Can a worn or faulty brake lever cause sponginess?

HellsCyclist
HellsCyclist Posts: 122
edited June 2014 in Workshop
I ask this coz I recently done up an old road bike and I have a spongy back brake. I changed the brake pads, wheels, cables (inner and outer) and also the front brake lever and rear derailer. I kept the old front derailer and rear brake lever. Front gear changing is fine, just a spongy rear brake. The front brake seems nice and solid, but it is a brand new tiagra lever. The rear brake/front gear lever is an old 105 triple. Im thinkin this might be the reason as everything else seems setup nicely.

Comments

  • ugo.santalucia
    ugo.santalucia Posts: 28,310
    The rear is always a big more spongy... there is a lot of cable outer and a bit of compression is almost inevitable. Unlikely to be the lever, unless it's filthy on the pivot
    left the forum March 2023
  • on-yer-bike
    on-yer-bike Posts: 2,974
    If its an old rear caliper spray WD40 on all the moving parts and open and close it lots with your hand without the cable attached. Sponginess can be caused by a dirty caliper not opening fully when the lever is released and causing the cable to go slack. Also wiggling the outer casing where it goes into the caliper can help it feel crisper.
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  • lapavoni10
    lapavoni10 Posts: 146
    As on-yer-bike says, check the caliper. Remove the cable, and check that you can squeeze caliper with your hand and it springs back sharply....if not, a ton a WD40 and keep working it (but not on the brake blocks)
    How old is the build? Hidden cables I assume?
    Check that the cable housing is seated correctly at the levers, and you have ferruls at ends, and the ends are cut square.
  • HellsCyclist
    HellsCyclist Posts: 122
    Will try the caliper squeeze thing. I did lube it previously but will double check for dirt etc. The cables arent hidden but the caliper and brake lever are at least 7 years old and went neglected for some of that time.
  • desweller
    desweller Posts: 5,175
    If any of the cable housing lengths are a bit short then you can get excessive housing movement when tension is applied to the cable, giving brake lever compliance.
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  • HellsCyclist
    HellsCyclist Posts: 122
    I checked the cable housing, plus I installed a new brake cable. I also managed to remove some free-play from the rear caliper itself. Caliper is nice and springy.....
    No improvement tho. Im convinced its something to do with that old lever unless theres something unusual I could be overlooking. Other than that Im stumped. The front brake uses the same housing, although less of it because its closer to its lever.
    I have heard of something called mechanical advantage. Is there anyway of adjusting that on Shimani STI levers?

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