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Integrated Shifters and Brake Cables

Discussion in 'Bicycle Mechanics and Repairs' started by John the Monkey, 22 Feb 2008.

  1. John the Monkey

    John the Monkey Frivolous Cyclist

    Location:
    Crewe
    Hi all,

    The new bike has these modern miracles fitted to it (in the Tiagra variety).

    Part of my bike checkover routine has always been to have a look at the brake cables - for the life of me, I can't see how I'd do this with these particular shifters. My normal method would be to pull the brake lever, and examine the exposed cable within - unless I'm missing something, this doesn't work for Tiagra...

    I'm sure I'm missing something obvious, so could some kind soul please point out to me what that is?
     
  2. alfablue

    alfablue New Member

    You should be able to see a few mm of the brake cable when you apply the brake, however I don't reckon there is much point, there won't be any visible lube on it (though it will be fine) and it won't be rusty. I would just judge it by performance. I suppose it could ultimately start to break, but very unlikely, most problems will happen at the business (caliper) end if it starts to fray.
     
  3. To check for what ? That the wire strands of the cable aren't about to fray away from the 'plum' on the end ?

    If you slacken-off the brake cam and pull the brake on, it'll open wide enough for you to see where the plum is attached inside the lever.

    This exploded view
    http://techdocs.shimano.com/media/t...ST/EV-ST-4500-2609A_v1_m56577569830637998.pdf
    shows what holds it - part 4, the 'cable hook' (which isn't hook shaped at all, it's a cylinder with a hole drilled though it, the cable goes through it and it holds the plum)

    If you want to examine the wire of the cable not being about to part from the plum, you'll have to loosen off the brake completely and push the cable into the lever, push it through far enough so that the plum comes out of the 'cable hook' and so you can see the cable wire itself.

    But short of faulty manufacture, I've never known the cable fray away from the plum, particularly as it's largely protected at this end from the elements by the lever and the outside casing - the other end of the cable, at the brake, is where it gets corroded, the individual wires of the cable split off, etc
     
  4. John the Monkey

    John the Monkey Frivolous Cyclist

    Location:
    Crewe
    Alfablue, my last ones (on the old bike) failed at the lever end (hence my paranoia about catching any fraying etc early). On those levers (non integrated) pulling the lever exposed a good run of easily visible cable - I can't seem to find anyway to do the same thing on the STIs...

    Andy - thanks for the explanation.

    Maybe I should stop worrying about the lever end of the cable then.
     
  5. alfablue

    alfablue New Member

    Jeez, I understand your worry then. Were they very old cables? Also, there is a possibility that if you had them loosely set, so there is a lot of lever movement, the extreme angle of the cable at the point it attached to the nipple could have fatigued it - just a theory. Anyway, Andy's advice is good if you want to check.
     
  6. fossyant

    fossyant Ride It Like You Stole It!

    Location:
    South Manchester
    Very unlikely to cause issues on a new bike - you can usually tell when the cables need replacing when pulling the lever isn't silky smooth.
     
  7. John the Monkey

    John the Monkey Frivolous Cyclist

    Location:
    Crewe
    Thanks everyone.

    Alfablue - on my old bike, I don't know how old the first cables were, as the bike was 2nd hand - the second set were on for about 3 months. My LBS (the wonderful Bike Boutique in Manchester) traced the problem to a fault in the levers that came with the bike (the barrel holding the "plum" of the cable wasn't rotating, so instead of the brake pull going straight from the plum, it went at a right angle from it over the edge of the hole in the barrel!)
     
  8. alfablue

    alfablue New Member

    Well, as I suspected, non-normal operation, but also it is a good message about vigilence over such things.
     
  9. Fab Foodie

    Fab Foodie hanging-on in quiet desperation ...


    Had this happen too...long before STI's.