9th Blow-Out, Back to Dahon!

"Elisa Francesca Roselli" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

All our hopes and solutions have come to naught. James was here just on
Saturday to examine my 8th blow-out and try to find a solution. But there
just isn't one. No matter how many layers of rim-tape.

The 9th blow-out occured on my trip to work this morning. It is the second
blow-out since last week on the back wheel, which used to be the front
wheel; in other words, the great majority of blow-outs are all on the same
wheel whatever its position on the bike. Luckily I had not gone far, and I
was able to walk home in about 20 minutes. As soon as my boss is
operational (it's only 7:30) I will phone in and ask for an RTT. I can go
in to work by bus of course, but I need to find a solution to this problem
before Saturday, even if it means going back to the UK.

I think it's time to raise the issue with Dahon. The bike should have a
lifetime guarantee. It is currently unrideable, expert attention cannot
make it rideable, and a vacation tour costing over 700€ hangs in the
balance. I will ask for a replacement wheel. I feel it is owed. I ask the
group, who has been following this drama since it started, to support me.

Unfortunately even if I do obtain redress in principle, I don't see how
the wheel can arrive by Saturday, since even with the most express of
deliveries,

Well hang on in there - surely you could beg, borrow or steal a wheel rather
than can your tour.

Elisa Francesca Roselli wrote on 12/07/2006 06:57 +0100:

Quoted message said:

All our hopes and solutions have come to naught. James was here just on
Saturday to examine my 8th blow-out and try to find a solution. But
there just isn't one. No matter how many layers of rim-tape.

Whatever it is it would seem to not be the rim tape or spoke heads and
adding more rim tape is simply ignoring the evidence that it is not the
rim tape. There is clearly something on your wheel causing the
punctures that has not been spotted yet. Have you looked at where the
punctures occur relative to the valve hole and the tyre labels? If they
are always in the same position relative to the valve hole then it is
something on the rim and you will know exactly where to look. If it
varies relative to the valve hole but fixed relative to the tyre label,
it is something inside the tyre. You may need to look very closely.
Sharp thorns can get buried in the rubber and the heads break off so
they are not easily visible. Rims can have burrs or sharp edges that
are not immediately obvious but quickly wear a cut. Is it a small hole
or a cut in the inner tube? Whatever it is there is a clear cause or
Dahon would be out of business. You just haven't found it yet.

--
Tony

"Anyone who conducts an argument by appealing to authority is not using
his intelligence; he is just using his memory."
- Leonardo da Vinci

Elisa Francesca Roselli said:

I could also go on the vacation and not cycle. If there were some van support I might have made
it but I cannot set out on a rented bike with a prospect of 50 hilly kms
in front of me, 33 degree weather and no backup.

Obviously I know nothing at all about the rental possibilities around
you, but it does seem to me that renting another bike would be much
better than blowing the holiday. 50 kms, even with hills, is not so
very far and a bike with suitable gears (even if it took you a little
while to get used to using them) should let you cope well enough even in
33 degrees. I realise this is easy to say sitting here, but I do hope
you don't have to abandon just because of a seriously misbehaving wheel.

--
Brian G

Brian G said:

Elisa Francesca Roselli wrote:

Quoted message said:

Obviously I know nothing at all about the rental possibilities around
you, but it does seem to me that renting another bike would be much
better than blowing the holiday. 50 kms, even with hills, is not so
very far and a bike with suitable gears (even if it took you a little
while to get used to using them) should let you cope well enough even in
33 degrees. I realise this is easy to say sitting here, but I do hope
you don't have to abandon just because of a seriously misbehaving wheel.

I've had a holiday with a rented bike before and my response is "never
again". There was just far too much pain. It takes me many months to get
used to a bike, and I had two before the Dahon that I gave up on because
I never got comfortable riding them. Forty kms downhill is my current
max in a day, so I don't see myself doing 50 km uphill without a backup.
Besides which I cannot even mount a bike unless it has a very low
step-through. My Czech tour this spring offered very high-end
Cannondales as part of the package and it's just as well I went through
the hassle of bringing my own bike because I couldn't even get _on_ the
Cannondales.

21-gear bikes are offered as part of the package with the tour, and I
will keep them in mind as a last resort, but no, I do not envisage
touring on a rented bike.

EFR
Ile de France

"Tony Raven" <[email hidden]> a écrit:

Quoted message said:

Whatever it is it would seem to not be the rim tape or spoke
heads and adding more rim tape is simply ignoring the evidence
that it is not the rim tape. There is clearly something on your
wheel causing the punctures that has not been spotted yet.

The initial failures I saw were where the tube had puckered around the spoke
nipples, and the thick rim tape now in place was an attempt to reduce the
peak stresses on the tube in the already overstressed (because of the odd
tube profile) portion in the rim well.

The first improvised modification to the front rim tape seemed to have
helped (Elisa went from having one flat per day at the front to one per
month), so we applied a more permanent thick rim tape, first to the front
wheel (which has held up fine thus far), and on Saturday while replacing the
broken spoke in the rear wheel, I did the same to the rear.

Since then there've been two flats in the rear wheel - Monday's near the
valve, and today's about six inches from it.

Quoted message said:

Have you looked at where the punctures occur relative to the valve
hole and the tyre labels? If they are always in the same position
relative to the valve hole then it is something on the rim and you
will know exactly where to look. If it varies relative to the valve
hole but fixed relative to the tyre label, it is something inside the
tyre.

There's no consistency of location of the punctures relative to either the
rim or the tyre, except that all the punctures are rim-side. There's no burr
or irregularity on either rim, and no foreign object in either tyre.

Quoted message said:

Whatever it is there is a clear cause or Dahon would be out of
business. You just haven't found it yet.

Why would Dahon be out of business?

Dahon used this particular rim on only a few models, no longer use it at
all, and problems of this type with this rim are common (see the Dahon
forum). That there's clearly a cause doesn't mean that there's a clear
cause.

James Thomson

"Tony Raven" <[email hidden]> a écrit:

Quoted message said:

Whatever it is it would seem to not be the rim tape or spoke
heads and adding more rim tape is simply ignoring the evidence
that it is not the rim tape. There is clearly something on your
wheel causing the punctures that has not been spotted yet.

The initial failures I saw were where the tube had puckered around the spoke
nipples, and the thick rim tape now in place was an attempt to reduce the
peak stresses on the tube in the already overstressed (because of the odd
rim profile) portion in the rim well.

The first improvised modification to the front rim tape seemed to have
helped (Elisa went from having one flat per day at the front to one per
month), so we applied a more permanent thick rim tape, first to the front
wheel (which has held up fine thus far), and on Saturday while replacing the
broken spoke in the rear wheel, I did the same to the rear.

Since then there've been two flats in the rear wheel - Monday's near the
valve, and today's about six inches from it.

Quoted message said:

Have you looked at where the punctures occur relative to the valve
hole and the tyre labels? If they are always in the same position
relative to the valve hole then it is something on the rim and you
will know exactly where to look. If it varies relative to the valve
hole but fixed relative to the tyre label, it is something inside the
tyre.

There's no consistency of location of the punctures relative to either the
rim or the tyre, except that all the punctures are rim-side. There's no burr
or irregularity on either rim, and no foreign object in either tyre.

Quoted message said:

Whatever it is there is a clear cause or Dahon would be out of
business. You just haven't found it yet.

Why would Dahon be out of business?

Dahon used this particular rim on only a few models, no longer use it at
all, and problems of this type with this rim are common (see the Dahon
forum). That there's clearly a cause doesn't mean that there's a clear
cause.

James Thomson

Elisa Francesca Roselli said:

21-gear bikes are offered as part of the package with the tour, and I
will keep them in mind as a last resort, but no, I do not envisage
touring on a rented bike.

Perhaps the bikes are compatable with your current saddle...

Have you removed the rim tape and looked at each spoke at the nipple
inside the rim? I had a wheel that would flat evertime I rode it and
it too was inconsistant to position until i removed the rrim tape and
noticed there was a small aluminum shard that had developed when the
wheel was trued and during riding compression at a certain point would
puncture thru the rim tape into the tube. It would occur too often
when the tire pressure was just alittle low. finally found the culprit
and removed the shard and everything seems to be good.

James Thomson said:

"Tony Raven" <[email hidden]> a écrit:

Quoted message said:

Whatever it is it would seem to not be the rim tape or spoke
heads and adding more rim tape is simply ignoring the evidence
that it is not the rim tape. There is clearly something on your
wheel causing the punctures that has not been spotted yet.

The initial failures I saw were where the tube had puckered around the spoke
nipples, and the thick rim tape now in place was an attempt to reduce the
peak stresses on the tube in the already overstressed (because of the odd
rim profile) portion in the rim well.

The first improvised modification to the front rim tape seemed to have
helped (Elisa went from having one flat per day at the front to one per
month), so we applied a more permanent thick rim tape, first to the front
wheel (which has held up fine thus far), and on Saturday while replacing the
broken spoke in the rear wheel, I did the same to the rear.

Since then there've been two flats in the rear wheel - Monday's near the
valve, and today's about six inches from it.

Quoted message said:

Have you looked at where the punctures occur relative to the valve
hole and the tyre labels? If they are always in the same position
relative to the valve hole then it is something on the rim and you
will know exactly where to look. If it varies relative to the valve
hole but fixed relative to the tyre label, it is something inside the
tyre.

There's no consistency of location of the punctures relative to either the
rim or the tyre, except that all the punctures are rim-side. There's no burr
or irregularity on either rim, and no foreign object in either tyre.

Quoted message said:

Whatever it is there is a clear cause or Dahon would be out of
business. You just haven't found it yet.

Why would Dahon be out of business?

Dahon used this particular rim on only a few models, no longer use it at
all, and problems of this type with this rim are common (see the Dahon
forum). That there's clearly a cause doesn't mean that there's a clear
cause.

James Thomson

Elisa Francesca Roselli wrote:

I think the only definitive solution is to get the wheels rebuilt with a
different rim. Although they push people away with advice just to change
the rim tape, Dahon are clearly aware of the problem, which must be why
they tacitly withdrew this kind of rim from the market.

I spoke to Mark Bickerton in the UK - there is clearly nothing that can
be done in time for the trip. I will bring all my remaining tubes and
spokes with me and hope for the best.

I'm now having another problem with a very warped tyre. After so many
blow-outs and wheeling about uninflated it is now so assymetrical that
it is almost impossible to get it to seat properly. I seat it carefully
all around but as soon as it is inflated, I see the tyre popping out of
the rim or the beading at a very irregular distance from the rim. I
deflated and inflated about 4 times trying to sort this out without
success. So I may have to order a new tyre too (Bicloune doesn't stock
them, I just called to ask).

And of course the Polar HRM doesn't work on this model of bike -
distance between the receiver and the transmitter too great because of
the 20" wheels. I called the service center in Biarritz only to hear the
usual refrain of "we never hear of this kind of problem". (Decidedly the
French only ride standardized bikes, just as they are ultra-conventional
in every other domain). So I will have to use my old HRM for the trip,
because it will take at least a month to send the cadence and speed
captors all the way to Biarritz to have the range readjusted, and even
then there is no guarantee that the units will work.

Sheesh, is this ever a Retrogradation! Well, at least I'm getting a lot
of practise in bike maintenance. Thanks for all the tutorials, James - I
can now change both front and back wheels on my own.

EFR
Ile de France

In article <[email hidden]>,

Elisa Francesca Roselli said:

Elisa Francesca Roselli wrote:

I think the only definitive solution is to get the wheels rebuilt with a
different rim. Although they push people away with advice just to change
the rim tape, Dahon are clearly aware of the problem, which must be why
they tacitly withdrew this kind of rim from the market.

I spoke to Mark Bickerton in the UK - there is clearly nothing that can
be done in time for the trip. I will bring all my remaining tubes and
spokes with me and hope for the best.

snip

I looked at rebuilding with a different rim: problem is finding a 28H
rim. Only Sun seem to do one at £30+ each. What did Mark Bickerton say?
Fisher now distribute Dahon in the UK.

"Elisa Francesca Roselli" <[email hidden]> a écrit:

Quoted message said:

I'm now having another problem with a very warped tyre. After so
many blow-outs and wheeling about uninflated it is now so assymetrical
that it is almost impossible to get it to seat properly. I seat it
carefully all around but as soon as it is inflated, I see the tyre popping
out of the rim or the beading at a very irregular distance from the rim. I
deflated and inflated about 4 times trying to sort this out without
success. So I may have to order a new tyre too (Bicloune doesn't
stock them, I just called to ask).

It wouldn't be a bad idea to have a couple of spares in the garage just in
case.

The rear tyre was a little awkward to seat, but I think the reflective strip
being not quite concentric with the bead makes the problem appear worse than
it is. Sometimes soapy water is recommended as a lubricant to help coax
stubborn tyres to seat correctly. It's an old trick used by Moulton riders
whose 17" rims are often a little too big for their 17" tyres.

Incidentally, Googling for another local source of tyres I came across these
guys:

http://www.bicycland.com/velo-pliant-pliable-dahon.html

Is this where you bought Behemoth?

Bonne route.

James Thomson

"mrbubl" <[email hidden]> a écrit:

Quoted message said:

Have you removed the rim tape and looked at each spoke at
the nipple inside the rim?

Yes, front and rear. The only unusual feature was a light marking of the
inner rim face at one point where the motorised nipple driver used at the
factory had slipped out of engagement, but that's well covered by the rim
tape, and doesn't correspond to the tube failures Elisa experienced.

Quoted message said:

I had a wheel that would flat evertime I rode it and it too was
inconsistant
to position until i removed the rim tape and noticed there was a small
aluminum shard that had developed when the wheel was trued and
during riding compression at a certain point would puncture thru the
rim tape into the tube.

A good suggestion, but I'm certain that's not the problem here.

James Thomson

James Thomson said:

"Tony Raven" <[email hidden]> a écrit:

Quoted message said:

Whatever it is it would seem to not be the rim tape or spoke
heads and adding more rim tape is simply ignoring the evidence
that it is not the rim tape. There is clearly something on your
wheel causing the punctures that has not been spotted yet.

The initial failures I saw were where the tube had puckered around the spoke
nipples, and the thick rim tape now in place was an attempt to reduce the
peak stresses on the tube in the already overstressed (because of the odd
tube profile) portion in the rim well.

The first improvised modification to the front rim tape seemed to have
helped (Elisa went from having one flat per day at the front to one per
month), so we applied a more permanent thick rim tape, first to the front
wheel (which has held up fine thus far), and on Saturday while replacing the
broken spoke in the rear wheel, I did the same to the rear.

Since then there've been two flats in the rear wheel - Monday's near the
valve, and today's about six inches from it.

Quoted message said:

Have you looked at where the punctures occur relative to the valve
hole and the tyre labels? If they are always in the same position
relative to the valve hole then it is something on the rim and you
will know exactly where to look. If it varies relative to the valve
hole but fixed relative to the tyre label, it is something inside the
tyre.

There's no consistency of location of the punctures relative to either the
rim or the tyre, except that all the punctures are rim-side. There's no burr
or irregularity on either rim, and no foreign object in either tyre.

Quoted message said:

Whatever it is there is a clear cause or Dahon would be out of
business. You just haven't found it yet.

Why would Dahon be out of business?

Dahon used this particular rim on only a few models, no longer use it at
all, and problems of this type with this rim are common (see the Dahon
forum). That there's clearly a cause doesn't mean that there's a clear
cause.

James Thomson

Dear James,

Were the initial puckerings and the rim-side tube burst something like
these low-quality pictures?

http://home.comcast.net/~carlfogel/download/tubebump.jpg

http://home.comcast.net/~carlfogel/download/tubebump2.jpg

Cheers,

Carl Fogel

<[email hidden]> a écrit:

Quoted message said:

Dear James,

Quoted message said:

Were the initial puckerings and the rim-side tube burst something
like these low-quality pictures?

Quoted message said:

http://home.comcast.net/~carlfogel/download/tubebump.jpg

Quoted message said:

http://home.comcast.net/~carlfogel/download/tubebump2.jpg

Dear Carl,

The puckering of the tubes I saw initially before reinforcing the rim tape
looked not unlike the first picture, but corresponded to spoke nipple
locations in the rim bed.

The second picture is a dead ringer for Monday's blow-out, with a pucker to
one side of the valve, and a puckered longitudinal rupture to the other.

James Thomson

James Thomson said:

<[email hidden]> a écrit:

Quoted message said:

Dear James,

Quoted message said:

Were the initial puckerings and the rim-side tube burst something
like these low-quality pictures?

Quoted message said:

http://home.comcast.net/~carlfogel/download/tubebump.jpg

Quoted message said:

http://home.comcast.net/~carlfogel/download/tubebump2.jpg

Dear Carl,

The puckering of the tubes I saw initially before reinforcing the rim tape
looked not unlike the first picture, but corresponded to spoke nipple
locations in the rim bed.

The second picture is a dead ringer for Monday's blow-out, with a pucker to
one side of the valve, and a puckered longitudinal rupture to the other.

James Thomson

Dear James,

The puckering in the low-quality pictures is to either side of spoke
nipple in the rim bed.

I'm afraid there's a lot of silli--er, digression in the thread below,
but Dianne and Werehatrack had some ideas about what happened.

http://groups.google.com/group/rec.bicycles.tech/browse_frm/thread/35007cf54e3dd2d3/15b823be155e9e1f?lnk=st&q=yikes+-benjamin+author%3Acarlfogel%40comcast.net&rnum=4&hl=en#15b823be155e9e1f

or

http://tinyurl.com/q7zqc

Briefly, I went out one morning for the regular 4-mile ride and found a
rear flat on a $57.71 WalMart mountain bike that was being ridden for a
thousand miles on a dare.

Exposed spoke nipples in simple non-box U-curve rim, covered with a
rubber rim strip,
two-inch wide 26-inch wheels with monstrous knobby tires at about 55
psi.

The rim-side surface of the tube showed dimpling over the covered spoke
nipple heads, none of which had any spoke protruding--in the picture,
the dimple is in the middle, with a hump on either side.

The tube burst either very late in the short ride or else overnight, a
tiny triangular flap between a dimple and the Schrader valve stem,
after 640 miles. The replacement tube
(from Nashbar) lasted another 560 miles or so, with a switch to slick
tires, followed by honorable retirement.

Dianne had a theory about the problem, while Werehatrack mentioned
similar experiences and a two-rim-strip solution that involved holes in
one rim strip over the exposed spoke nipple heads.

I posted here because an email asked if I'd seen the thread and if the
Fury RoadMaster saga had included a similar disaster. The puckering,
rim design, and rim-side failure sounds similar, but the Dahon seems to
suffer far more of these odd tube failures. The puckering over the
spoke nipples may stretch the tube in a fashion that leaves a tiny
portion of the inflated rubber inner tube unsupported and prone to
fatigue, absurd as it may sound.

Cheers,

Carl Fogel

James Thomson said:

"Elisa Francesca Roselli" <[email hidden]> a écrit:

Incidentally, Googling for another local source of tyres I came across
these

Quoted message said:

guys:

http://www.bicycland.com/velo-pliant-pliable-dahon.html

Is this where you bought Behemoth?

Yes, a very nice shop in the 16th arrondissement, specializing in
"comfort" and Dutch bikes, but devilish to get to from here. With
Behemoth operational, it was tube to Cité Universitaire and ride from
there through the 15th but sometimes the traffic makes it too dangerous.
Otherwise it's 3 changes of tube with a lot of long, steep staircases,
so impractical for carrying a bike. However, if they have my tyres in
stock it's worth a visit. I'll give them a call.

EFR
Ile de France

James Thomson said:

http://www.bicycland.com/velo-pliant-pliable-dahon.html

I just phoned them. They have the tyre, but they're out of inner tubes.
And the shop in the 12th closed long ago. Still, it's great to know that
there is at least one shop in Paris ready to support Dahons. This is new.

However, when I asked the guy how much it would cost me to rebuild the
wheel he asked me why not just buy a new bike. Not very encouraging.

EFR
Ile de France

"Elisa Francesca Roselli" <[email hidden]> a écrit:

Quoted message said:

With Behemoth operational, it was tube to Cité Universitaire
and ride from there through the 15th but sometimes the traffic
makes it too dangerous. Otherwise it's 3 changes of tube with
a lot of long, steep staircases, so impractical for carrying a bike.
However, if they have my tyres in stock it's worth a visit. I'll give
them a call.

It seems they speak Dahon, so as well as tyres they may be useful for other
spares longer term. If access is a problem, you can always order parts
through them and I can ferry them out to you as and when. Likewise for
Bicloune.

James Thomson

Quoted message said:

I went out one morning for the regular 4-mile ride and found a
rear flat on a $57.71 WalMart mountain bike that was being ridden for a
********thousand miles******** on a dare.

Quoted message said:

The tube burst [...] after 640 miles. The replacement tube
(from Nashbar) lasted another 560 miles or so

1200 miles? You obviously liked it then. :-)