The brakes on my '84 Univega Viva sport had that 'spongy' feel, even after I put on new cables when I converted aero brake levers... I looked at what the cause was, and I could actually see the DiaCompe G400 brake arm bending a bit. A set of Tektro dual-pivot brakes solved that issue...
Other causes of 'soft' or spongy brakes:
- Cable housing ends not cut square
- not using proper ferrules at housing ends
- Cheap housing that has some degree of compressing
- cheap inner cable that allows some degree of stretch
- Old, hard brake pads - you gotta squeeze harder to get braking effect.
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