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Old September 14th 19, 11:49 PM posted to rec.bicycles.tech
jOHN b.
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Posts: 2,421
Default Sirect Mount Brakes?

On Sat, 14 Sep 2019 10:24:37 -0400, Frank Krygowski
wrote:

On 9/13/2019 11:22 PM, John B. wrote:
On Fri, 13 Sep 2019 22:41:08 -0400, Joy Beeson
wrote:

On Fri, 13 Sep 2019 08:40:21 +0700, John B.
wrote:

On very steep slopes where rim heating might be a problem I use an all
on and all off braking scheme. Brake as strongly as possible to a slow
speed and than release the brakes and allow gravity to accelerate the
bike. than all on braking again, and so on. On the longest and
steepest hill on Phuket, perhaps a kilometer or more of severe down
hill the rims were not hotter than I could comfortably hold my hands
on.
https://www.jamiesphuketblog.com/201...in-phuket.html
A different hill but typical of Phuket hill roads.

That was the technique I used in Albany County. I would stop every
mile or so to feel my rims, and never found them hot.


If we want to be scientific maybe we can get Frank to calculate
friction heating of the rim during braking and heat dissipation when
coasting :-)


The heat input to the rims is easy to calculate. The heat dissipation
would be intensely difficult to calculate. That's why, years ago, Jobst
and others here talked about measuring rim temperatures by various
means. These were one possibility:
https://www.omega.com/en-us/sensors-...p/TL-C5-LABELS

You stick them on a surface, and as each temperature is reached, the dot
turns permanently black.


I once "proved" that a large engine exhaust system was cool enough the
be safe in a gassy environment using those stick on temperature
indicators.

But as I remember it they were for fairly high temperatures, probably
not what one hopes their rims are running at :-)
--
cheers,

John B.

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