Gear ratios and shifting
GTRO’s 1st gear is neutral (1:1). Second and third gears are incremental. On 2nd gear chainring rotates 43% quicker than on 1st gear. On 3rd gear chainring rotates 79% quicker than on 1st gear. This way you can easily calculate real chainring size on each gear.
For any other chainring or beltring, follow the same scheme to calculate 2nd and 3rd gear size.
At this moment GTRO is positively tested for compatibility
with these great folding bike brands:
Compatibility tests include full folding and unfolding procedure with a GTRO installed. We test GTRO on other folding bikes and will add other options to our shop cart soon.
If you have another folding bike and wish to have a GTRO on it, please e-mail wiktor(małpa)efneo.com with your brand and model name.
Trikes & recumbents
GTRO was tested on trikes and recumbents of many different brands, including:
Rear transmission / hub
01 All rear casettes
02 Zehus Bike+ engine with chain sprocket
For the purpose of turning it on with backpedalling.
03 All rear hub motors
More on cadence and torque sensor compatibility in the Options document.
04 All internally geared hubs (IGH)
Like Shimano Nexus, Shimano Alfine, Sturmey Archer, NuVinci Enviolo, Rohloff. Please remember to check manufacturer’s manual what is the smallest size of a front chainring recommended for your IGH.
Not compatible with:
01 Mid-drive engines
Like Bafang, 8Fun, Shimano STEPS, Bosch, etc.
02 Coast brakes and fixie bikes
GTRO has a freewheel integrated inside. When backpedalling, the torque is transmitted at a very low value.
Maintenance and durability
GTRO passed an ISO 4210 test for bicycle cranks in SGS laboratory.
GTRO is sealed with three dynamic seals (including two v-rings) to protect it against water, dust, salt and sand.
No additional lubrication necessary after installation.
For bike builders and designers
If you plan to build a new bike and you think GTRO may be a good option for you, often a 3D CAD model may be the best first step to play with GTRO on your computer design board.
Please email wiktor(małpa)efneo.com to get a link to 3D .step files.