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Side-pull brakes

Discussion in 'Bicycle Mechanics and Repairs' started by Tetedelacourse, 15 Oct 2007.

  1. Tetedelacourse

    Tetedelacourse New Member

    Location:
    Rosyth
    I just swapped my old wheels onto the wife's bike as they're lighter. But they're wider rims too, which means adjusting the brakes accordingly.

    The brakes are old-fashioned side-pull, single pivot, and as I'm no mechanic, I've been struggling to get the tension right without making the non-pivoting side stick to the rim.

    Any advice? All the advice I've found online (see link below eg) involves removing them from the frame completely, which to me seems a bit of overkill.

    http://www.parktool.com/repair/readhowto.asp?id=22
     
  2. rustychisel

    rustychisel Well-Known Member

    Nope, it's one of the great problems... and it's why new dual pivot brakes are much better (no drag). First check there's enough adjustment in the barrel nut to allow the calipers to move out a bit more, if not you'll have to slacken off the cable securing nut and loosen it a smidge (2~3mm travel might do it). Some, or most SP brakes have a flat behind the calipers and before the frame which will allow a slim spanner to fit in and centre the brake mech. Make sure the nut at the back is tight, but not too tight to impede the action. Failing that, grab the bugger and centre it by hand.
     
  3. domtyler

    domtyler Über Member

  4. NickM

    NickM Über Member

    Remove from bike. Chuck in skip. Replace with modern brakes, which are not a constant cause of frustration and annoyance.
     
  5. John the Monkey

    John the Monkey Frivolous Cyclist

    Location:
    Crewe
    Lol :ohmy:

    'Scuse my ignorance, but are dual pivots fairly easy to fit if you have the old single pivot levers on a bike? Any considerations regarding wheel rims etc to think about?
     
  6. Tetedelacourse

    Tetedelacourse New Member

    Location:
    Rosyth
    :ohmy: that's about the limit of my mechanical prowess.
     
  7. NickM

    NickM Über Member

    Road bike brake levers designed for caliper brakes, even old ones, all pull about the same amount of cable (~12-13mm). Old levers will probably work fine with modern calipers - the feel of the brakes may change a little, but you might prefer the changed feel anyway, so best to suck it and see before considering new levers. Of course, it is an advantage of new levers that cables can be hidden under the bar tape, whereas on old ones they can't.

    When buying calipers, brake drop needs to match your frame. Modern calipers come in "standard" drop (39-49mm) and "deep" drop (47-57mm). The latter accomodate mudguards or (sometimes) 700C wheels in frames built for 27" wheels. I have found Tektro to be very good.

    Most modern brake calipers use Allen-key nuts to mount them to the frame. An old frame may require plain nut mounting (or the frame drilling to accept Allen key nuts). More info here.
     
  8. John the Monkey

    John the Monkey Frivolous Cyclist

    Location:
    Crewe
    Great info NickM, thanks very much!
     
  9. fossyant

    fossyant Ride It Like You Stole It!

    Location:
    South Manchester
    Just use a cone spanner to re adjust the brakes - i.e. re centre - if they aren't puling evenly, then they could be over tightened !
    I.e you might have to undo them - a good set are no problem - my Shimano 600 have been working for 20 years with next to no adjustment - if you don't know how to rectify it, then some dual pivots might help
     
  10. John the Monkey

    John the Monkey Frivolous Cyclist

    Location:
    Crewe
    Fossy - the only way I could get mine to not rub was to slacken them off. I'm not sure I like that, as I have to pull a fair old bit before the brakes bite. The front caliper was particularly poor, and needed a quick adjustment every time I used the brake. The LBS had a look at it too, and couldn't do much with it - I think it's possibly just that the calipers/hardware aren't that good.

    On the upside, they say they'll fit dual pivots for me gratis if I supply them & take them along next time they service the bike :ohmy:
     
  11. fossyant

    fossyant Ride It Like You Stole It!

    Location:
    South Manchester
    Sounds like they were goosed then..... good deal from the LBS !
     
  12. jbarstow

    jbarstow New Member

    > The brakes are old-fashioned side-pull, single pivot, and as I'm no
    > mechanic, I've been struggling to get the tension right without
    > making the non-pivoting side stick to the rim.

    Perhaps the brake calipers are broken/worn/siezed/poor-quality? I happily use these types of brakes.

    Your posting makes me wonder. There should not be a "non-pivoting side". Both sides pivot on the single pivot. There is a spring attached to the pivot that pushes both sides out and ensures that for a given force both sides will pivot through the same angle.

    If, with the caliper removed from the bike, you hold the arms (where the brake pads attach) between your thumb and index finger and squeeze the calliper closed then you should see that the fixed spring ensures that both sides pivot freely and equally around the single pivot.

    Given this, if you attach the pivot to the frame or fork such that the arms are equally spaced from the rims (i.e. re-center them as fossyant says) and the pivot itself will not rotate with respect to the fork or frame then as you tension up the cable both sides of the calliper will pivot equally in towards the rim. You then should be able to achieve a small gap without rubbing (assuming the wheels are true).

    For this to work you also need to be sure that the cable itself only pulls the calliper together (i.e. does not apply unequal force to the calliper arms).
     
  13. John the Monkey

    John the Monkey Frivolous Cyclist

    Location:
    Crewe
    Quick update on this - I didn't fancy my chances of getting the various Nut -> recessed mount options done, so I had a look around for nut fitting dual pivots. At present, I know of two available;

    1) Alhonga Deep Drop
    Sold by Spa Cycles, these have a 57-75mm drop - ideal for 700 wheels in a 27" frame. £24 delivered.

    2) Shimano BR-A550 RX100
    Found these at Parker's - a more conventional 49-57mm drop, but about £30 more expensive than the Alhongas.
     
  14. One fundamental difference between old and new calipers is the now widespread adoption of the Shi**no SLR technology. On older brakes the spring in the caliper was expected to return not just the caliper but pull the cable and the lever back to its resting position. SLR used a small spring in the brake lever to return the lever to its resting position. A matching reduction in the strength of the caliper spring provided much better brake feel and required less effort at the lever.

    An SLR brakeset may not have the spring strength to return a non-SLR lever.
    A non-SLR brakeset with SLR calipers will require more effort at the lever for a given braking force.