Help with cantilever brakes/V-brakes and 27" wheels

Discussion in 'Cycling Equipment' started by Neb Zebulon, Feb 17, 2010.

  1. Neb Zebulon

    Neb Zebulon New Member

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    I've got an old Fuji Touring Series V that takes cantilever brakes. It currently has 27" wheels on it. I'm having trouble finding new cantilever brakes that will fit. The pads won't adjust low enough. In the future I'd like to put 700c wheels on it which will make the problem worse.
    I haven't tried V-brakes yet. I'm wondering if you have any suggestions which brakes will work best or if V-brakes would solve the problems. Thanks!!:p
     
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  2. oldbobcat

    oldbobcat Well-Known Member

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    While linear pull brakes (V-brakes) might solve your reach problem, they are frighteningly ineffective with road levers. The problem lies in the fact that a linear pull caliper is a second class lever, implying that the effort distance is always greater than the load distance. This is fine for generating huge amounts of force, but road levers just don't pull enough cable for this to happen.

    Last summer Specialized shipped a run of Tricross Sports that had linear pull brakes substituted for cantilevers. Even though these were of a special short-arm design, they performed miserably.

    Problem Solvers makes a pulley device that multiplies lever pull, called Travel Agents. If you cannot find the right cantilevers, I suggest talking to the mechanics at a good shop about finding linear pull calipers that fit and getting Travel Agents installed.
     
  3. alfeng

    alfeng Well-Known Member

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    You have to look at your bike's cantilever calipers, again ...

    The difference in the radius between a 27" and a 700c rim is only 4mm ... so, you may be able to adjust the pads more than you think.

    The pads on many cantilever calipers (e.g., Shimano, Tektro, etc.) are usually attached to a shaft that is connected to the caliper via a "gimble" which will allow you to adjust the position of the pad(s) -- in-and-out AND up-and-down. If this is the type of caliper you have then simply extend the arm inward by a couple of millimeters & cant it downward (you will need to have the 700c wheel in the frame).

    Some cantilever calipers (e.g., AVID Shorty) use the same type of pads that are common on V-brakes. These pads have ORBITAL adjusters which will allow for some up-and-down angling (the orbital adjusters are intended to be used to set the pad's toe-in); but, the amount may not be enough. If this is the type of calipers you have AND the situation is such that you can't angle them downward sufficiently, then you should be able to elongate the receiving slot by about 2mm with a standard size, RAT TAIL file without affecting the integrity of the caliper arms.
     
  4. Neb Zebulon

    Neb Zebulon New Member

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    Thanks for the info. I was looking at them more closely and the pads just won't swivel down. I did some measuring and discovered that part of the problem may be that the cantilever posts or bosses are closer together than on my other bike. They are about 62mm apart and on my other bike where cantis work fine the posts are about 80mm apart. I still don't know what to do about it though.
     
  5. alfeng

    alfeng Well-Known Member

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    Post two-or-three pics ...
     
  6. OldGoat

    OldGoat New Member

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  7. oldbobcat

    oldbobcat Well-Known Member

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    Roger that. If you can make them fit, using your old calipers is the best solution.
     
  8. alfeng

    alfeng Well-Known Member

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    The particular PAUL Racer calipers probably won't work on the OP's frame ...

    The braze-on version is what is referred to as a U-brake, and I have only seen them on BMX bikes (that doesn't mean that some early touring frames and/or the OP's frame doesn't use them) ...

    The U-brakes could be mounted to a cannibalized center-pull straddle from a MAFAC or Weinmann center-pull brake ...

    That begs the question for the OP (Neb Zebulon):
    Is the continued use of the braze-on mounts mandatory OR is the use of an alternative brake caliper acceptable?

    What is the "reach" from the bridge which connects the seat stays to the 'center' of the brake surface on a 27" wheel?

    Has the rear dropout already been respaced to either 130mm or 135mm OR will the original spacing be maintained if it isn't already 130mm or 135mm?
    BTW. The copy writer is either being un-/intentionally misleading or s/he just doesn't know what the once-highly-regarded MAFAC Racer caliper looks like ...

    While the upper part of the arms where the straddle cable connects to the caliper mimics that portion on a MAFAC center pull caliper, the more signficant lower portion is nothing like the lower portion of a MAFAC Racer ...

    On a MAFAC caliper, the brake pad has a rod which connects to the caliper arm(s) via a 'gimble' which is secured in slots which are perpendicular to the brake surface whereas the PAUL caliper uses pads which connect directly to the caliper arms via slots which are parallel to the brake surface.

    FWIW. I almost bought a PAUL rear derailleur a long, long time ago during a period of what can only be described as either conspicuous consumption or stupidity ... thank goodness that I didn't buy that rear derailleur!

    While CNC'd components may be better than components which are simply cast, they may-or-may-not be as durable as forged components ...

    IMO, The PAUL components are best classified as being over-priced, boutique stuff ...

    Oh, they may be particularly good for conversation while sitting around the outside of a coffee house, but at 130+ per wheel (that's a whopping $260+ per bike for those who may not have immediately grasped how expensive PAUL stuff is) ... WTF?!?

    Tektro U-brakes probably cost less then $30 per set, BTW.
     
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