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  1. #1
    Double Secret Probation R900's Avatar
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    Brake Setup Questions - long

    From another post, I just installed a new carbon fork and R600 brake on our '05 Trek T2000. Front braking is greatly improved. I've always had great bikes on my MTB's and road bikes, but tandem has always been a little iffy. Now that the front is good to go what if anything should I go in the rear?

    I'm currently running the original stock Avid Shorty 6 with an aftermarket Drum brake. The drum brake does it's job and works great, but the Avid is very soft. So I've been thinking of some options:

    Do nothing - We've ridden the bike as is for several years, and really haven't had any problems.

    See if the bridge could be modified to support the rear R600 road brake - I like this idea if the existing bridge was strong enough to support a caliper. Currently it contains a boss for a fender, but the hole does not pass thru. I don't really want to have it cut out and moved or replaced as paint would be difficult to match and cost. I've not looked closely at the spacing, so need to investigate a little more.

    Switch to a v-brake and lever adapter - Although space is tight with the rack we use, might be the simplest solution, and I already have the parts.

    Swap out the drum and canit's for a disk - I like this solution, as we could save a bit of weight, it's clean, but I've read here the disk won't give us the same performance as the drum. Although, here in Indiana the drum is nice, but only rarely needed. I might have some rack issues, and it's a more costly solution.

    Sorry to ramble on, sort of thinking out loud.

    Thanks
    Time to Ride...

  2. #2
    hors category TandemGeek's Avatar
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    Disc... unless you really need the drum.

    To be candid, aside from the rear disc, I've never found any rear rim brakes to be all that effective at doing much beyond generating a lot of rim heating for not a lot of stopping power.

  3. #3
    Double Secret Probation R900's Avatar
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    Quote Originally Posted by TandemGeek View Post
    Disc... unless you really need the drum.

    To be candid, aside from the rear disc, I've never found any rear rim brakes to be all that effective at doing much beyond generating a lot of rim heating for not a lot of stopping power.
    Thanks, I was hoping you would chime in!
    Time to Ride...

  4. #4
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    As an add on to the original post. We took delivery of our new da vinci Jo Venture with front and rear Avid bb7 disc brakes. I understand that there is a brake in period (no pun intended), but seems to me that the brakes feel mushy and take quite a bit of lever movement to engage. Is this normal for disc brakes, or do I need to get the brakes adjusted. They did rub on the rotors until I re-engaged the quick releases. I was hoping with the disc brakes I would have lever action similar to my single.

    So far the da vinci is great, getting use to the gearing, but the ride is great. Most importantly, the stoker is very happy !!! We only have 30 miles on it so far, but as the Michigan weather participates, I am sure the mileage will increase rapidly.
    Mike Frank
    Mikefranktroymi@sbcglobal.net

  5. #5
    hors category TandemGeek's Avatar
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    Quote Originally Posted by R900 View Post
    Thanks, I was hoping you would chime in!
    Don't put too much stock in this... it's just one man's opinion and, again, there is a caveat.

    While they aren't the most attractive brake installations, a set of linear-pull rim brakes with the travel agent adapter will generate more braking force than just about any other rim brake short of a Magura hydraulic rim brake while still allowing for the use of a drum brake. In fact, to get all of the power out of a linear pull brake most frames will benefit from a brake stiffener to make sure braking forces aren't wasted on spreading the rear stays for fork blades. However, when maximum brake energy is required for what ever reason, and when a drag brake is truly needed, the linear pull or some very good cantilever brakes and a rear drum can't be beat.

    However, for 'sport riding' where something with better stopping power than a rim brake is desired that can bridge the gap between the super-duty rim/drum brake set-up, a large diameter rear disc seems to be a pretty good option. However, it's not necessarily something I'd pursue lightly given the expense of the experiment and lack of guaranteed performance out of the box. As you can see in others postings, getting a rear disc to perform well often times takes some mechanical aptitude on the part of the owner (only the best mechanics will ever get it right) and the patience to tweak equipment to extract the full potential of these systems.

    In closing, many of us who have the rear discs are very pleased with them; they provide a lot of piece of mind when we occasionally head to challenging terrain and if properly adjusted yield a rear brake that actually provides tangible stopping power for average sized teams, more so that most any rear rim brake I've ever used. But then again, we're hardly at the far right end of the bell curve when it comes to team weight.

    So, finish your research and run the numbers on cost. Fine tuning your existing system may be the most cost effective and best performing set-up you could hope for. Then again, there is certainly some intangible sex-appeal to be had with a front caliper / rear disc set-up...

  6. #6
    hors category TandemGeek's Avatar
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    Quote Originally Posted by mikefranktroymi View Post
    We took delivery of our new da vinci Jo Venture with front and rear Avid bb7 disc brakes. ... the brakes feel mushy and take quite a bit of lever movement to engage. Is this normal for disc brakes, or do I need to get the brakes adjusted.
    A question and then a reference:

    Question: Did you ask your dealer or perhaps either Todd or Brian at daVinci for any recommendations? Good dealers who sell premium grade tandems and the small businesses that produce them tend to be excellent resources and new tandem owners really owe it to themselves to leverage their knowledge and experience. Not only will it often times yield the right solution early on, it also helps to build the relationships that are the hallmark of the tandem community. Frankly, most of what I know that's worth a hoot I've learned from the smarter folks who do this stuff for a living. I'll get lucky once in a while (good and bad) and make some of my own discoveries, but by and large I've learned a lot from simply developing relationships with everyone who I've done business with.

    You might want to review this thread from 2005 that addresses the use of in-line cable adjusters and my favorite mod, the booster spring: Disc Brakes & the Inline Travel Agent

  7. #7
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    Thank you for the input. I have yet to talk with my dealer. Since we have so few miles on the bike, I wanted to wait until we had a few more miles. Being a newbie to disk brakes, I wanted to just check the waters. I will certainly talk to the folks at Continental (my dealer). They are great and I am sure they will set me straight. The folks at davinci are very receptive, they have always answered my questions promptly. Thanks to all of you for all of your help. I will keep you posted on our progress.
    Mike Frank
    Mikefranktroymi@sbcglobal.net

  8. #8
    hors category TandemGeek's Avatar
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    Quote Originally Posted by mikefranktroymi View Post
    T I will keep you posted on our progress.
    Sounds good.

    Also, with regard to the break-in process, that's really something to be attentive to with discs. New disc brakes have horrible performance until the rotors get fully seasoned and the pads bed-in to conform to the rotor. Short of riding around looking for steep hills to descent to accelerate the process all I can really suggest is a bit of patience and some added caution as your stopping distances / power will be somewhat diminished for a while.

    However, what you should find is that there will be a quantum leap in stopping power as you continue to put some stopping miles on the brake system. Now, recognize that you'll also feel as though you're quickly burning through your brake pads in terms of how much they'll be wearing and how often you'll need to adjust the brake pad clearance. This is where a lot of folks loose faith in the rear discs.

    Fear not and push through the break-in process and you should be rewarded with excellent stopping power and fairly good pad life. The initial pad wear seems excessive only because what you're really doing is knocking down the lower and upper edges of the inner and outer brake pad material as they begin to conform to the slight angle with which they contact the rotor. Remember, on the Avid system, the inner pad is fixed and the outer pad is pushed against the rotor. Therefore, and as you apply more braking force, the outer pad pushes the rotor up against the inner pad. Once the slight off camber contact areas between both the inner and outer pads conforms to the rotor you'll finally have 100% of the brake pad surface working on the rotor which is where the increased performance and reduced wear come about.

    Again, the only mod I've found that I needed to make as the addition of the compression spring to help with preloading the very long brake cable. No sense in wasting lever travel taking up cable slack.

  9. #9
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    Our bike is nearly identical to yours (R900); 2004 T2000 with shaved drum, recent bontrager fork and front road caliper. With 3 mountain passes and Old Snow Basin (ski resort) Road in our back yard, its a no brainer for us. "Want to live? Use the drum." We actually removed the canti's and run drum only in back. We also run what I call "tandem compact crankset": 53/39/28, 11/23 cassette for most rides, 11-26 for climbs.

    Few tandems require our specific setup. Its nice to have lots of options to make these machines capable of specific terrain and riding needs.

  10. #10
    Senior Member zonatandem's Avatar
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    Experimentation with brakes becomes as difficult as finding correct saddle for stoker!
    Perhaps we are too old school but we rely on rim brakes only; D/A caliper front and Tektro-Mini rear. Sufficient for us; we do live in up/down hilly/mountain terrain and have never felt the need for a 3rd brake. We are a rather light duo (just under 250#) and have been riding on the roads TWOgether over 33 years and thousands of miles. This works great for us.
    As for brake pad wear, seems many discs wear out pads at an alarming rate and brake needs adjusting/fiddling more often. When folks on a 'tana tour in Hawaii/Italy needed to adjust their Winzip disc several times on a long descent . . . I sort of scratch my head!
    We've descended from 9200' elevation at 40/50 mph with rim brakes only and did just fine.
    Have had one pair of Matthauser pads on Mafac rear cantilevers last 50,000 miles (gasp!).
    However, your needs/expectations may be different than ours.
    Good luck!
    Pedal on!
    Rudy and Kay/zonatandem

  11. #11
    Double Secret Probation R900's Avatar
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    Thanks again! The rack becomes the biggest issue for a disk option, as while we often don't need it, we almost always use it for food, clothing, camera, etc... Since I have a good extra v-brake and travel agent I'm going to try that first. I think I can clear the rack 99%, and just need to find a couple brake cables in my small town. Hopefully that will do the trick.

    I do like the drum, and while I don't "need" it, I do use it. I still like the idea of a disk, but with out frame configuration, it really conflicts with the rack. I did run across this conversion as well, looks like it might have better rack clearance, but I've not seen any installed in person.

    www.woodmancomponents.com

    I guess TG is right, maybe time for a new frame (my wife would kill me).

    Thanks
    Time to Ride...

  12. #12
    Double Secret Probation R900's Avatar
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    Quote Originally Posted by born2pdl View Post
    Our bike is nearly identical to yours (R900); 2004 T2000 with shaved drum, recent bontrager fork and front road caliper. With 3 mountain passes and Old Snow Basin (ski resort) Road in our back yard, its a no brainer for us. "Want to live? Use the drum." We actually removed the canti's and run drum only in back. We also run what I call "tandem compact crankset": 53/39/28, 11/23 cassette for most rides, 11-26 for climbs.

    Few tandems require our specific setup. Its nice to have lots of options to make these machines capable of specific terrain and riding needs.
    Interesting idea, do you run the drum off your STI shifter, or use separate control?
    Time to Ride...

  13. #13
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    From my STI lever. Cable tension adjustment rides a fine line between brake drag and sufficient lever range.

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