Instead of having 2 discrete set of 3 gears (such as a front double with rear triple setup) for a total of 6 gears, the 6 speed Brompton has a wide ratio 3 speed internal hub, which gives large jumps in gear ratios when shifting the rear hub. The left side shifter (that controls the 2 speed derailleur) then compensates to give a higher or lower overall gear ratio.
The gear ratios of all stock Brompton setups. I have a 6 speed -12% setup on my Brompton.
Since there is no gear indicator on the shifters, I decided to create my own by sticking labels onto the shifters. What is required is just a label printer and a set of white-on-black labels.
Rear 3 speed shifter, labelled 1,2,3 with the arrow indicating the current gear position.
Front 2 speed shifter, labelled - and +, indicating the lower or higher gear range.
After testing it out, I found that an easier way to remember the gears is to think of it another way. Instead of thinking of it as 2 sets of 3 speeds (like on road bikes), a better way is to think of it as 3 speeds, with each of the 3 speeds having a low (-) or high (+) setting.
The 6 speeds would then look something like this:
Gear 1: 1-
Gear 2: 1+
Gear 3: 2-
Gear 4: 2+
Gear 5: 3-
Gear 6: 3+
By remembering the 6 gears in this way, it is much easier to understand. I first select 1 out of 3 speeds using the rear shifter. Then, I adjust it to be lighter or heavier by shifting the left shifter to - or + respectively.
With this method, I no longer get confused as to how to shift up or down.
Next, in order to improve visibility, I decided to upsize the labels on the shifters, so that the numbers and signs are larger and clearer.
Larger numbers for better visibility
- and + signs also upsized
With this, the DIY gear indication is completed! It is now easy to switch gears without getting confused.