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Old 08-25-04, 10:36 PM   #1
andypdx
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New Tandem, burned breaks

Hello from the Pacific Northwest,

I found the site while googleing for information on tandem breaks. I bought my first tandem, a 2004 Cannondale RT1000, recently. I've found that coming down hills, the break calipers get so hot that the plastic parts on them melt if I don't stop frequently and put water on them. In particular, a couple of weeks ago I pedalled up Mt Constitution in the San Juan Islands (2,500 feet) with my sister (total load 400 lbs). Coming down, we stopped twice and found the plastic knobs on the calipers soft and sticky until we put water on them to cool them down.

I'd appreciate any advice. I've read http://www.rodcycle.com/articles/brakes.html which says not to use disc breaks on tandems. I chose the RT1000, because my in previous (very limited) experience, I found tandems hard to stop. I like the control and responsiveness of the breaks, but they can't seem to take the heat of more than about a 500 foot descent without overheating.
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Old 08-26-04, 04:52 PM   #2
bentbaggerlen
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What brakes are you using on the tandem? And dose your tandem have v-brake posts?
I set all my tandems up with v-brakes and a drum brake as all of the disk brakes will over heat when used to control speed on long down hills.
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Old 08-27-04, 10:07 AM   #3
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Thanks for the reply. You ask, "What brakes are you using on the tandem? And dose your tandem have v-brake posts?" I'm using the Avid mechanical disc breaks that come with the new Cannondale RT1000. I think it does have posts. Then you say "all of the disk brakes will over heat when used to control speed on long down hills." Using google, I see that you and others have said that before.

Apparently, I bought the bike without doing enough research. The salesman said that with the disc breaks, I would not need a drum. I live about 500 feet up from downtown Portland, and the first week I had the bike, one of the plastic adjusting knobs melted away as I dropped that elevation without thinking about the breaks. The Avid breaks would be ideal for Florida.

I am going to stick with the stock breaks for now. I think that in addition to costing me more money, substituting a drum and v-breaks would reduce the resale value of the bike. When I drop elevation in the future, I'll watch the breaks carefully, and after a while, I'll either sell the bike or get a drum.
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Old 08-27-04, 11:05 AM   #4
Michel Gagnon
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I don't know the specifics of the brake used, and especially the diametre of the disk, which is the most important factor.

When some people complain about disk brakes not being appropriate for tandems, it's mostly in comparison with drag brakes. Basically, with disk brakes, you should not drag the brakes all the time. You should rather let the brakes loose, gain speed, then brake hard to slow down, then release the brakes again.
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Old 08-27-04, 04:13 PM   #5
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Bummer to hear about the adjusting wheels melting. I don't think it's that you're not using the brakes right. 500 feet is not much of a descent.

If the brakes were really "overheating" they would be fading. The calipers are going to get hot, that's the nature of brakes. I think Avid made a poor material choice for the adjuster wheels. It should be pretty easy for them to switch materials and eliminate the problem. Hopefully they come out with a retrofit.

In other applications I've seen disks glowing red and still functional with no permanent damage.
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Old 08-28-04, 06:53 AM   #6
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Last weekend we went to the Bentrider Online "Bent Ride 2004" in the Finger Lakes region of NY. It rained Friday and Saturday morning. Even though it was raining Saturday morning we took the bike into town for the expo. One downhill section was about three miles long. Using the drum brake to keep the bike between 20 and 25 mph, we had no problems. At the bottom of the hill you could hear the rain drops sizzle when they hit the drum brake. This was not a steep hill, just long we did not even use our lowest gear to climb it coming back. We also did not have our touring gear on the bike, that would have added another 60 to 70 pounds of weight to the bike.

Now this was in the rain so letting the bike run up speed and then grabbing a "big fistful" of brake was not really an option. 45 to 50 mph on a road I've never ridden before in the rain... Do you have any idea how hard it is to find a stoker that will ride a bike for days or weeks on end, drink warm water that tastes like plastic, eat cold crappy food, sleep in a wet tent and still wake up the next morning and do it again? With a smile on her face?

Disk brakes I myself have damaged or have seen first hand damaged by overheating when used on tandems
Formula disk brake used by Santana- warped rotor and failed brake pad.
Avids mecs with 160mm rotors as well as 203mm rotors-melted adjusters and failed bond between brake pad backing and brake pad.
Hayes mecs and hydro with 203mm rotors- warped rotors, boiled oil and pads.
Sachs disk used on the Cannondale Moto 120 fork (Ok, this brake sucked for use on a single) Everything.

I’m not saying that disk brakes don’t work, they do. Quite well when used within there limits. I would use disk brakes on a sport tandem used for day rides and club rides and off road. But a tandem for touring, or loaded touring I’m mounting a drum.

As for changing over your brakes, don’t. You cant mount a drum on your rear hub, so you would have to build a new wheel as well. Ride with the Avids, just keep in mind their limits.
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