Marz wrote:
> treynolds@[EMAIL PROTECTED]
wrote:
> > jim beam wrote:
> > > Chris_MdR@[EMAIL PROTECTED]
wrote:
> > > > Hi,
> > > >
> > > > - After playing with the brakes for a few minutes, I noticed that
the
> > > > discs get noticeably warm, around 170F. Are there ever heating
issues
> > > > with disc brakes on longer downhill segments? Seems a stupid
question,
> > > > but they did get quite warm just by playing around on level ground
for
> > > > about ten minutes.
> > >
> > > they get warm because of the friction - that's what all brakes do.
> > > you'll have no problem with heating issues on a disk braked bike -
once
> > > set up correctly, use with complete confidence.
> > >
> >
> > Regarding the heating issue, I came across a couple on a tandem who
had
> > a hydraulic disk brake in back, instead of a drag brake. They said
> > that on long downhills the brake heating transfers heat to the fluid,
> > the fluid expands and they end up with the brake applied without any
> > lever action. They have to stop and let the fluid cool.
> >
> > A tandem drag brake and a downhill ATB are not the exact same
situation
> > but both can expect to sometimes apply the brake for 20-30 minutes on
a
> > very long downhill. Does this ever occur on an ATB?
> >
>
> I've never had heat cause the brakes to apply through heat expansion.
> What I do experience is dot4 brake fluid boiling (or the water in the
> fluid boiling) and I loose all braking power. And I have to wait until
> it cools before continuing down hill. On the same hill with v-brakes I
> had a front tire blow because the rim got too hot.
>
> My make of disk brake is not compatible with dot5 fluid, which if I
> could use it, would help.
>
> Here's a question, which action produces the most heat, keeping the
> brakes on to control speed on a steep hill or letting the bike go and
> then jamming on the brakes at the last second to kill the speed?
> Laters,
>
> Marz
>
> --
>There is a higher temp grade of DOT fluid called DOT 5.1. Despite it's
numerical designation, it IS NOT the same as DOT 5 fluid, it's a grade of
DOT 4 developed specifically for high temp braking (wonder why they didn't
call it 4.1?). Some of the motorcycle road racing teams are using it.
Speaking of brake fluid, when I worked in a motorcycle shop, this was the
second most neglected item of maintenance (changing the fluid). The most
neglected was checking tire pressure.
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