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
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You weren't absolutely clear, but I assume you mean that they work to stop the bike when applied, but fail to open completely afterward. Since you can pry them open, the most likely culprit is friction, either in the cable, caliper & lever pivots, or where the legs of the spring meet the arms.
Start with the easiest, and oil the pivot(s) with a light oil and give that a moment to wick in. Also oil where the spring legs meet the arms on both sides , since friction there can cause them to open unevenly. If that doesn't do the trick try to draw some light oil up into the cable. You might have to field strip, clean and oil, or maybe even replace the cable depending on age and condition.
When you're done, follow any tutorial on the web for final adjustment and centering.
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”
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