For most mountain bikers, adjusting the rear derailleur themselves is an absolute nightmare. If you do dare to try it, laymen can easily spend an hour and the result is often still not satisfactory. The wrap, preload, upper and lower limit stops must be adjusted as a minimum and even if you are fully aware of the function of these four adjusting screws, a good deal of experience and sensitivity is still required until all gears engage quickly and cleanly and do not start to rattle when changing the chainring.
Too complicated for most people, so they prefer to go to a specialist in a shop they trust. But that doesn't have to be the case, according to the engineers at the American company Otto Design. They have therefore developed a smartphone app which, together with two templates, is designed to determine the perfect derailleur setting. This is not just another tuning app that provides the mechanic with a little help, but rather the concept takes on the role of chief mechanic. You only have to turn the screws yourself, but you can rely completely on the app's instructions.
How the app works
But how does it work? The app uses the smartphone's front camera to read the two templates like a code. It scans the symbols printed on the back of the templates and checks whether they match the pre-saved settings. If the app is not satisfied, it instructs the screwdriver to make clearly defined changes. This all sounds like the ideal solution! The app was originally developed for road bikes, but is now also compatible with mountain bikes.
The app is compatible with Sram and Shimano 9- to 11-speed drivetrains, but is unfortunately only available in English and in the iTunes Store available. To be able to use the app, you must first install the Stencil set for 39 dollars. An initial test will show whether the system delivers what it promises.
