Bicycles

Mid-mounted ebike gearbox simplifies drivetrain, smoothens shifting

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Exploded view of the 5-speed gearbox developed by Kosmos
Kosmos
The Nova7 rides with a mid-mount 5-speed gearbox, 250-W rear-hub motor and 46-mile battery
Kosmos
Kosmos promises a smooth, quiet and clean motor-assisted commute
Kosmos
The Nova7 features an integrated ebike display, but can be paired with a companion app for additional functionality and control
Kosmos
The Nova7's mid-mount 5-speed gearbox has been 3 years in development
Kosmos
The Nova7 can be optioned with accessories including a single-leg kickstand, full fenders and a rear cargo rack
Kosmos
Exploded view of the 5-speed gearbox developed by Kosmos
Kosmos
View gallery - 6 images

South Korean startup Kosmos has made its Indiegogo debut with a tech-packed ebike named the Nova7. The PAS commuter features a mid-mount internal gearbox, rear-hub motor with responsive torque sensing, and a low-maintenance belt drive.

The folks behind the Nova7 reckon they've been developing the 5-speed mid-drive gearbox since early 2021. A few prototypes later, and the final version was ready for installation in a mule ebike by September of last year. More design tweaks followed, ahead of field testing in the pre-Indiegogo prototype Nova7 a few months back.

The rider switches gear ratios using what looks like a modified Shimano shifter at the handlebar. The weather-sealed gearbox is mounted at the bottom bracket of a smooth-welded 6061 alloy frame that's been specifically designed to accommodate it. Cabling has been routed internally to maintain clean lines.

The Nova7's mid-mount 5-speed gearbox has been 3 years in development
Kosmos

Powering the commute is a 250-W AKM rear-hub motor that produces 35 Nm (25.8 lb.ft) of torque. Top assist speed hasn't been given, but we'd guess it's likely going to be 20 mph for the US and 25 km/h on its home turf of South Korea. The ebike will ship with a removable 374-Wh downtube battery make up of Samsung cells for up to 46 miles (74 km) of per-charge riding.

Kosmos has replaced the messy chain-drive setup for a Welltrans carbon belt drive for the promise of clean and quiet riding. A color display has been integrated into the stem for at-a-glance status checks, and connects to a companion mobile app supporting keyless activation, GPS positioning and over-the-air updates.

The Nova7 rolls on alloy rims wearing 700x38C Kenda Kwick Trax tires with Tannus Armour inserted between the tube and tire for up to 5 mm of puncture protection (including sidewalls). Stopping power comes courtesy of Shimano MT200 hydraulic disc brakes with 160-mm rotors.

Kosmos promises a smooth, quiet and clean motor-assisted commute
Kosmos

Rounding out the key specs are a 1,200-lumen LED headlight and braking tail-light, plus turn signaling to the rear. The ebike is reported to tip the scales at 55 lb (25 kg). Accessories such as a kickstand, fenders and rear rack can be optioned in. The startup also boasts that the frame, rims, spokes, motor, belt and gear unit can be fully recycled at the end of their operational lives.

The Nova7 is currently raising production funds on Indiegogo, where perks start at US$2,400 – representing a 50% saving on the suggested retail price. The usual crowdfunding cautions apply, but if all goes to plan with the remainder of the campaign, shipping is estimated to start from March 2025.

Source: Kosmos

View gallery - 6 images
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5 comments
Karmudjun
Thanks Paul. The developers have no word that I saw on maximum weight but they do offer a back rack for the E-bike. I have to admit, I'm considering this although I'm at the top height of their estimated rider comfort zone at 76". I'm also a bit over the 100Kg average male rider, so weight distribution is a concern even with a rear rack. Thanks for the write-up.
Laszlo
For an electrical engineer it may sound shocking, even abnormal to use mechanical gearbox for adjusting RPM/torque ratio of any vehicle with electric drive. Electronic "gearboxes" have been invented decades ago. A mechanical one can never be a match. Neither in weight, nor in regulation smoothness. Any clue?

Laszlo
I have to correct myself – had an update on the eBikes. It is OK to use mechanical gearboxes on eBikes. I apologize! (It is part of the concept to keep 100% of the “human drive chain”. Electric motors are limited to the role of a servo. They just help you pushing the pedal. BTW even in this case to control system the motors must have is rather sophisticated!)
PAV
My first thought is why is the motor a rear hub rather than part of the mid mounted tranny?
Solarbob
Does this setup, with a hub motor, finally open the door to Regen?