Ask a Mechanic | Using OTTO’s Derailleur Tuning System

Collin asks, “My rear derailleur needs a tune up and I’ve seen OTTO’s Rear Derailleur tuning system; does it actually work? If so, would you mind explaining how?”

For many, drivetrain tuning remains something of a dark art—passed down through generations of secretive mechanics. Even if you’ve never worked on your bike before, the OTTO Rear Derailleur Tuning System makes the mysterious art of maintaining smooth shifting easy as pie. The OTTO system is compatible with all Shimano and SRAM 9 to 11 speed drivetrains.

Before you start your tune up, you’ll need to download the OTTO Tuning app to your iPhone 5 or newer, and you’ll need a work stand to hold your bike steady.

The first step is to calibrate your phone with both OTTO gauges individually. To ensure accurate calibration, make sure your camera or cover is clean, your hand is on a steady surface, and the camera is not pointed towards any bright light sources. Using the front-facing camera, hold the gauge about 9 inches away from your phone’s camera. Once aligned, OTTO will prompt you to adjust the gauge for proper calibration. Repeat the process for your other gauge.

This system has two features, one being CHECK and the other being TUNE. To check your derailleur, start by putting your bike into the smallest front chainring and then shifting your rear derailleur into the fourth gear down. Now you’ll install both gauges onto your drivetrain. To install the lower Orange gauge, rotate the rear derailleur all the way to the back of the bike. The gauge will clip onto the upper jockey pulley and you’ll feel it snap into place. Don’t force it. Once it’s installed, release the rear derailleur to its normal resting position. To install the upper Blue gauge, slide the black forks onto the rear axle between the frame and the cassette. Gently push down on the gauge to make sure it’s seated.

Now that both gauges are installed, you’ll need to adjust and rotate the upper Blue  gauge so that it’s parallel with the Orange one. This ensures that your phone’s camera will see the vision targets on both gauges.

Once installed and aligned, open the OTTO app and hold your phone like you would when making a normal phone call. Hold the phone about 4 inches off the back of your rear wheel and parallel with OTTO’s vision targets, making sure to point the camera straight at the rear axle. OTTO will make adjustments to find the right lighting and positioning and when it does, all of the vision targets will light up Green. At this point, OTTO will pop out an Index Score.

The ideal score is a 0, meaning your derailleur needs no adjustment. A negative score means that you’ll need to turn your barrel adjuster clockwise and re-check. A positive score means that the barrel adjuster must be turned counter-clockwise.

OTTO will also give Derailleur Angle and Twist scores. If the angle is a PLUS, then your upper jockey pulley is bent outward and if it’s a MINUS, then it’s bent inward. Any Twist greater than 2 degrees means you have a bent or misaligned derailleur hanger and should either fix or replace it.

Finally, if you get an unsatisfactory Check score and want Otto to help you TUNE your drivetrain, the Otto app offers in-App purchases, which will guide you through the adjustment process featuring their tuning guides.

The OTTO Derailleur Tuning System makes it incredibly simple to keeping your bike’s shifting buttery smooth. Make all of your bike tuning dreams come true at Art’s Cyclery.