Tangent's drive

Our third generation eccentric design creates standing waves of grease that circulate lubrication throughout the gearbox. Virtually no sliding action minimizes wear and contamination. How many bikes will your Tangent outlast?

Designed for simplicity, engineered for abuse. Tangent's patent pending drive unit is a combined motor and reduction gearbox in one housing. 4140 steel (aka Chromoly) is used for all gear elements and 6061-T6 for supportive elements. Our removable eccentric assembly makes the unit totally user serviceable- access and replace any worn bearing or seal with one tool, a flat-blade screwdriver. Our uniquely modified eccentric reducer allows increased efficiency, robustness and operating speed while decreasing size and weight over conventional planetary or cycloidal gearboxes. The wrap-around mount prevents twisting and allows us to transfer force to the bike frame through the bottom bearing, where the frame was designed to take it. Rotational force is transferred through a rubber mount- no clamping or bolting to frame tubes is required.  

Don't let the constraints of an OEM pedelec system dictate your suspension geometry. With Tangent, you can pick from any bike in your stable and ride faster, harder and farther than you have before. Tangent's drive does not interfere with the normal operation of the bicycle driveline- unlike some larger competitors, our system doesn't add any resistance to normal pedaling and the drive is easily moved between frames. Time to upgrade your frame? No problem, move the drive and put your old bicycle up for sale. Nobody wants to buy an overpriced used ebike with soggy batteries and components and now you don't have to lose your shirt to upgrade your ride. 

Finally, an ebike drive system built for the hardest riders and racing conditions. Think your Chinese or European built ebike can take the podium away? We doubt it. 

Tangent supports riders with pedal assist and throttle based kits (pedal assist kit for sale soon). Our PAS kit uses a higher internal reduction ratio to match the drive's output to our pedal cadence. Capable of 3000W peak and 1750W continuous, the PAS Ascent can keep up with your demands for speed. Power is easily limited and verified for your local authority figure or race marshall. The higher ratio PAS kits also accept a throttle input to turn your cargobike or rickshaw into the workhorse you've been waiting for. Massive torque makes short work of any hill, no matter your load and allow you ride the fast gears up any hill. 

The throttle kits use a 50% lower reduction ratio to run each gear longer, creating a trail devouring machine that moto riders have been waiting for. Throttle response is crisp and immediate giving you precise control over front end lightness. With torque from zero and 10k motor RPM available, crawl over the rough stuff and practice your trials skills until you see the straight then rip the wheelie into the corner. The average rear cassette provides enough range to climb any hill you dare and easily achieve 35mph with 3kW and 50mph with 6kW. The pedals still work too. You've never ridden such a versatile machine. Even the internal ratios are easily interchangeable, giving riders ultimate flexibility to use the drive how they want.



  • Mount below the downtube or inside the frame triangle; multiple mounting plate designs are available and new designs may be available upon request
  • One-piece billet aluminum housing with 360-degree cooling 
  • Sealed Chromoly gear train is user accessible 
  • Overtemperature protection with soft-cutoff
  • 100 mile greasing interval, zero internal maintenance
  • 6mm thick Aluminum mounting plates position the motor chain to make use of the inner sprocket position, eliminating twist and flex 
  • 68/73mm BB standard width. 83mm and 100mm compatible with simple spacer kit
  • White Industries HD freewheel crankset, 128mm or 148mm  ISIS BB and threaded cranks included
  • Rubber torque cushion and adjustable metal strap secure the drive to the downtube or seat tube- no clamping required 
  • Top shelf components pre-configured and ready for whatever you can dish out
  • Rider owned and operated; designed, manufactured and built in our shop in Seattle, WA 

Our tension wheel provides proper chain tension in a single part thanks to flexible spokes. Three mounting options for the cushion and strap should mean a clean fit in any frame. 

6mm Aluminum mounting plates provide more than enough rigidity and the front facing oil port makes the 100 mile grease interval easy-peasy.

One drive to fit them all, 68, 73, 83 and 100mm frames are now supported.

3kW in less than 3 kilos, including speed control and all mounting hardware 

Rubber motor mounts isolate the drive unit, preventing vibration and noise from transferring to the frame.

One cable connection keeps your bike clean