Tern HSD, Supplemental Instructions

Page: 21 / 124

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Checking Belt Tension
Proper belt tension is essential for optimum operation. Lack of belt tension can lead to tooth jump or “skipping” which
is when the teeth of the belt slide over the teeth of the rear sprocket. Too much tension can damage the bearings
within the rear hub, can cause the system to drag, and can prematurely wear out your drive system.
Unless you have special tension measurement tool, the best option is to use the Gates Carbon Drive
Mobile App, available for Android and iPhone. The app measures belt tension from the natural frequency
(Hz) of the belt by converting the vibrational sound into the primary frequency of the belt.
• From the Carbon Drive App, click the Frequency Tab and then click Measure icon.
• Hold the phone next to the belt.
• Pluck the belt so that it vibrates similar to a guitar string. Rotate the crank quarter turn and
repeat the frequency measurement. Complete one full revolution of the belt.
• Take an average of these readings. Around 15 Hz variation per reading is considered acceptable.
• For your HSD, the average measurement should be 35-50 Hz.