Razor ScreamMachine Owner's And Safety Manual page 15

If there is too much slack, the lever will go all the way to the handlebar
without the brake being applied. If there is not enough slack, the brake
will drag even when the lever is not pulled. Ideally, you want 2-3mm of
play in the lever before the brake engages (as shown in figure 8b).
To adjust, loosen the lock ring and turn the barrel 1/4 to 1/2 turn to
loose or tighten as required and squeeze the brakes to test. Continue to
adjust until the proper cable slack is attained.
If the proper amount of play cannot be achieved by adjusting the brake
lever, the excess slack must be taken up at the brake by loosening the
pinch bolt as shown in Figure 8c and pulling up the excess cable slack.
Figure 8a.
Figure 8b.
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