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#1
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Unnerving braking experiences; sudden braking increase.
I experienced something a bit unnerving yesterday on a
bike I have been riding a couple years. The bike is a nifty steel sport frame. The brakes are Ultegra 49 mm reach with Kool Stop pads. On descents I was waiting a bit longer before braking at turns, using more braking force, but still using progressive force, rather than slamming them. At a later point in the brake application, the braking force suddenly increased sharply. This happened more than once. Had not seen this before, and need more experiments. Any comments on this sketchy account? -- Michael Press |
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#2
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Unnerving braking experiences; sudden braking increase.
Michael,
Just a guess, but by riding on the brakes it made the (rust pad?) Kool Stops hot. They expanded and added pressure to brake surface. Then if they got slightly cocked when they were hot, soft, and draging pads the rear pads could catch and jam the wheel. It would be logical the rears would heat, expand, and grab more since the front of the pads would get direct air cooling. But that's just a guess. Dragging bike brakes seems dangerous. Are those Salmon color rust pad Kool Stops? That may have been what happened to Jobst going down the Alps. Good experience to pass on. So for cooling the pads, the AL fins wouldnt' do much since furtherst away from hot pad surface: air scoops need to divert air on the back of the pad surfaces on the rear end, top rear half, and bottom rear half of each pad. Interesting puzzle for an air dam. I may be way off, but it sounds logical any way. Thanks Michael Press wrote: I experienced something a bit unnerving yesterday on a bike I have been riding a couple years. The bike is a nifty steel sport frame. The brakes are Ultegra 49 mm reach with Kool Stop pads. On descents I was waiting a bit longer before braking at turns, using more braking force, but still using progressive force, rather than slamming them. At a later point in the brake application, the braking force suddenly increased sharply. This happened more than once. Had not seen this before, and need more experiments. Any comments on this sketchy account? -- Michael Press |
#3
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Unnerving braking experiences; sudden braking increase.
Michael Press wrote:
I experienced something a bit unnerving yesterday on a bike I have been riding a couple years. The bike is a nifty steel sport frame. The brakes are Ultegra 49 mm reach with Kool Stop pads. On descents I was waiting a bit longer before braking at turns, using more braking force, but still using progressive force, rather than slamming them. At a later point in the brake application, the braking force suddenly increased sharply. This happened more than once. Had not seen this before, and need more experiments. Any comments on this sketchy account? Something sounds very wrong here... Perhaps you've got the pads toed out (with a wider gap at the leading edge of the pad than the trailing edge). That can cause this kind of thing (though normally it'll still be somewhat progressive in nature). Maybe it's just contamination on the rim or brake pad? A bit of water? If you go into a corner on the brakes hard with a wet rim, the braking WILL "improve" sharply when the water is removed by the first couple revolutions of the wheel (give or take). Mark Hickey Habanero Cycles http://www.habcycles.com Home of the $795 ti frame |
#4
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Unnerving braking experiences; sudden braking increase.
On Jan 24, 7:21 pm, Michael Press wrote: At a later point in the brake application, the braking force suddenly increased sharply. This happened more than once. Had not seen this before, and need more experiments. Any comments on this sketchy account? I had something similar happen when I was using different sets of wheels with rims that didn't match in the rim brake path (Nisi Mixer with triangular profile, switching to box-section tubies to race on). Brake pads worn on the Mixers contacted "boxer: rims unevenly. Going for more stopping power, more shoe area would contact the rims as the brakes were pulled tighter, so I got more squeeze plus more brake pad. One emergency slow-down to avoid a crashing rider sent me over the bars when the front brake worked all too well, all of a sudden. It hadn't been a problem (the usual multi-turn crit race) until I tried to use it real hard. (You've probably checked pad-to-rim "engagement" already, posting "JIC") --D-y |
#5
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Unnerving braking experiences; sudden braking increase.
In article
.com , "ddog" wrote: Michael Press wrote: I experienced something a bit unnerving yesterday on a bike I have been riding a couple years. The bike is a nifty steel sport frame. The brakes are Ultegra 49 mm reach with Kool Stop pads. On descents I was waiting a bit longer before braking at turns, using more braking force, but still using progressive force, rather than slamming them. At a later point in the brake application, the braking force suddenly increased sharply. This happened more than once. Had not seen this before, and need more experiments. Any comments on this sketchy account? Just a guess, but by riding on the brakes it made the (rust pad?) Kool Stops hot. They expanded and added pressure to brake surface. Then if they got slightly cocked when they were hot, soft, and draging pads the rear pads could catch and jam the wheel. It would be logical the rears would heat, expand, and grab more since the front of the pads would get direct air cooling. But that's just a guess. Dragging bike brakes seems dangerous. Are those Salmon color rust pad Kool Stops? That may have been what happened to Jobst going down the Alps. Good experience to pass on. So for cooling the pads, the AL fins wouldnt' do much since furtherst away from hot pad surface: air scoops need to divert air on the back of the pad surfaces on the rear end, top rear half, and bottom rear half of each pad. Interesting puzzle for an air dam. I may be way off, but it sounds logical any way. Do not top post. I fixed it for you. In the cases reported I spent _less_ time with the brakes on. I was not dragging the brakes as you say. -- Michael Press |
#6
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Unnerving braking experiences; sudden braking increase.
"Michael Press" wrote in message
... In article .com , "ddog" wrote: Michael Press wrote: snip Do not top post. I fixed it for you. In the cases reported I spent _less_ time with the brakes on. I was not dragging the brakes as you say. -- Michael Press I am curious about the "top post" comment. It appears that bottom posting encourages bandwidth waste and the inclusion of way too much verbiage, especially in longer threads. Since all prior occurances in the thread would likely contain the same stuff, seems redundant. I realize that some folks use readers that make this desirable, and I'm not flaming. Just curious about why this became the "way" to do it on usenet? |
#7
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Unnerving braking experiences; sudden braking increase.
On Thu, 25 Jan 2007 15:26:52 -0800, "Mamba"
wrote: I am curious about the "top post" comment. It appears that bottom posting encourages bandwidth waste and the inclusion of way too much verbiage, especially in longer threads. Since all prior occurances in the thread would likely contain the same stuff, seems redundant. Top posting practically guarantees longer messages and wasted bandwidth, since there is no incentive to trim out unnecessary stuff. In long threads, or any thread, the proper thing to do is to bottom post while removing information not needed to understand the post you're writing. -- JT **************************** Remove "remove" to reply Visit http://www.jt10000.com **************************** |
#8
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Unnerving braking experiences; sudden braking increase.
Does this help?
Mamba wrote: "Michael Press" wrote in message ... In article .com , "ddog" wrote: Michael Press wrote: snip Do not top post. I fixed it for you. In the cases reported I spent _less_ time with the brakes on. I was not dragging the brakes as you say. -- Michael Press I am curious about the "top post" comment. It appears that bottom posting encourages bandwidth waste and the inclusion of way too much verbiage, especially in longer threads. Since all prior occurances in the thread would likely contain the same stuff, seems redundant. I realize that some folks use readers that make this desirable, and I'm not flaming. Just curious about why this became the "way" to do it on usenet? |
#9
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Unnerving braking experiences; sudden braking increase.
On Thu, 25 Jan 2007 16:47:25 -0800, "Bill Sornson"
wrote: Does this help? You're such a dick. Stuff like that was funny in grade school. -- JT **************************** Remove "remove" to reply Visit http://www.jt10000.com **************************** |
#10
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Unnerving braking experiences; sudden braking increase.
I experienced something a bit unnerving yesterday on a
bike I have been riding a couple years. The bike is a nifty steel sport frame. The brakes are Ultegra 49 mm reach with Kool Stop pads. On descents I was waiting a bit longer before braking at turns, using more braking force, but still using progressive force, rather than slamming them. At a later point in the brake application, the braking force suddenly increased sharply. Check both the rim and pads for signs of unusual wear; specifically, if the rim is significantly worn, you can end up with a lip near the top and bottom. As the brake pads wear, pressure is at first applied to the very small surface area of the lip, after which it drops down into the main section... which can suddenly increase the braking forces. --Mike Jacoubowsky Chain Reaction Bicycles www.ChainReaction.com Redwood City & Los Altos, CA USA |
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