GTRO for folding

“Well, I love the gearbox. It’s a game-changer. The shifting action is flawless and smooth.”

Brompton Owner



GTRO is compatible with these folding bike brands

And many other brands. If your bike is not on the list, please email us at wiktor(małpa) with a brand and model name. We will reply immediately. You can also chat with us.


GTRO FOR FOLDING BIKE is the same product as a standard GTRO in terms of how it looks and works.

However, some folding bikes are specific regarding how their frame (and particularly their BB shell area) is constructed, how it is folded, how the cable is routed etc.

If you choose your bike brand from a drop-down menu in our web store, you will get your GTRO customized for your frame. We will add some spacers if necessary, a reaction lever will be positioned for your bike, a cable will be trimmed to the length necessary.

If you choose STRIDA, you will also get 1. beltring, 2. belt, 3. eccentric BB. All compatible with your Strida bike and necessary to complete the installation.

If your bike brand is not on the list, don’t worry. Just choose “GTRO for folding bike” and tell us your bike’s brand name in a Comment field on a checkout site. We will assist you in the installation, if necessary (in 90%, it is not necessary, but we are always here to help, and we reply within a couple of hours at worst).


A detailed review from Strida Canada.

Read a full review from Bill Wilby.


Efneo offers two types of shifters for folding bikes.

Grip shifter

Trigger shifter


On folding bikes, cable routing is sometimes tricky. That is why if we know your bike’s brand name, we can adjust a cable for you accordingly.

After the installation, please check carefully how a cable behaves when folding and unfolding your bike. Fold it and unfold carefully and notice if there is no harmful tension on a cable.


GTRO for folding is available with two versions of a chainring size – 28T or 38T, and with a 130BCD adapter for a beltring.

28T chainring

Equivalent to a 28/40/50T triple crankset.
Recommended for large wheel folding bikes (e.g. 20 inches and more).
For small-wheel bikes, we recommend a 38T chainring for a more comfortable cadence at top speed.

Our 28T chainring is made of high-quality steel – Chromoly, of 30 Rockwell C Scale hardness. It is irreplaceable.
We grant a lifetime guarantee for this chainring. You will never need to replace it because of wear.

38T chainring

Equivalent to a 38/54/68T triple crankset.
Recommended for small-wheel bikes.

If you like numbers, you can find a fantastic tool to analyze gear ratios here:
Sheldon Brown’s calculator is probably the best tool you can find online to analyze bicycle gear ratios and find out what could work best for you!

Is it possible to mount something between 28T and 38T?
The short answer is – no.
Is it possible to mount something larger than 38T?
The short answer is – yes.

If you choose a 38T chainring as your option, you will get a GTRO with a 130BCD adapter and a 38T chainring installed on it. If you wish, you can take it off and put any larger chainring compatible with a 130BCD standard. However, as far as we know, very few people need anything larger than 38T.

130 BCD adapter for a beltring

GTRO’s adapter is compatible with any beltring in a 130BCD standard – i.e. Carbon Gates, Continental and others.


GTRO for Brompton is available with two chainrings – either 28T (equivalent to 28-40-50T crankset) or 38T (equivalent to 38-54-68T). We recommend a 38T chainring for most users, but if you prefer a softer set-up, choose 28T.

If you choose “Brompton” from a drop-down menu in our web store, you will get your GTRO ready to install on your bike, with a correct chainline adjusted on a bottom bracket, a reaction lever positioned properly and a shifting cable trimmed to the right length.


If you choose “Strida” on a drop-down menu in our web store, you will get a full package ready for the installation – with a belt, a beltring and an eccentric BB compatible with your Strida.

GTRO is compatible with all Strida models, including the older ones.