Curt

Origin

Ampler was founded in 2014 in Tallinn by Ardo Kaurit and Rait Udumäe — engineering-led Estonians frustrated that e-bikes looked clunky and obviously electric. Their answer was a stealth aesthetic: a 250 W rear hub motor and a 336 Wh battery hidden inside the down tube, so the bike reads as a normal urban cycle from three metres away. The Curt is Ampler's performance flagship — the lightest model in the lineup at 14.1 kg, designed for riders who want assistance without admitting they have it. Every Curt is calibrated and ride-tested in Estonia before shipping, and in 2024 Ampler made the Curt one of the first USB-C-chargeable e-bikes — charge it with the same cable as a laptop.

Specifications

Frame: Aluminium Alloy 6061, double-butted, with battery integrated into the down tube
Weight: kg
Brakes: Shimano Deore M6100 hydraulic disc, 160 mm rotors
Wheels: 28" (700C) wheels, 12 mm thru-axle front, aluminium 45 mm fenders included

The verdict

+Strengths

Exceptionally light for an e-bike (14.1 kg belt / 15.1 kg geared) — easy to carry up stairs and lively to ride
Stealth design: looks like a normal bike, battery and motor are almost invisible
Smooth, natural torque-sensor assistance that amplifies pedalling rather than overpowering it
Low-maintenance Gates carbon belt option and quality finishing kit (Deore M6100 brakes, Panaracer GravelKing tyres, carbon fork)
Clean app-based control with Bluetooth, GPS tracking and fast charging (~2.5–3 h to full)

−Weaknesses

Battery is non-removable — you must bring the whole bike to a power outlet, awkward without indoor parking
No display and the assist button sits on the top tube, so changing modes means taking a hand off the bars
Modest 336 Wh capacity and 45 Nm torque give limited range and less grunt on steep climbs than mid-drive rivals
Premium price (from ~€3,690) versus other hub-motor commuters
Ships without a kickstand and (pre-2024 models) without USB-C charging; limited brick-and-mortar service network

Did you know

01The battery is fully integrated into the down tube and is NOT removable — you charge the whole bike via a frame port, a deliberate trade-off Ampler accepts in exchange for the clean lines and sub-15 kg weight.
02There is no handlebar display at all: assist level is changed by a single button on the top tube, and everything else (lock, stats, assist tuning) lives in the smartphone app over Bluetooth, with built-in GSM/GPS tracking.
03From a few metres away the Curt is almost indistinguishable from a regular analogue bike — the hub motor is compact and the battery is invisible, which is the entire point of the design.
04Offered in two drivetrains: a near-maintenance-free Gates CDX carbon belt single-speed (14.1 kg) and a Shimano Deore 11-speed chain version (15.1 kg) for hillier terrain.

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