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Discussion Starter · #1 ·
Descending very long mountain rodes on a fixed gear with only a front brake, the rim gets hot enough to boil water, melt tubular glue, and I've even had tubes blow from overheating. This is with standard aluminum low profile rims, like an Open Pro or Araya 335 gram tubular. I've used Campy Record and Zipp carbon specific pads, but are there other pads that might be better suited, which may handle or dissipate heat better? Even the Record pads will melt and ball up around the edges.

Would a longer pad holder and pad, like a mountain bike pad, be better? What do tandems use? Any suggestions? Thanks.
 

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Discussion Starter · #3 ·
caliper

FatTireFred said:
Yes, that would be best, but I want to stick with caliper rim brakes, and make do with what works best for that.
 

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2 brakes

I only run a front brake, like you. But if I routinely did long descents, I'd install a rear brake, For those long drags it helps a lot to spread the load to another wheel (and another hand, for that matter). If you've really heated a rim enough to blow a tube, I'd sure as heck advise installing another brake.

Have you tried Koolstop pads? I don't know how they handle that situation, but they're great for everything else.

Tandems sometimes use 3 brakes -- 2 rims and a disc on the back.
 

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Discussion Starter · #6 ·
brake

iherald said:
descending mountains on a fixed gear? you must have like 300 cadance
Not quite, but I've hit close to 200. Much over 150 sustained is really hard on you (the chafing!), thus, the brake. It's amazing how much heat can build up with constant, but easy, braking all the way down a mountain. All that energy has to go somewhere, and right into the front rim is where most of it goes. A more "efficient" brake pad might help?
 

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Discussion Starter · #7 ·
Koolstop

JCavilia said:
I only run a front brake, like you. But if I routinely did long descents, I'd install a rear brake, For those long drags it helps a lot to spread the load to another wheel (and another hand, for that matter). If you've really heated a rim enough to blow a tube, I'd sure as heck advise installing another brake.

Have you tried Koolstop pads? I don't know how they handle that situation, but they're great for everything else.
Might have to install another brake. The heat on each should be half what the front alone sees, I suppose.

Have not tried Koolstop regular pads. Might have to.
 

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n00bsauce
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The pads don't dissipate heat, the rims do that. Deep dish rims would probably be better at dissipating heat because of more mass and larger surface area. Choose brake pads for their ability to continue to provide stopping power when the rim is hot. If some pads ball up and melt they are not good but at the same time harder compounds may not give adequate stopping power. Have to find a balance. As others have said, get a rear brake. Mountain descents on a fixed gear are no place to be concerned about your manliness.
 

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Exactly

Fixed said:
Might have to install another brake. The heat on each should be half what the front alone sees, I suppose..
And for some situations (e.g., wet or otherwise slippery surfaces, where a front-wheel skid can drop you before you know it) it's nice to have a rear brake do most of the work.
 

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n00bsauce
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Harder but shorter stabs on the brake are better than constant easy braking for heat build up but that's not always possible on a fixie. Harder pads hold up better to heat but don't provide as much stopping power. With two brakes and harder pads you should be fine. Even with two brakes the front one still does most of the braking and will get hotter. In the Kool Stop line the black or the z-chromium pads should do the trick.
 

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Mel Erickson said:
The pads don't dissipate heat, the rims do that. Deep dish rims would probably be better at dissipating heat because of more mass and larger surface area. Choose brake pads for their ability to continue to provide stopping power when the rim is hot. If some pads ball up and melt they are not good but at the same time harder compounds may not give adequate stopping power. Have to find a balance.
This sounds right to me. A longer pad, like a v-brake pad, might be subject to less heat per unit area, but the rims should be just as hot as with any other pad. Many tandem rider on CycleOregon rides like to have a rear drum brake, in addition to calipers, as a drag during long descents.

If a front brake does 70% of braking in a two-brake set-up, a rear brake would reduce the energy going into the front rim by 30%. I doubt there are any rim or pad options that approach that degree of reduction in the heat load on the front brakes. In addition, the option of switching a bit between front & rear brakes, letting either cool off a bit, probably gives an even greater reduction.

Is this your Pista?
 

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n00bsauce
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On long, steep descents I alternate front and rear brakes to give time for more cooling, whether riding a fixie or regular bike. Disc brakes would be the best on a tandem and most come with them today. Mine has V brakes which are very good but I don't ride my tandem in mountains so I can't judge.
 

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ericm979 said:
How about a freewheel?
A freewheel wouldn't help with braking in a front-brake-only situation, but rather would make it worse by providing no back-pedaling options at any speed.
 

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PdxMark said:
A freewheel wouldn't help with braking in a front-brake-only situation, but rather would make it worse by providing no back-pedaling options at any speed.
It would mean that on long descents he wouldn't have to drag the brake to keep his speed down so he could pedal. It sounds like that excessive braking is the cause of his rim overheating issues.
 

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Dave Hickey said:
Might not be a bad idea....Is Mavic still making the Open Pro CD?
yes they do unless something changed...
 

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I just use Kool Stop Eagle 2's on my Open Pro Ceramics. Works fine.

And as far as I know - Mavic is still making them. At least they were in September.
 

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eRacer
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I like Kool-Stop Pads as well.
They also make some Pad/Cartridge Combos that are supposed to dissipate heat, but never used any.
For safety, I would not routinely attempt long, steep descents on a FG without having 2 brakes. Besides safety, alternating between the brakes may reduce rim heat.

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