rim heating and tube failure

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Bill Bushnell

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Oct 29, 2001, 6:40:34 PM10/29/01
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While descending a steep hill yesterday (Vista Verde Rd. just before the
stop sign at Los Trancos Woods Rd. in Portola Valley, CA), I experienced a
sudden loss of air from the tire. It was not a blowout. I managed to get
the wheel off the bike, but the rim was too hot to handle for about a
minute.

I discovered the failure, a 6mm slit, on the inside of the tube at one of
the spoke holes. The spoke hole in question was covered securely by Velox
cloth rim tape, but I did notice a peculiar stain at each of the spoke
holes on the wheel. I learned later that the gentleman who built my wheel
used linseed oil on the spoke threads during assembly, and that this stain
was probably linseed oil residue that had seeped into the rim tape. I
inspected the tube where it contacts the other spoke holes and discovered
that at each of these locations, the tube surface was crazed in the exact
area of each spoke hole where this linseed oil residue had saturated the
rim tape.

Equipment associated with failure:

rim: Ritchey OCR Pro
brake pads: Koolstop salmon
rim tape: Velox
tube: Ritchey 559x1.3
tire inflation pressure: 100 psi
tire: Primo Racer 559x1.5

I have descended this same hill several times before in the same fashion
using a different wheel and associated equipment and have not had this
problem.

Equipment associated with no failure:

rim: Ritchey OCR Comp
brake pads: Shimano XT V-brake
rim tape: Velox
tube: Cheng Shin 559x1.5
tire inflation pressure: 85 psi
tire: Ritchey Tom Slick 559x1.4

I would like to know what caused the failure so I can take steps to avoid
a similar failure in the future. Possible causes I can think of:

1) Slightly lighter OCR Pro rim gets hotter.
2) Thinner or poorer quality Ritchey tube.
3) Shimano V-brake pad conducts more heat from rim than Koolstop pad.
4) Linseed oil in cloth tape conducts heat from rim to tube, causing
failure.
5) Something I haven't yet thought of.

Which of these is the most likely cause of failure?

--
--Bill Bushnell

bush...@pobox.com

jobst....@stanfordalumni.org

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Oct 29, 2001, 8:31:25 PM10/29/01
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Bill Bushnell <mrb...@pobox.com> writes:

> While descending a steep hill yesterday (Vista Verde Rd. just before
> the stop sign at Los Trancos Woods Rd. in Portola Valley, CA), I
> experienced a sudden loss of air from the tire. It was not a
> blowout. I managed to get the wheel off the bike, but the rim was
> too hot to handle for about a minute.

> I discovered the failure, a 6mm slit, on the inside of the tube at
> one of the spoke holes. The spoke hole in question was covered
> securely by Velox cloth rim tape, but I did notice a peculiar stain
> at each of the spoke holes on the wheel. I learned later that the
> gentleman who built my wheel used linseed oil on the spoke threads
> during assembly, and that this stain was probably linseed oil
> residue that had seeped into the rim tape. I inspected the tube
> where it contacts the other spoke holes and discovered that at each
> of these locations, the tube surface was crazed in the exact area of
> each spoke hole where this linseed oil residue had saturated the rim
> tape.

You may have been swallowing or experiencing some other interference
with hearing but a slash of the kind you mention is invariably a
blowout. That the tube was cracked suggests that this was not a butyl
tube because they are not affected by vegetable oil... or motor oil
for that matter, heat and oil might have an effect but I haven't seen
it. You must have seen these before. The road you mention makes
plenty of heat to blow a tire from a rim. Had that not been enough,
you could have continued down Joaquin to make sure you could hear it.

> tire inflation pressure: 100 psi

Jobst Brandt <jobst....@stanfordalumni.org>

Bill Bushnell

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Oct 29, 2001, 9:23:14 PM10/29/01
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jobst....@stanfordalumni.org wrote:

> You may have been swallowing or experiencing some other interference
> with hearing but a slash of the kind you mention is invariably a
> blowout. That the tube was cracked suggests that this was not a butyl
> tube because they are not affected by vegetable oil... or motor oil
> for that matter, heat and oil might have an effect but I haven't seen
> it. You must have seen these before. The road you mention makes
> plenty of heat to blow a tire from a rim. Had that not been enough,
> you could have continued down Joaquin to make sure you could hear it.

Jobst, thanks for following up.

The sudden loss of air was accompanied not by a "POP!" but by a loud
hissing of alternating timbre the frequency of which matched that of the
rotation of the wheel. The tire took several seconds to go dead flat, and
it remained on the rim. If any rapid loss of air pressure is defined as a
blowout, then this event was.

Are you suggesting that if any equipment can be found contributing to this
event, then the innertube would be the most likely? I believe the tube is
a standard-issue Ritchey 559 tube and is butyl. Perhaps the material in
this particular tube is substandard, or perhaps the material is too thin.

--
--Bill Bushnell

bush...@pobox.com

Tom Kunich

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Oct 30, 2001, 9:40:35 AM10/30/01
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"Bill Bushnell" <mrb...@pobox.com> wrote in message
news:maoD7.10166$no1.1...@typhoon.sonic.net...

>
> Are you suggesting that if any equipment can be found contributing to
this
> event, then the innertube would be the most likely? I believe the
tube is
> a standard-issue Ritchey 559 tube and is butyl. Perhaps the material
in
> this particular tube is substandard, or perhaps the material is too
thin.

Bill, this is a curious failure and for someone of your experience to
not know what caused the problem is interesting. I would appreciate it
if you would keep us posted about your investigations.

news.sonnet.com

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Oct 30, 2001, 2:24:21 PM10/30/01
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It is stretch, but the culprit may be the Linseed Oil. As a full time
fireman, I have seen several fires caused by Linseed Oil creating heat as it
decomposes. Most of the time, oil soaked rags have been stacked so that the
head dosn't dissipate and it builds up until the material ignites.

It is possible that the linseed oil was already creating heat and that the
heat you added via break friction acclerated the process. Just a slightly
educated guess at this point.

Safety point for the day.... If you use linseed (or any organic oil) clean
up after and put the rags in a metal, air-tight container. These fires
really do happen! Don't them ruin your day.

Mike Borean

Bill Bushnell

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Oct 30, 2001, 5:27:41 PM10/30/01
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"Tom Kunich" <tku...@tality.com> wrote in message news:<3bdebc0a$1...@news.cadence.com>...

> Bill, this is a curious failure and for someone of your experience to
> not know what caused the problem is interesting. I would appreciate it
> if you would keep us posted about your investigations.

The primary cause was obviously the heat generated from braking. What
were the cause and effect chain of events that led from the rim
heating to the tube failure?

What I found curious is that the tube failed not at the rim/tire bead
interface but at a spoke hole, on the very portion of the rim tape
that had been saturated with linseed oil. Is there a contributory
effect? In particular, is there any validity to the hypothesis that
the oil conducted heat from the rim to the tube so that the tube was
weakened and failed precisely where it did? Would the tube have
failed otherwise?

I don't have much experience with blowouts on steep descents, perhaps
because I tend to make conservative choices with equipment. And I
don't have many miles with the particular tire/rim combination in
question (Primo Racer 559x1.5/Ritchey OCR Pro) that I have so far used
only for occasional timed or long events, none of which have included
steep descents with heavy braking.

I would like to increase my future margin of safety under these
conditions. The best answers so far seem to be:

1) Use a thicker or different tube. Another cyclist I know has
reported similar problems with the Ritchey tubes and thinks they're
unreliable. A closer inspection of the tube has revealed abrasions
and pitting in several places along the inside where it contacts the
rim tape. Additionally, the cloth pattern of the rim tape is
imprinted on the tube itself.
2) Inflate the tire a little less, perhaps 85-90 psi instead of the
max rated 100 psi. 100psi is quite high on a 1.5 inch tire.

--Bill Bushnell

Mark

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Oct 30, 2001, 5:36:07 PM10/30/01
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Bill Bushnell wrote:
>
>
> What I found curious is that the tube failed not at the rim/tire bead
> interface but at a spoke hole, on the very portion of the rim tape
> that had been saturated with linseed oil. Is there a contributory
> effect? In particular, is there any validity to the hypothesis that
> the oil conducted heat from the rim to the tube so that the tube was
> weakened and failed precisely where it did? Would the tube have
> failed otherwise?

Or perhaps the tube was weaker at the areas that had been exposed to
linseed oil (you mentioned that there was "crazing" at each of the spoke
holes, in the stained areas). When the tube was heated by the braking
maybe it just failed at a weak spot.

If that's the case, using a different tube that isn't as susceptible to
the linseed oil or changing the rim tape to get rid of some of the
linseed oil might help the problem.

Mark
mdw...@myriad.net

David Ornee

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Oct 30, 2001, 7:41:04 PM10/30/01
to
I agree with Mark:
Change out the rim tape, cleanout any excess oils that may be in the rim
cavity. While cleaning the rim it is a good idea to check for and clean
away any burrs around the spoke holes.
Install a high quality tube that is sized for the application.
You might want to check the tandem@hobbs group for additional insights as
the rim heating discussions surface often amongst tandem riders.
David Ornee, Western Springs, IL
"Mark" <mdw...@yahoo.com> wrote in message
news:3BDF2B57...@yahoo.com...

peter smith

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Oct 30, 2001, 7:47:15 PM10/30/01
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Bill Bushnell <mrb...@pobox.com> wrote in message news:<maoD7.10166$no1.1...@typhoon.sonic.net>...

A similar story: I descended a steep half paved, half dirt route off
Mt. Wilson to Altadena on my mtb with specialized's lightweight butyl
tubes on a hot day several years ago. The next day, both tubes gently
blew 6"-12" slits when I first tried to ride the bike.

Trevor Jeffrey

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Oct 30, 2001, 9:05:51 PM10/30/01
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I like it. A good reason to not use linseed oil on spoke threads. It may
contribute to tube deflation. Considering the failure point, it certainly
seems that way. More input is necessary.
--
Trevor M Jeffrey

Eat your greens before email.
------

Tom Kunich

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Oct 31, 2001, 9:04:01 AM10/31/01
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"Mark" <mdw...@yahoo.com> wrote in message
news:3BDF2B57...@yahoo.com...
> Bill Bushnell wrote:
> >
> >
> > What I found curious is that the tube failed not at the rim/tire
bead
> > interface but at a spoke hole, on the very portion of the rim tape
> > that had been saturated with linseed oil. Is there a contributory
> > effect? In particular, is there any validity to the hypothesis that
> > the oil conducted heat from the rim to the tube so that the tube was
> > weakened and failed precisely where it did? Would the tube have
> > failed otherwise?
>
> Or perhaps the tube was weaker at the areas that had been exposed to
> linseed oil (you mentioned that there was "crazing" at each of the
spoke
> holes, in the stained areas). When the tube was heated by the braking
> maybe it just failed at a weak spot.

The tube is butyl and vegetable oils such as linseed oil aren't supposed
to effect it. There isn't any motion in a fully inflated tube so some
sort of friction effect from the tube sticking to the linseed oil is
also unlikely. But Bill reported that the failure was a long tear which
indicates a lift-off failure. The only other source I could think of for
such a failure is some sort of local tube failure and if the tube was
stuck to the rim, perhaps removing the tire and tube tore the tube at
that point. However, Bill is a VERY experienced rider and would notice
such a thing I would think.

> If that's the case, using a different tube that isn't as susceptible
to
> the linseed oil or changing the rim tape to get rid of some of the
> linseed oil might help the problem.

There are only two types of material used in innertubes presently: butyl
and latex. Neither one is sensitive to vegetable oils.

Bill Bushnell

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Oct 31, 2001, 3:52:00 PM10/31/01
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"Tom Kunich" <tku...@tality.com> wrote in message news:<3be004f9$1...@news.cadence.com>...

> The tube is butyl and vegetable oils such as linseed oil aren't supposed
> to effect it. There isn't any motion in a fully inflated tube so some
> sort of friction effect from the tube sticking to the linseed oil is
> also unlikely. But Bill reported that the failure was a long tear which
> indicates a lift-off failure. The only other source I could think of for
> such a failure is some sort of local tube failure and if the tube was
> stuck to the rim, perhaps removing the tire and tube tore the tube at
> that point. However, Bill is a VERY experienced rider and would notice
> such a thing I would think.

I'm already convinced that there is no chemical reaction between the
tube and linseed oil to cause it to fail. What I am still not
convinced of is whether or not the oil may have conducted heat from
the rim, or perhaps the rim heat acted as a catalyst to the already
decomposing oil on the rim strip, as one poster suggested.

The tear was very short. I originally said 6mm, but that was a rough
estimate. I didn't actually measure it at the time. It looked much
like a pinch flat failure or a tear put in a tube from incompetent
installation, though I am also certain that there was no pinch flat as
I inflated the tire at home to 100 psi, and this was the only hole I
discovered in the tube. I had already ridden about 75 miles at that
point of the ride, so installation wasn't to blame.

The tube patched only at the known point of failure still holds air
several days later. The road in question is smooth with no rocks or
other hazards that could have caused a pinch flat. With a 1.5" tire
pumped to 100psi I would have had to ride over a brick at the speed I
was going (35-40 mph--didn't have a working speedometer) to get a
pinch flat. I think I would have noticed that.

The heat from or through the linseed oil weakening the tube or that
the tube was slightly weaker where it was perturbed at the uneven
contour of the rim tape over the spoke hole may have caused it to
fail--like a bubble gum bubble--at the moment the tire lifted off the
rim.

For now I'm assuming the most likely cause was overinflation, in spite
of the "100 psi" max pressure label on the sidewall. Using a thicker
tube may also reduce the likelihood of future occurrences.

--Bill

jobst....@stanfordalumni.org

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Oct 31, 2001, 5:11:06 PM10/31/01
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Bill Bushnell writes:

>> Bill, this is a curious failure and for someone of your experience to
>> not know what caused the problem is interesting. I would appreciate it
>> if you would keep us posted about your investigations.

> The primary cause was obviously the heat generated from braking. What
> were the cause and effect chain of events that led from the rim
> heating to the tube failure?

> What I found curious is that the tube failed not at the rim/tire bead
> interface but at a spoke hole, on the very portion of the rim tape
> that had been saturated with linseed oil. Is there a contributory
> effect? In particular, is there any validity to the hypothesis that
> the oil conducted heat from the rim to the tube so that the tube was
> weakened and failed precisely where it did? Would the tube have
> failed otherwise?

Even if the tube became exceedingly hot, it would not be near melting,
and since the tube does not contain the forces of inflation (the tire
and rim do that) Its oiliness or age has little effect. Latex
rubber, on the other hand, ages to the point of crumbling and can fail
as you suggest. The tube is merely an impervious barrier that has
almost not stress unless the tire lifts off the rim.

> I don't have much experience with blowouts on steep descents,
> perhaps because I tend to make conservative choices with equipment.
> And I don't have many miles with the particular tire/rim combination
> in question (Primo Racer 559x1.5/Ritchey OCR Pro) that I have so far
> used only for occasional timed or long events, none of which have
> included steep descents with heavy braking.

Blowouts or more precisely "blow-offs" are common on wheels that get
hot. That goes for single bicycle as well as tandems. The condition
where this occurs most readily is a steep descent that does not permit
coasting at higher speed between brake applications... steep rough dirt
roads as well as some straighter but continuously steep roads.

> I would like to increase my future margin of safety under these
> conditions. The best answers so far seem to be:

Ride 10psi lower pressure on such runs. That's the best and easiest.

> 1) Use a thicker or different tube. Another cyclist I know has
> reported similar problems with the Ritchey tubes and thinks they're
> unreliable. A closer inspection of the tube has revealed abrasions
> and pitting in several places along the inside where it contacts the
> rim tape. Additionally, the cloth pattern of the rim tape is
> imprinted on the tube itself.

That would have no effect because I still believe this was not one of
the many internal blowouts that are regularly reported here.

> 2) Inflate the tire a little less, perhaps 85-90 psi instead of the
> max rated 100 psi. 100psi is quite high on a 1.5 inch tire.

That's the one that works. Using a larger tire also helps because it
prevents a small volume of air from heating as quickly.

Jobst Brandt <jobst....@stanfordalumni.org>

jobst....@stanfordalumni.org

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Oct 31, 2001, 6:05:03 PM10/31/01
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Peter Smith writes:


>> The sudden loss of air was accompanied not by a "POP!" but by a
>> loud hissing of alternating timbre the frequency of which matched
>> that of the rotation of the wheel. The tire took several seconds to
>> go dead flat, and it remained on the rim. If any rapid loss of air
>> pressure is defined as a blowout, then this event was.

>> Are you suggesting that if any equipment can be found contributing
>> to this event, then the innertube would be the most likely? I
>> believe the tube is a standard-issue Ritchey 559 tube and is butyl.
>> Perhaps the material in this particular tube is substandard, or
>> perhaps the material is too thin.

> A similar story: I descended a steep half paved, half dirt route off
> Mt. Wilson to Altadena on my mtb with specialized's lightweight
> butyl tubes on a hot day several years ago. The next day, both
> tubes gently blew 6"-12" slits when I first tried to ride the bike.

If you herd the pop, the tube was outside the tire. On the other
hand, you didn't say who was around when the tubes blew out.

http://draco.acs.uci.edu/rbfaq/FAQ/68.html

Jobst Brandt <jobst....@stanfordalumni.org>

John Albergo

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Nov 3, 2001, 3:36:20 PM11/3/01
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Bill Bushnell wrote:

The crazing at the spoke holes seems significant. Something is going on
there (or once went on) whether it is heat conduction or chemical reaction or
something else. I'd expect the spoke hole area to be the coolest part of the
rim. In any case I'd say replacement of the rim tape is warranted. A
double-wrap of cloth tape will provide more thermal insulation if you can
still mount the tire. Thicker tube more durable in general, so why not.

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