Take the 2-minute tour ×
Bicycles Stack Exchange is a question and answer site for people who build and repair bicycles, people who train cycling, or commute on bicycles. It's 100% free, no registration required.

In a guide for adjusting Avid BB7 mechanical road disc brakes, it said:

Only use the barrel adjuster at the brake lever to adjust for cable slack. For lever throw, use the outboard adjustment knob. For brake pad wear adjustment, use both the inboard AND outboard knobs.

What is lever throw?

What is cable slack?


Which of these should I use to dictate how far I have to pull the levers to come to a dead stop?


For the BB7, it is recommended to have the inner (wheel-facing) pad about 2 times further from the rotor than the outer pad.

Avid BB7

share|improve this question
add comment

1 Answer

Lever throw is how much the lever moves in total.

Cable slack is how slack the cable is, ie. how much you have to pull before the brake pads start moving.

Park Tool says:

Squeeze lever to test caliper brake. Adjust lever modulation setting by moving pads inward or outward from rotor by using both pad-adjusting knobs. To maintain the 2:1 ratio, turn the fixed pad-adjusting knob twice as many clicks as the moving pad-adjusting knob. For example, if a looser modulation is desired, turn the inner pad-adjusting knob counter-clockwise 4 clicks and the outer pad adjusting knob counterclockwise only 2 clicks.

The throw will be controlled by the total gap between pads and disc. For a short throw, a small gap, pads screwed a long way in, for a longer throw pads further apart, pads screwed out.

share|improve this answer
    
Great, thank you! Avid's advice seems to be contradictory: when it comes to adjusting the outward pad, they recommend a certain ratio with the inner one (see updated question) — yet, then, for achieving a certain "lever throw", they suggest adjusting the outward pad some more, which will likely move away from the ratio. What am I to make of it if I want my brakes to be sharp, with little lever throw? –  Baumr Jun 12 '13 at 9:46
1  
You mean, so you can't modulate your braking force? –  Useless Jun 12 '13 at 10:36
    
Avid's advice does seem weird here, see my edit. The BB7s work by moving the outer pad inwards and bending the disc towards the inner pad. –  alex Jun 12 '13 at 15:37
1  
To get as little throw as possible, get the rotor aligned in the slot with the pads locked all the way down per the instructions. After that, discard the instructions. Put the bike on a stand and loosen up both pads until neither is touching. Tighten one down while spinning the wheel until it barely touches. Keep spinning the wheel and back it off slowly until it no longer touches. Repeat on the other pad. –  jimirings Jun 13 '13 at 14:41
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.