Schwinn S.C. 7 Service Manual page 14

12. Fine adjustment to the belt tension can be done using a
13mm open-ended wrench to loosen or tighten the ten-
sioner spring on the idler arm.
13. Check belt tension using a sonic tension meter in the cen-
ter of the belt span. The belt should measure ~84 Hz.
14. If you do not have a sonic tension meter, you can use a
tensioning app to measure the frequency.
NOTE: App settings are provided for convenience. Core
does not support third-party apps.
Page 14