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  1. #1
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    Front Wheel Disc Brakes

    I realize that disc brakes have been discussed in the past so I will keep this brief....

    Has anyone heard the latest on fitting a disc brake to the front wheel on a tandem? I understand that there are a few manufacturers that have started this practice and I also understand that there are some significant engineering hurdles to overcome regarding the loads imposed on the head tube/steer tube/fork legs etc.

    I was just curious to know if we will be able to retrofit tandems in a few years by changing out the front fork.

    Thanks for any information,

    Rgds,

    Steffan Marley

  2. #2
    hors category TandemGeek's Avatar
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    Quote Originally Posted by S. Marley
    I was just curious to know if we will be able to retrofit tandems in a few years by changing out the front fork.
    I assume you're referring to road tandems...

    I think the answer is "it depends" and "maybe". There's still a lot of real-world development work and tweaking that needs to be done before a front disc brake equipped tandem will be ready for use by the average consumer. Moreover, disc brakes may not be appropriate for many teams and how they intend to use their tandems anymore than a drum brake is needed on all tandems. The key will be gaining enough experience to understand your needs and how the equipment will perform.

    However, even today it's a bit more involved that just the front fork. Based on current technology and to get it right entails a disc specific tandem road fork, a disc compatible front hub/off-set rim, and some fidding around with the brake caliper's adjustment or levers to get the right amount of cable purchase -- even on the purportedly STI & Ergo compatible Avid BB road version of their mechanical disc brakes. One builder is using specially modified Campy Ergo brake levers that have increased mechanical pull mated with the MTB version of the Avid brake. There is also some thought being given to using an in-line brake booster with the MTB brake to fine-tune the mechanical cable pull of the STI and Ergo levers. The DiaComp brake-only drop bar levers don't have this problem but they require that you use bar-end shifters. I think you get the idea... there are ways to make the mechanical discs work quite well but they aren't "out of the box, bolt-on" solutions just yet.

    Of course, if you've been around along enough the disc brake discussion sounds pretty much the same as it has since 1994. One builder has remained adamant that disc brakes aren't adequate for tandems and others have continued to investigate how the might. Of course, since 1994 he has revised his position a bit and now offers a hybrid, mechanically activated hydrualic rear disc brake as an option on his tandems so it's perhaps too soon to say that he will "never" find a configuration to his liking. The point is, they are not mainstream and problems still remain to be solved.

    As you note, this is a "hot topic" on the Hobbes forum. This search string will net you 1326 postings that talk about disc brakes, including a bunch of my own (and you can sense some frustration in many of them):
    http://search.bikelist.org/?SearchSt...D&Scope=tandem

    Hopefully the debate won't spill over to this list....

  3. #3
    Senior Member Lost Coyote's Avatar
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    Wow!! Thanks for the link Mark. And, thanks for the lack of sleep! Once I started reading the posts, I stay up waaay to late trying to read them all! Amazing how much influence marketing ploys, personal agendas, politics, and fuzzy science, has on what is available to the public. At the same time, it was refreshing to see some intelligence sneaking itís way into the mix.

    I now know that this subject reappears on regular basis and may be getting to be old hat to some. However, continued interest/demand from the buying public will eventually bring about a selection of breaking systems some of us will be happy with.
    Gravity kills.

  4. #4
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    We are owners of one of the (relatively) few dual disc tandems out there - a dual Avid mechanical disc equipped custom Bushnell, born in Dec 2003.

    Until I put a few thousand kilometers on it in all sorts of conditions with all sorts of team weights on it, I can't give reports that are more than first impressions at this time. I can say that the brakes stop durn good.

    Currently almost all my riding is as a very light team - 250 pounds (my son and I). I'm quite sure I could do an endo and catapult my son over my head if I chose to.

    Brake lever travel is "different" (we are using Shimano STI levers) than with traditional brakes. Much of the stopping force occurs after a great deal of lever travel (at least with the STI), however, with very little lever effort. Some might find them mushy. Modulating the brake is possible, but requires a lighter touch and a little practice as compared to traditional brakes. After a ride or two I do not notice this issue.

    Its possible this may be seen as a benefit for the hand-strength challenged. I'm not one of those, but certainly I feel I can exert more stopping force from a hand position on top of the brake hoods than I can with my road bike.

    Stopping force does not appear to be a problem but will comment on this more once my wife and I get some real time on the bike - then we'll be a 350 pound team. Vancouver has plenty of steep hills, including one straight out my front door - our house is quite literally the highest house in the city proper.

    I am already sold on disc brakes for use in the rain - one of the main reasons i wanted them was the rainy weather we get here in Vancouver does not stop us from riding (both commutting and recreational). Also the bike seems to remain cleaner - a minor but not unimportant benefit as far as I am concerned.

    Our Bushnell, like Ericksen dual disc tandems, has the front disc brake mounted on the right hand side of the fork. I plan on doing some tests in my basement, with the skewers completely loosened, to prove to myself that this mounting practice completely does away with the issues reported by others with left-hand mounting and drop out failure.

    I've not noticed any significant steering torque issues even under hard braking.

    I've not found the beefy fork contributes to a harsh ride at all - quite the contrary, this aluminum tandem is nicely responsive yet more comfortable than all of our other bikes, at least speaking as the captain. Perhaps I should have my son speak up

    A more detailed report will come once I can get my wife on board for an extended ride.

  5. #5
    hors category TandemGeek's Avatar
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    Congrats on the new Bushnell. Two little tips...

    1. Because of the tight tolerances involved, you'll need to be mindful to make brake pad adjustments more often that you would on your rim brake set-ups. Also, I believe once you get your pads bedded-in you'll be able to set your pads closer to the rotors.

    2. Check your disc rotor's attachment bolts after each ride. If you find that any are coming loose, remove them and then re-install with (more) blue Loctite. If you don't check them and they do come loose you'll hear some loud, disconcerting noises when the brakes are applied. It is quickly remedied by re-tightening the rotor bolts which, incidently, probably need a torx T25 disc brake wrench to adjust. Not all pocket tools have a torx T25 wrench so you'll want to make sure you have one or get one. The Crank Bros. Multi-17 is one of the few... well, and it's a really nifty little multi-tool; all of our bikes have one and the Alien's have been retired.


    Quote Originally Posted by mwatkins
    Brake lever travel is "different" (we are using Shimano STI levers) than with traditional brakes. Much of the stopping force occurs after a great deal of lever travel (at least with the STI), however, with very little lever effort. Some might find them mushy.
    This continues to be one of the "problems" that Avid needs to address with its brakes. They altered the ramping of their MTB brake to allow for use with the STI and Ergo levers but it wasn't enough and there still isn't enough brake pad travel. This is the same "problem" that had to be overcome before linear pull (aka, Shimano's V-Brakes) could be used with STI and Ergo levers. Hopefully, Avid will make the fix to their brake caliper vs. having something like a "Travel Agent" or other type of brake booster incorporated in the brake cable run.

    I've not noticed any significant steering torque issues even under hard braking.
    There's a shock (not really). I have no idea where Mr. Bill grabbed on to that issue. Good gravy, he's been building and selling off-road tandems with asymetrical front discs since '97, never mind that motorcycles have asymetrical front discs since the first disc brakes equipped models started showing up in the late 60's and early 70's.

    I've not found the beefy fork contributes to a harsh ride at all - quite the contrary, this aluminum tandem is nicely responsive yet more comfortable than all of our other bikes, at least speaking as the captain. Perhaps I should have my son speak up.
    You know, as much hyper as carbon forks get relative to their "feel" the only advantage that I've experienced is the reduced weight, which is significant. From a feel standpoint, our original -- albeit custom -- steel Erickson fork was just as good as the Alpha Q fork that replaced it.

  6. #6
    Senior Member zonatandem's Avatar
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    front disc

    Yes (!) there are front disc brake forks for tandems, including carbon forks. Contact ariZonatandems.com for more info on custom built disc compatible forks.
    Pedal on TWOgether!
    Rudy & Kay

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