HKM-9131091 Fat Tire E-Bike Puts a 500W Hub and a 48V 20Ah 960Wh Pack in a Canister Frame on 20 x 4.0 Tires for the Trail

500W · 48V 20Ah 960Wh · 20 x 4.0 · 28 mph · coil shock · 7-speed · 90 lb · 265 lb load

An Inverted Fork and a Fat Down Tube That Hides the BatteryA Canister Pack and a Retro Stance

A 500W rear hub, a 48V 20Ah 960Wh pack inside a fat canister down tube, 20 x 4.0 fat tires, an inverted double-crown fork with a single coil shock at the rear and disc brakes. It is listed at 40 to 62 miles and 28 mph with a 265 lb rating, and at 90 lb it is built like a small motorcycle: no fenders, no rack, nothing on the frame that you did not ask for, and a canister tube that holds the battery where a fuel tank would sit.

The canister tube is the whole design idea, and it is a better one than it looks. Instead of a battery case bolted to a down tube, the pack sits inside a fat cylinder that runs from the head tube to the seat tube, which keeps 960Wh out of a rack bag and gives the bike the silhouette of a small motorbike. It also means the frame has one big structural tube doing three jobs at once: housing, stiffness and the thing you look at.

What it does not come with is worth saying plainly: there are no fenders and no rear rack in the box. That is a deliberate weight and style decision rather than an oversight, and it is the right call for a bike that is going straight onto a trail, but a commuter who needs to arrive clean will be buying mudguards on day one.

At a Glance

• 500W Rear Hub — Brushless hub with a throttle and pedal assist
• 960Wh Canister Pack — 48V 20Ah inside the fat down tube
• 40 to 62 Miles — Throttle at one end, pedal assist at the other
• 20 x 4.0 Tires — Fat casing for dirt, gravel and sand
• Inverted Fork — Double-crown front, coil shock at the rear
• Coil Shock — Single rear spring, visible in red
• Disc Brakes — Front and rear
• 7-Speed — Geared to pedal a flat pack home
• 90 lb Complete — 41 kg, a two-person lift
• 265 lb Rating — Rider plus whatever you strap on
• No Fenders or Rack — Delivered as a bare trail bike
• LCD Display — Speed, battery and assist level

Canister Frame and Fat Tires

The frame is aluminium with one oversized canister tube carrying the battery, and the front triangle is short because of it. Inverted double-crown forks usually appear on downhill bikes; here they sit on 20-inch wheels, which makes the front end stiff and over-built.

The battery lives inside that tube rather than in a case you can see, charged through a sealed port and locked with a key. There is no charge indicator on the outside, so the level is read from the display, which is one thing to know before you buy rather than after.

At the rear there is a single coil shock in red, running from the seat tube to the swingarm, so the bike has travel at both ends on top of four inches of air in each tire. That is a lot of suspension for a 20-inch wheel, and it is what stops a 90 lb bike feeling like a trolley on a rutted track.

• Frame: aluminium, canister down tube
• Battery: 960Wh inside the tube, key-locked
• Fork: inverted, double crown
• Rear: single coil shock on a swingarm
• Brakes: disc, front and rear
• Drivetrain: 7-speed, 20 x 4.0 knobby tires

Fitted as shipped: an LED headlight at the fork crown, a kickstand, the LCD on the bars and the battery keys. There are no fenders and no rear rack, and the tires are 20 x 4.0 with a knobby tread that grips on dirt and hums on pavement.

500W Hub and 960Wh of Pack

The motor is a 500W brushless rear hub with a throttle on the right grip and pedal assist through the display. On a 20-inch wheel it spins up fast, so it feels quicker than 500W suggests, and it is enough to keep four inches of fat tire turning on gravel and packed dirt where a smaller motor would bog down and stall. A geared hub also freewheels when you stop pedalling, so a descent with the assist off costs nothing.

The pack is the interesting part: 48V 20Ah, 960Wh, nearly double what a 500W bike usually carries. That ratio is why the range figure is high: a modest motor drawing from a large battery is the efficient combination, and it is also why the bike weighs 90 lb rather than 60. There is no external case to unclip, so the pack stays in the tube and charges through a sealed port above the motor. Charge time is six to eight hours on the supplied charger.

Range is listed at 40 to 62 miles, the low figure on the throttle and the high one on pedal assist. Cold weather, sand and a headwind all pull it down, so plan a trail day around 30 miles of real riding with the throttle open, and treat 62 as the flat-path best case with the assist turned down.

Who It Fits and How It Rides

One frame size covers riders from about 5 ft 4 in to 6 ft 3 in. The 20-inch wheels keep the standover low, but the canister tube is wide and the bars are tall, so the bike feels bigger than its wheel size the moment you push it. Shorter riders should sit on one before ordering.

On gravel and packed dirt it is stable and the suspension earns its keep; on pavement the knobby tread is loud and the steering is slow. With no fenders and no rack it is a fair-weather machine.

• Fire roads, farm tracks and packed dirt
• Campgrounds and trailheads
• Short city hops where stability beats speed
• Not for commuting in rain, stairs or long-distance touring

What's in the Box

Before the first ride: fit the front wheel and check both axles, set the fork and shock preload for your weight, check both brake levers and bed the pads in with ten firm stops from a walking start, then charge the pack fully. Get help lifting it out of the carton at 90 lb.

Color and Finish

A light metallic grey covers the frame, canister tube and swingarm, with black rims, a black inverted fork, a black cockpit and a black saddle, and the only strong colour is the red coil on the rear shock. It is a gunmetal palette that reads as industrial rather than sporty.

Touch-up paint in the matching grey is available on request. The wear points are the canister tube where a knee or a lock rubs it and the chainstay under the chain.

Battery Care and Maintenance

Charge the pack between 20 and 90 percent for daily use and take it to full about once a month so the management system can balance the cells. A 960Wh pack takes most of a night, and the charge port seal needs cleaning because the tube sits where spray collects.

Check tire pressure before every ride: 18 to 20 psi on pavement, 8 to 12 psi on dirt and sand, and use a gauge rather than a thumb on a four-inch casing. Check the shock preload and both axles after the first 50 miles, check the pads monthly, and check the rear spoke tension after the first 20 rides, since a hub motor and a loaded swingarm both work that wheel hard.

Specifications

Frequently Asked Questions

Service and Policies

Coverage that lasts beyond the box. Orders ship free with a tracking number in 2 to 5 business days. From delivery, the product is protected for 180 days against manufacturing defects and transit damage, returnable within 30 days for a full refund, and covered by a 24-month parts-and-labor warranty on manufacturing defects. Four policies, one idea: ship it free, protect it for 180 days, take it back for 30, and stand behind it for two years.

HKM-9131091 · 20 in fat tire electric bike · 500W brushless rear hub · 48V 20Ah 960Wh pack inside the canister down tube, key-locked · 40 to 62 miles listed range · 28 mph as configured · 7-speed drivetrain · disc brakes front and rear · inverted double-crown fork with a single coil shock at the rear · 20 x 4.0 knobby tires on black rims · aluminium canister frame · LCD display · throttle and pedal assist · LED headlight · kickstand · 90 lb complete · 265 lb load rating · light metallic grey with a red coil · preload adjustable coil shock · sealed controller · six to eight hour charge, 960Wh in the canister tube · no fenders or rack in the box · built for fire roads, dirt tracks and campgrounds rather than commuting in rain