Ebike Oracle

Review · TST

mountain7.0/10

TST Fat Retro

By John WeeksUpdated Jul 27, 2026How we score

Spec-verified against the manufacturer listing

Our verdict

7.0
/ 10

This heavily-bought fat-tire retro claims 1500W peak, 90 N·m and dual suspension for about $600, but states neither a rated wattage nor a top speed. Those are the two numbers that decide where you may legally ride it, and without them you cannot place this bike in the three-class system at all. The 20"×4" dual-suspension retro format is a genuinely comfortable trail-lite package and the sales volume is real, so if cushion per dollar is the brief this earns the look. If documentation matters more, the RPINT Fat 20 states its rated wattage, carries UL 2271 and UL 2849, and costs around $100 less.

Best for
Gravel-and-towpath riders who value cushion over paperwork

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TST Fat Retro

At a glance

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Battery
720Wh
Range
32mi

The numbers

TST Fat Retro is a electric mountain bike that scores 7.0/10 on our editorial rubric, last verified on July 27, 2026. Amazon listed it at $600 as of September 15, 2026. Prices change often, so treat that as a snapshot. On Amazon it currently ranks #42 Best Seller in Electric City Bikes. It pairs a 720 Wh battery, good for a claimed range of up to 32 miles. It best suits gravel-and-towpath riders who value cushion over paperwork.

Pros

  • + Amazon's #1 Electric Fat Bikes best-seller at the time of adding, so a huge field population
  • + Claimed 90 N·m torque, unusually high for the price if accurate
  • + Dual suspension + 20"×4" tires: the comfort-maximal budget format
  • + Removable ~720Wh battery with LCD and smartphone app
  • + $599.99 (as of Sep 15, 5:10 AM EDT, subject to change) for dual suspension plus fat tires still undercuts most of that format

Cons

  • - Rated wattage undisclosed: only "1500W peak" is stated, which no statute recognises
  • - Top speed unstated, so its legal class cannot be determined from the listing
  • - Battery voltage unstated ("15AH" alone), so capacity is our arithmetic, not their spec
  • - No UL certification mentioned
  • - Weight and brake hardware unpublished

Who is this for?

  • Gravel-and-towpath riders who value cushion over paperwork
  • Buyers comfortable verifying the speed cap and wattage plate on arrival
  • Anyone chasing the most suspension per dollar on Amazon

The 30-second verdict

This is the demand king of Amazon's fat-tire category, #1 in Electric Fat Bikes when we added it and still #1 as of August 2026 — it has since slipped off that top spot — and the hardware list explains why: dual suspension, 20"×4" rubber, a claimed 90 N·m of torque, and app connectivity for $599.99 (as of Sep 15, 5:10 AM EDT, subject to change). Our reservation is disclosure, not hardware. The listing quotes peak wattage only (1500W) and no top speed, so you cannot place it in the three-class system from the listing alone. TST proves on its own commuter that it can publish rated figures; here it chose not to. The claimed 90 N·m of torque would out-pull bikes at twice the price if the number holds, the smartphone app is a genuine rarity at this price, and the removable pack means charging happens wherever the sockets are rather than wherever the bike sleeps.

The full review, section by section. Tap any section to read it.

The peak-wattage problem, plainly

US e-bike law regulates rated (continuous) wattage, 750W in every state but Oregon, and says nothing about peak. A "1500W peak" bike may carry a perfectly legal 750W rated motor, or it may not; without the number, a path ranger or an insurer gets to guess. That's why our spec table shows rated wattage as blank rather than repeating the marketing figure. If the class question decides path access where you live, start from our class explainer and email the seller for the rated figure before buying.

Battery, range, and an assumed voltage

The listing says "15AH" and never names the voltage. Every credible bike in this bracket runs 48V, which would make ~720Wh, a big pack for the money and the basis of the 65-mile claim. As always that claim is lowest-assist and flat ground; with 4" tires and 90 N·m of torque on tap, real mixed riding lands nearer 30-35 miles. The pack is removable, and the LCD-plus-smartphone-app combination is unusual below $600.

Ride hardware

Dual suspension plus fat tires is the plushest configuration a budget frame can offer, and on gravel, towpaths, and beaten-up streets it's the right one. Expect spring forks rather than damped units, mechanical discs, and a total weight in the mid-60s (lb), unpublished like the rest of the mechanical spec. The 7-speed drivetrain and three riding modes are standard for the class; the retro styling is the one thing on this bike you can verify from the photos.

Who should buy it, and the sibling question

If you want maximum cushion for unpaved-path riding and you're comfortable confirming the speed cap yourself on arrival, the sales volume says thousands of buyers already decided yes. If disclosure is what you care about, the clearest alternative is the RPINT Fat 20: it publishes a rated wattage (500W), carries UL 2271 and UL 2849, throws in a lock and phone pouch, and as of August 2026 costs around $100 less than this bike. That is a genuinely hard combination to argue against unless you specifically want the dual suspension. Within TST's own range the City Commuter is the model that prints its rated figures on the listing, worth a look if it is showing as available when you read this, since stock on these budget listings moves week to week.

TST Fat Retro

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Frequently asked questions

What class is the TST Fat Retro?

It cannot be determined from the listing: the seller states neither rated wattage nor top speed, and those two numbers define the three-class system. If it arrives limited to 20 mph with a legal rated plate it will ride as Class 2. Confirm on the motor's rating plate and the display settings, then check your state's rules.

Why does your spec table leave wattage blank when the title says 1500W?

1500W is the peak figure, the momentary maximum under load. Statutes regulate rated (continuous) wattage, which the seller does not disclose. We record what is stated, not what marketing implies. (For the record: Oregon is the only 1,000W state, and everywhere else caps at 750W.)

Is 65 miles of range believable?

As a best case on the lowest assist on flat ground, possibly. On a ~720Wh pack pushing 4"-wide tires with a 90 N·m motor, mixed real-world riding is realistically 30-35 miles. Strong for the money; just not 65.

TST Fat Retro or RPINT Fat 20?

The RPINT states its rated wattage (500W), carries UL 2271 and UL 2849 certification, and includes a lock and phone pouch, making it the compliance-complete pick. The TST claims more torque (90 N·m) and outsells it heavily. They used to be priced alike; as of August 2026 the RPINT is around $100 cheaper, which tilts a close call. Certification, disclosure and price against muscle and momentum: we lean RPINT for apartment dwellers and anyone on a budget, and the TST only if you specifically want its dual-suspension ride.

TST Fat Retro

Bottom line

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