Efneo releases a 3-speed internal gearbox called the GTRO

Kieran Howells
Efneo releases a 3-speed internal gearbox called the GTRO

The GTRO is a 3-speed internal planetary gearbox installed on a bottom bracket axle that replaces the front crankset and derailleur.

This is a complete replacement, as the user retains three distinct gear ratios – virtual 28/40/50t combinations. It is installed on a bottom bracket axle and is compatible with almost all frames with a 68mm or 100mm English threaded BB shell.

GTRO is a product dedicated to:

  1. E-bike owners with a rear-wheel engine who want to add gears to their e-bike.
  2. Touring/hybrid bike owners who want to replace a front derailleur with a smoothly shifting set-up.
  3. Single-speed bike owners who want to add gears while keeping their sleek rear single-speed hub in place.
  4. Folding bike owners who want to get rid of their big front chainring and make their bike look better and having more gears.
  5. Recumbent and trike owners.
  6. IGH equipped bike owners who want to add a gear ratio.

The installation is supposedly simple according to the brand, and the crankset comes out of the box fully assembled and totally adjusted with an Efneo branded Microshift shifter. The bottom bracket has a specific 30.5mm axle length and 46mm right cup size with a quality-threaded bit made by Tange. Efneo offers it for 68mm and 100mm shells, and will soon offer a 73mm to fit touring mountain bikes, such as the Surly Ogre.


The 28t ratio is for starting and climbing, 40t ratio is appropriate for riding on flats, and 50t perfect for riding downhill or cruising. Efneo sees the GTRO excelling in some niche applications such as adapting an 8-speed town bike into an off-road without adding a derailleur, a low maintenance folding bike, or for the front drive of a cargo bike allowing the user to shift while stopped. It’s durable enough for touring, generally uses standard parts, and can be combined with nearly any rear drive – though be aware of max torque recommendations for SRAM and Shimano internal hubs.

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The Efneo company is currently seeking dealers and distributors for the UK. For more information or to get in touch, visit the brand’s website here

Tags: new products , cycling industry news

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