Two and a half years ago, I wrote about Efneo Gearbox, an under-development product (actually a 3-speed front gearbox) that replaces a bike’s front derailleur, probably the most disliked part of bicycles. Now it is fully developed, thoroughly tested, and available for purchase.

With a front derailleur, switching the chain between the chainrings in the crankset is an arduous process, and there’s always some risk to drop the chain, especially if the drivetrain is not in perfect condition. Efneo’s GTRO Gearbox targets these problems and aims to make things more effortless, quicker, and smooth while switching the front gear.

Efneo GTRO Gearbox is dedicated to all non-competition bikes like touring, city, e-bike, folding, recumbent, trike. It has been heavily tested in various conditions (on-road, off-road, and laboratory tests, including winter tests). However, it has not been tested for competition MTB, downhill, or dirt applications.

Efneo 3-speed front bicycle gearbox

Advantages of Efneo GTRO Gearbox

  • Easy to start from the first gear. With Efneo you can reduce to the first gear in a standstill – like in a car – and start easily in 1st gear.
  • Immediate gear change. Much quicker and easier than with a front derailleur. Change gear when pedalling and in a standstill.
  • No chain-skewing. No chain-skewing and chain-dropping when paired with a rear derailleur.
  • Easy to install. The easiest front gearbox to install ever. No frame modifications necessary. No shifter fine-tuning necessary.
  • Reduced maintenance. No need for tiresome, tricky adjustments.

GTRO Gearbox is compatible with most bicycle frames using standard square tapered 4 flats BB’s with 68 mm or 100 mm wide BB shells, with English thread. BB shell diameter can not exceed 45,6 mm.

GTRO’s 1st gear is a neutral gear (1:1). Second and third gears are incremental. GTRO’s standard chainring is 28T.

Gear | Ratio | Teeth equivalent for 28T

  • 1st | 1:1 | 28T (physical chainring size)
  • 2st | 1:1,43 | 40T (physical chainring size)
  • 3st | 1:1,79 | 50T (physical chainring size)
Efneo Gearbox – How It Works?
Efneo Gearbox is a planetary gearbox that replaces a 3-chainring crank. One chainring rotates at three different speeds in comparison to a crank. It is equivalent to a crankset 28/40/50T. The full gear ratio (1st to 3rd gear) is 179%. 

Efneo’s GTRO Gearbox is delivered with a dedicated trigger shifter. Compatible with any rear transmission (derailleur, geared hub, single speed hub, rear motor) except fixed wheel. For an internally geared hub, please check the manufacturer’s specs for the smallest front chainring allowed.

Read more about Efneo GTRO Gearbox on their website.

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