cons
Not a pure under‑desk pad: full handle frame and belt height make it better for stand‑alone treadmill use.
Price point is higher than many basic walking pads, reflecting the wider belt and folding frame.
Maximum user weight (around 100–110 kg) may feel limiting for heavier runners.
Requires a suitable wall area for vertical storage; may not suit very cramped or irregular spaces.
As with most folding treadmills, belt length remains shorter than high‑end gym machines, which some tall users may notice at top speeds.
Who the KingSmith WalkingPad TRX21F is best for
The TRX21F is likely to suit:
Apartment dwellers who want a quiet, compact treadmill for regular walking and light running.
Home users who value easier vertical storage and a clean, minimal design over large console treadmills.
People who prefer simple dial‑based controls and tablet‑driven workouts rather than built‑in screens.
Users who want more belt width and comfort than basic flat walking pads but still need a small‑space footprint.
It is less likely to suit:
Heavy runners wanting long belts for fast intervals.
Users who need ultra‑low‑cost under‑desk pads.
Anyone whose space cannot accommodate vertical storage against a wall.
Where the KingSmith WalkingPad TRX21F is commonly available from
KingSmith / WalkingPad’s official online store and regional distributors.
Amazon.co.uk, under names like “WalkingPad Folding Treadmill for Heavy People with Handle & Large Area” and model TRX21F.
View the KingSmith WalkingPad TRX21F on Amazon.co.uk
Amazon.com, under names like “WalkingPad X Series Folding Treadmill, Smart Vertical Fold” with TRX21F model code.
View the KingSmith WalkingPad TRX21F on Amazon.com
Always check the product name (TRX21F / WalkingPad X21), listed belt size, maximum user weight and warranty details before buying, as WalkingPad also sells other X‑series treadmills and walking pads with different frames and performance levels.