Join Date: Apr 2009
Location: New Rochelle, NY
Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
Mentioned: 57 Post(s)
Tagged: 1 Thread(s)
Quoted: 2060 Post(s)
Not sure I understand the question, so I'll cover both.
Brake centering in the open position, is controlled via the small spring tension adjusting screws down near the pivots. They change the return spring tension and you want to achieve balance. Loosening one side or tightening the other is equal, so don't take either to the end, but use them together for best balance. BTW- pivot bolt friction affects balance so put a drop of light oil on each pivot. so you know the friction is equal on both arms.
Brake closing is via the cable. It's self centering because once one shoe touches that arm stops and the other continues to move until both shoes are engaged. make sure the shoes are correctly positioned on the rim then pinch both arms together at the top to check that all is working. Then it's a matter of cable length. If the lever doesn't have enough throw to close the brake, the cable needs to be shortened via the adjusting barrel. If you run out of travel, than you need to pull the wire through the pinch bolt some more.
Before adjusting at the pinch bolt, return the barrel all the way down so you have the ability to tighten more later. Loosen the pinch bolt, and while squeezing both arms together t the top pull the wire through until tight, then tighten the pinch bolt slightly and see if the arms open roughly the right amount. You may also tighten the bolt a bit more and give a gentle squeeze of the lever to check if it's about right overall, then you can tighten the pinch bolt the rest of the way to lock it in place. Now if you need to tighten a bit more use the adjuster.
An ounce of diagnosis is worth a pound of cure.
“Never argue with an idiot. He will only bring you down to his level and beat you with experience.”, George Carlin
“One accurate measurement is worth a thousand expert opinions”
- Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance