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Thread: Emergency brake

  1. #1
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    Emergency brake

    Some advice needed.
    Our tandem (Bill Philbrook/Rondinella, 1970's vintage, Canti brakes) has only 2 rims brakes and no disc/drum rear. Brakes recently changed to Paul cantilevers - better brakes but still only 2.
    We want to take it to the Alps this year and whilst the gearing etc ok, i am worried about the long descents and particular anxiety about brake failure and what i would do if this happened?
    I have thought about fitting a spoon brake - a sort of "get out of jail" option.
    Any thoughts on this and what you would do if you faced brake failure (partic front) and had a runaway tandem on a 10% hill that wouldn't slow down and a corner is approaching that you know you can't get around and the only option is collision and flying over the edge?
    Tony

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    Nigel nfmisso's Avatar
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    Go very slowly down hill.

    The brakes themselves are not likely to be the failure mode, you'll overheat the rims and have a blowout, and/or overheat the pads to the point of fade (and lots of stink).

    A spoon brake is not going to help with the overheating of the rim issue, and will most like result in overheating the tire as well = blowout sooner.

    If your rear hub has provision for a drum, a drum (hard to find) or disc could be mounted. The threading is 1.375 inch by 24 threads per inch, same as a freewheel, and the same hand as a freewheel. You'd have to fabricate a bracket for the disc brake caliper. DT Swiss makes an adapter to mount a disc, which several internet dealers in the UK stock.

    Discs are not meant to be used as drag brakes; to keep the working properly, use them hard, get the speed down quickly, then let off to allow it too cool.

    Your cantis should be used the same way.

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    Gear Combo Guru Chris_W's Avatar
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    An extra trick that the stoker and I use on long Alpine descents is to sit as upright as possible and catch as much wind as possible with our bodies, this tends to keep a few kph off of our speed and so means a bit less braking when we get to the corners. If you have a big flappy rain jacket, then put that on for the long descents, too, every bit of air resistance helps.

    Depending on how much braking you do (which depends on the steepness and twistiness of the road and your comfort level when riding at speeds) then if you stop for a couple of minutes every few kms to let everything cool off then you should have no problems. We've only bothered to do this on a few descents that were particularly steep, twisty, and long - on the majority of roads, even in the Alps, there are enough straight sections where you can lay off the brakes for a decent enough time to let them cool a bit, and then only use one brake at a time while allowing the other to cool.

    Make sure that you bring a full set of spare brake pads with you in case you wear some out.

    I don't think you need to be so worried about ending up totally out of control during a descent, but if that does happen, then try to go down while still on the road, and stay on it, rather than go over the edge; but hopefully you'll never be in a situation where you need to use that advice.

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    PMK
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    As you called it an emergency brake to keep from going over a cliff...

    Is it feasible to install this emergency brake as a U Brake just behind the bottom bracket. Again, as an emergency brake, not a drag brake or supplemental brake, only as a life saver.


    Truth be told, from your post,

    Any thoughts on this and what you would do if you faced brake failure (partic front) and had a runaway tandem on a 10% hill that wouldn't slow down and a corner is approaching that you know you can't get around and the only option is collision and flying over the edge?

    this is a thought I would say does not enter my mind. When conditions dictate, or fear becomes a factor, I slow down.

    PK
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    And most important, someone special that enjoys them with me (except the KTM's)

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    Do you know what your rear dropout spacing is? It might be too old for 140 mm. If you have 140, you might be able to find a used wheel with threads on the hub for an Arai drag brake. These brakes are not being made any more and appear now and again on Ebay. If it can be accomidated, it is the best alternative. There are also some early Phil Wood drum brake hubs around, but these were difficult to keep adjusted.
    If I was faced with many miles of 10%+ descents, I would probably opt not to use this bike!
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    pan y agua merlinextraligh's Avatar
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    The risk isn't losing braking capability; the risk is blowing a tire at speed.

    You'll know when the brakes are getting too hot, well before they become inoperable. You can both here and smell it, as the brakes start to off gas.

    So if they do overheat, you just have to stop and let them cool. You'd have to ignore a lot of warning signs, and possibly blow a tire off, before you lost the ability to brake.
    You could fall off a cliff and die.
    You could get lost and die.
    You could hit a tree and die.
    OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.

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    The worse your brakes the slower you have to go. If the lever is against the bar it's past time to get off and walk. If you've been under control you should be able to detect this before it's too late. You won't be able to save braking for the corners.

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    Thanks for all the advice and consideration.
    I think that the key advice i will take away is ;
    1. ride within the current brake capabilities - just don't let the situation arise where it runs away from you.
    2. take a break when you know things are heating up (= tyre blowout possibility)
    3. look for a better braking option.

    The rear spacing is 130mm - i can find a 40 spoke phil wood tandem disc hub that will fit but with no lugs for disc calliper mounting - looks like an investigation of retro-fit options suggested or better still a trip to bob jackson in leeds over the winter period and get some brazed on/re-paint.

    In the meantime, i have replaced the canti's with some from paul engineering in calif which has made a big difference to overall stopping power, so with a bit of restraint on the downhills, we will no doubt survive the trip in July to the mountains.

    Thanks once again for the tips.

    Great forum.

  9. #9
    Nigel nfmisso's Avatar
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    Quote Originally Posted by barkersoldbean View Post
    .........
    The rear spacing is 130mm - i can find a 40 spoke phil wood tandem disc hub that will fit but with no lugs for disc calliper mounting - looks like an investigation of retro-fit options suggested or better still a trip to bob jackson in leeds over the winter period and get some brazed on/re-paint.
    .......
    You should be able to stretch that to 135mm with no problem - assuming a steel frame, and then use one of these: 48H Halo SPIN DOCTOR 8/9 MTB Rear
    http://www.chainreactioncycles.com/M...le-Products-US
    http://www.halorims.com/products-det...hp?id=HUHASDR2
    the Sun Rhyno Lite or Velocity Dyad rim; Wheelsmith or DT Smith or similar spokes.

    Then all is need is to rig up a bracket for the disc brake caliper.

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    Tony, If you are going to visit the Bob Jackson folks, I would see if you can get them to cold-set your frame to 140 or better yet to 145 mm. 145 will open up all sorts of possibilities; Arai drum, or even 8-10 speeds in the future, which would be handy in the Alps. If they feel that 140 is the limit, there should be plenty of hubs threaded for the Arai drum available. If you watch ebay or call some of the US tandem sellers, such as Tandems Ltd or Tandems East, you should be able to round up a drum brake. At 145, you should be able to alternately be able to braze on the stuff you need for a disc brake, leaving the Canti for a back-up. I really think that the Arai, being a true drag brake, is the safer way to go.
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    Interesting that after all this debate, i decided to drive to the Tandem shop at Ironbridge - they deal in Co-motion tandems. The owner sorted out a disc braked Tandem (with couplers) for me to use in the Alps and will sort out my frame this winter - cold setting it to a wider rear spacing and fitting either an Arai drag brake or disc.
    All sorted as they say.
    Thanks for all the help.
    Tony

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    Tony, It sounds as though you now have the machine lined up that will enable you to enjoy your trip to the fullest! If your tandem shop can set up your own bike up with modern brakes (and possibly a not so modern Arai drum), as well as 9 or 10 speed (34 tooth?) cassette...I assume that you already have a triple crankset, you will have a bike that will serve you for many years and many mountain trips. Have fun and be safe!
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    Quote Originally Posted by Chris_W View Post
    An extra trick that the stoker and I use on long Alpine descents is to sit as upright as possible and catch as much wind as possible with our bodies, this tends to keep a few kph off of our speed and so means a bit less braking when we get to the corners. If you have a big flappy rain jacket, then put that on for the long descents, too, every bit of air resistance helps.
    Or maybe a parachute.

    paracycle001.jpg
    Last edited by storckm; 06-16-11 at 10:45 AM.

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    Senior Member KD5NRH's Avatar
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    This sounds like a great application for one of the Bionx wheels; (or any other regenerative hub - maybe even some other dynohubs if you have a big dump load) even if you don't use the assist getting up, maxing out the regeneration (and finding somewhere for the power to go when the battery is full - maybe carry a 12V hair dryer ) makes for a great drag brake.

  15. #15
    just another gosling Carbonfiberboy's Avatar
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    A stoker we ride with takes a vest or jacket for big descents and just holds it open like wings. My stoker hasn't progressed to that yet, but she does hold her arms out straight with hands cupped. Makes a huge difference. She says it's easy to do and the cupped hands are important. I air brake with my knees. Parachute is unworkable - too dangerous.

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    Quote Originally Posted by Carbonfiberboy View Post
    A stoker we ride with takes a vest or jacket for big descents and just holds it open like wings. My stoker hasn't progressed to that yet, but she does hold her arms out straight with hands cupped. Makes a huge difference. She says it's easy to do and the cupped hands are important. I air brake with my knees. Parachute is unworkable - too dangerous.
    Couldn't resist showing you all this - somewhat crazy but probably quite effective as an emergency "air" brake - until it snagged on a road sign and pull you up really sharp!

    http://www.mtnbikeriders.com/2010/11...stemparachute/

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    IMHO, outgassing can be pretty scary. We did a ride last fall with several 40-45mph downhills with stop signs at the bottom. Granted, I did let the bike run a few times, but even with pumping, feathering, and alternating between front and back, we noticed some serious fading. After the ride, I changed out the pads and all was good again. These were v-brakes. I'm assuming discs will be somewhat more effective.

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    The solution

    Finally sorted it.
    Found an ibis with s&s connectors and discs - and bought it.
    Alps here we come.
    It's much heavier than Bill Phillbrook tandem and our average speed has dropped by 1mph, but soooooo much better braking and can put both halves on the roof of our estate car.
    We will sell the other tandem (breaks my heart) and stick with the ibis.
    Thanks for all the advice.
    T

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    Quote Originally Posted by storckm View Post
    Or maybe a parachute.
    You are more right than you know. There are drogue chutes that track and field sprinters use to build strength. There are different sizes and designs to add varying amounts of resistance at the kinds of speeds that running humans attain. Perfect, IMO for keeping a tandem under control on a long downhill. They are dirt cheap too. Lets see if I can find one... ... ok... try this, I've seen them cheaper but dinners ready..

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