HED H3 tire blow off

Pook who? writes:

Sounds like an argument for disk brakes.

Interesting that you bring that up. I am unwilling to load my
bicycle with the extra weight and complexity to try it but I have
considered the heat I have observed. I cannot imagine that the
typical disc we see on bicycles today, weighing only a few 100
grams, can absorb the energy required without collapsing and
initiating brake failure. A crumpled disk is a certain endo that I
am unwilling to test, even if I were offered such a bicycle before
a descent.

The flimsy perforated disks offered today are a mere lacework of
thin steel that is easily deformable at room temperature and easily
collapsible at yellow heat, which it would achieve on descending
roads I have encountered on my rides.

In the summer:

http://tinyurl.com/pd86

When I first arrived in Colorado, I rather foolishly decided to go
to Winter Park, ski resort and take my bike up the ski lift and
cycle down. Now I considered myself to be a reasonably good MTB'er
but quickly found myself out of my depth; the trail being both
extremely steep and rocky (as in large rocks) After a semi-nasty
fall, I lost my nerve, and descended the rest of the slope v.slowly
indeed. Definitely slower than 10mph. My bike was equipped with
hydraulic disk brakes: Magura Julies. At no point did they fail,
indeed my controlled descent never required more than one finger.

That still doesn't assure me that the disc will not fail mechanically
on a hard descent. Riders have reported bright red discs at sunset and
knowing that, I am sure I would see yellow glow, judging from the
demands that I put on brakes on my road bicycle. It was not for
nothing that I devised epoxy heat insulators for my tubular tires on
descent that others told me were no problem although I could
completely melt rims glue and explode tires on them.

Subsequently I've ridden the same trail at much higher speed as I
became more competent, with no problems. Now I'll happily admit
that they look spindly, but I've never heard of disks collapsing as
you suggest, although a friend reports his XT disk brakes fade on
this run, but this is a pads issue I surmise. Has anyone heard of
the disk itself buckling (not just warping slightly), and indeed
actually seen said item?

I'm concerned that it soften and wrinkle, locking up the brake. Fade
or a little wobble is not a crash worthy problem but disc collapse is.
As I said, my rims get hot enough entering turns to generate plenty of
steam with rim brakes.

This may sound perverse, but I've knowingly tried to see if I could
get the rear disk to 'fade' but to no avail. I've tried this on
roads/trails that I believe are as steep as those to which you
refer, i.e 12% (cf. bottom part of Magnolia Rd, off Boulder
Canyon).

As I said, fade is not as serious a problem as disc collapse.

I'm not averse to your supposition, but my practical experience has
not borne this out.

A couple of side-notes:

The disks on my bike are the standard stainless steel 180mm/190g
front and 160mm/155g rear. These seem to be significantly larger
than most: Shimano XT (2003 model without separate spider) are
160mm/140g FRONT!

I weigh 70kg.

On my descent at Winter Park they did ooze fluid out the reservoir
as they heated up to such an extent. Now the reason for this I
believe is that Magura and Shimano both use mineral oil, instead of
DOT fluid. I can't imagine that would have happened if DOT fluid
had been spec'ed.

So I weigh 90kg and brake from 70kmh to essentially zero on successive
hairpins, or continuously on 20% and steeper roads. Austria and the
Dolomites are full of such roads.

I don't see the benefit of disks out in Colorado as there's no mud
to speak of, however in the UK they're the single best thing to have
happened to MTBs IMO; I'd never go back, to the massive drag of
clogged rims/brakes and the 'disappearing' act that rims and pads do
in such conditions.

The smooth and continuous brake response is worth the difference if
it is reliable.

Jobst Brandt

In article ,
wrote:

Ted Bennett writes:

The flimsy perforated disks offered today are a mere lacework of
thin steel that is easily deformable at room temperature and
easily collapsible at yellow heat, which it would achieve on
descending roads I have encountered on my rides.

I've had a play on a MTB with discs and a sharp stop on level
ground from only about 15mph made the front disc too hot to touch.
There isn't much heat capacity because the manufacturers have to
keep the weight competitive with rim brakes.

However, I once saw a pair of (heavy looking) touring tandemists
who were solely relying on Hope discs front and rear; the discs
were rather blued by heat but the tandemists were satisfied with
their performance so far. They weren't as drilled-out as the
latest MTB types, but I'm sure they'd still get cherry red on a
serious descent. Maybe that's part of the fun.

Tandemists who follow consumer trends are already adopting disks.
The best setup would be double discs, as this would reduce,
practically to zero, torque caused by a solitary disk. And of
course a double would result in a much larger heat capacity.

I have seen a Phil Wood double-disk front hub, but I can't provide a
Web reference. Cost? "If you have to ask..."

That's interesting. I haven't see a left hand threaded hub or a left
hand threaded brake disc attachment. Who sells these and what do they
cost? Of course the main thing is to get a fork built that can
withstand brake torque at the dropout, something conventional road
forks do not do safely. The tandem riders I know have a rear disk to
take up excess speed achieved on straight runs and then use rim brakes
to control speed just before and in turns.

Yes, I have to ask.

Jobst Brandt


I learned these tidbits from a framebuilding forum, where the
participants place a lot of emphasis on the hand-crafted aspects. The
brake mounts were manufactured by the frame builder. The hub was
specially made by PW. I did not see a picture of this hub, I must have
remembered other double threaded hubs for rears. At any rate, the discs
are attached by bolts.

Many good quality bikes have been made with hub brakes, it's hardly a
lost art to make suitably reinforced forks. The reaction arm is
attached further up the fork to diminish loads on the dropout.

If you want to know what Phil would charge you to make such a hub, it
would be better to ask them directly. I'd be interested in knowing, but
it would be better to have an order for 500 in hand before idly asking
the price of one.

--
Ted Bennett
Portland OR

I have now ridden the H3 wheels in a couple of TT's and a triathlon
(approx 50 miles total) without incident. The tires I am using are
Continental Supersonic 20mm on front and 23 mm on the back. Both were
fairly tight to fit especially the back which has given me more
confidence - even though previous comments have suggested this makes
no difference to the likelyhood of the tire blowing of the rim.

Tubes are butyl. The comments below regarding latex tubes are possibly
correct about using talc but one thing I considered is that excess
talc may aid the tire to slip off the rim.

Also latex tubes tend to be slightly wider (I presume so they stretch
less) than narrow butyl tubes and this does not aid fitting especially
with 20mm tires.

Thanks for all the comments! Its nice to have somewhere to discuss
these issues.

On Fri, 14 May 2004 12:15:54 -0700, gwhite
wrote:



nospam wrote:

Also I'm gonna stop using latex tubes because I feel it is easier for
'tube inclusions' to occur.

I too have noted a great deal of "inclusion difficulty" with certain combinations of tires and latex
tubes. At times I found it extremely difficult to get the latex tubes installed correctly because
they seemed to "stick" to the tire and not "want" to get seated properly inside the tire. Different
amounts of air volume was tried to help form and unform the tubes in the hope the technique would
help -- it was mostly to no avail.

The simplest and most effective way to keep the tubes from sticking in the wrong position
(specifically getting stuck under the tire bead), was to talc the combination before installation.
Then the tubes don't stick to the tire while trying to get them installed. Just note that "talcing
tubes/tires," as an issue, has a religious fervor associated with it. As best I can tell, it rarely
matters one way or the other whether one does or does not do it. That said, in this specific case,
it seemed to greatly help get the tubes seated properly. I have never noted a situation with butyl
tubes where the effect was so strongly pronounced as that with latex tubes. So another way of
"solving the problem" is to only use butyl tubes, as you noted.

I have now ridden the H3 wheels in a couple of TT's and a triathlon
(approx 50 miles total) without incident. The tires I am using are
Continental Supersonic 20mm on front and 23 mm on the back. Both were
fairly tight to fit especially the back which has given me more
confidence - even though previous comments have suggested this makes
no difference to the likelyhood of the tire blowing of the rim.

Tubes are butyl. The comments below regarding latex tubes are possibly
correct about using talc but one thing I considered is that excess
talc may aid the tire to slip off the rim.

Also latex tubes tend to be slightly wider (I presume so they stretch
less) than narrow butyl tubes and this does not aid fitting especially
with 20mm tires.

Thanks for all the comments! Its nice to have somewhere to discuss
these issues.

On Fri, 14 May 2004 12:15:54 -0700, gwhite
wrote:



nospam wrote:

Also I'm gonna stop using latex tubes because I feel it is easier for
'tube inclusions' to occur.

I too have noted a great deal of "inclusion difficulty" with certain combinations of tires and latex
tubes. At times I found it extremely difficult to get the latex tubes installed correctly because
they seemed to "stick" to the tire and not "want" to get seated properly inside the tire. Different
amounts of air volume was tried to help form and unform the tubes in the hope the technique would
help -- it was mostly to no avail.

The simplest and most effective way to keep the tubes from sticking in the wrong position
(specifically getting stuck under the tire bead), was to talc the combination before installation.
Then the tubes don't stick to the tire while trying to get them installed. Just note that "talcing
tubes/tires," as an issue, has a religious fervor associated with it. As best I can tell, it rarely
matters one way or the other whether one does or does not do it. That said, in this specific case,
it seemed to greatly help get the tubes seated properly. I have never noted a situation with butyl
tubes where the effect was so strongly pronounced as that with latex tubes. So another way of
"solving the problem" is to only use butyl tubes, as you noted.

I've used Michelin Latex tubes and the 20c Conti Supersonics on my H3 front
for a season and have never had a problem. Last night I put a new veloflex
on
and pumped it up-- at 80 psi, Ka-blam!! On the second go, I pumped up to
about 20psi and then went all the way around on both sides, pushing the bead
in
to make sure nothing was peeking under. Worked fine.

I have had far fewer flats with latex tubes and, at least according to some
fairly
old studies, they have lower rolling resistance. Might be worth the extra
trouble
to put on (and pump up before each race).

-jens



"nospam yahoo.com" oatsandpolos@ wrote in message
...
I have now ridden the H3 wheels in a couple of TT's and a triathlon
(approx 50 miles total) without incident. The tires I am using are
Continental Supersonic 20mm on front and 23 mm on the back. Both were
fairly tight to fit especially the back which has given me more
confidence - even though previous comments have suggested this makes
no difference to the likelyhood of the tire blowing of the rim.

Tubes are butyl. The comments below regarding latex tubes are possibly
correct about using talc but one thing I considered is that excess
talc may aid the tire to slip off the rim.

Also latex tubes tend to be slightly wider (I presume so they stretch
less) than narrow butyl tubes and this does not aid fitting especially
with 20mm tires.

Thanks for all the comments! Its nice to have somewhere to discuss
these issues.

On Fri, 14 May 2004 12:15:54 -0700, gwhite
wrote:



nospam wrote:

Also I'm gonna stop using latex tubes because I feel it is easier for
'tube inclusions' to occur.

I too have noted a great deal of "inclusion difficulty" with certain
combinations of tires and latex
tubes. At times I found it extremely difficult to get the latex tubes
installed correctly because
they seemed to "stick" to the tire and not "want" to get seated properly
inside the tire. Different
amounts of air volume was tried to help form and unform the tubes in the
hope the technique would
help -- it was mostly to no avail.

The simplest and most effective way to keep the tubes from sticking in
the wrong position
(specifically getting stuck under the tire bead), was to talc the
combination before installation.
Then the tubes don't stick to the tire while trying to get them
installed. Just note that "talcing
tubes/tires," as an issue, has a religious fervor associated with it. As
best I can tell, it rarely
matters one way or the other whether one does or does not do it. That
said, in this specific case,
it seemed to greatly help get the tubes seated properly. I have never
noted a situation with butyl
tubes where the effect was so strongly pronounced as that with latex
tubes. So another way of
"solving the problem" is to only use butyl tubes, as you noted.

I've used Michelin Latex tubes and the 20c Conti Supersonics on my H3 front
for a season and have never had a problem. Last night I put a new veloflex
on
and pumped it up-- at 80 psi, Ka-blam!! On the second go, I pumped up to
about 20psi and then went all the way around on both sides, pushing the bead
in
to make sure nothing was peeking under. Worked fine.

I have had far fewer flats with latex tubes and, at least according to some
fairly
old studies, they have lower rolling resistance. Might be worth the extra
trouble
to put on (and pump up before each race).

-jens



"nospam yahoo.com" oatsandpolos@ wrote in message
...
I have now ridden the H3 wheels in a couple of TT's and a triathlon
(approx 50 miles total) without incident. The tires I am using are
Continental Supersonic 20mm on front and 23 mm on the back. Both were
fairly tight to fit especially the back which has given me more
confidence - even though previous comments have suggested this makes
no difference to the likelyhood of the tire blowing of the rim.

Tubes are butyl. The comments below regarding latex tubes are possibly
correct about using talc but one thing I considered is that excess
talc may aid the tire to slip off the rim.

Also latex tubes tend to be slightly wider (I presume so they stretch
less) than narrow butyl tubes and this does not aid fitting especially
with 20mm tires.

Thanks for all the comments! Its nice to have somewhere to discuss
these issues.

On Fri, 14 May 2004 12:15:54 -0700, gwhite
wrote:



nospam wrote:

Also I'm gonna stop using latex tubes because I feel it is easier for
'tube inclusions' to occur.

I too have noted a great deal of "inclusion difficulty" with certain
combinations of tires and latex
tubes. At times I found it extremely difficult to get the latex tubes
installed correctly because
they seemed to "stick" to the tire and not "want" to get seated properly
inside the tire. Different
amounts of air volume was tried to help form and unform the tubes in the
hope the technique would
help -- it was mostly to no avail.

The simplest and most effective way to keep the tubes from sticking in
the wrong position
(specifically getting stuck under the tire bead), was to talc the
combination before installation.
Then the tubes don't stick to the tire while trying to get them
installed. Just note that "talcing
tubes/tires," as an issue, has a religious fervor associated with it. As
best I can tell, it rarely
matters one way or the other whether one does or does not do it. That
said, in this specific case,
it seemed to greatly help get the tubes seated properly. I have never
noted a situation with butyl
tubes where the effect was so strongly pronounced as that with latex
tubes. So another way of
"solving the problem" is to only use butyl tubes, as you noted.