6th Tube Blows

Artemisia said:

Alas, after a heroic intervention from James Thompson and almost a
month of happy cycling, I am moritfied to report that Flyzipper has
started blowing his inner tubes again.

I had so hoped that James' solution of adding layers of rim protection
would have solved the problem for good.

Last night's blow out was inaudible or at least unheard by me. I was
wheeling Fly on a walked section of the homeward trip and noticed that
the front wheel was flat. The hole, this time, is so small that I had
trouble finding it, barely a pinprick right next to the valve.
Previous blow-outs have all been either directly opposite, or right
next to the valve like this one, and all have been on the rim side of
the tube, but they generally have been much larger, about a half-inch
long and ragged. As previously, the outer tyre is intact and the
inside of it is smooth and empty.

Being optimisitic, maybe this latest problem is a bit different, or
otherwise whatever cause is behind it has been somewhat solved and there's
just a little bit more work left to do....

The area either side of the valve is relatively vulnerable with all tubes
in all wheels, hence the reinforcement pad, or thicker bit of butyl,
around the valve on the tube. If the ones on your tubes are small and
round, you'd be better off either finding an alternative brand of tube
with large oval reinforcements, or with new tubes of the same brand,
sticking puncture repair patches either side of the valve to add some
protection.

I've had this problem (small holes to side of valve for no good reason)
with Vredestein Race and Continental Supersonic tubes used at high
pressure. They both have too-small reinforcement pads.

~PB

It might also be worth very lightly twirling a large drill bit on the
inside of the valve hole (by fingers only) to chamfer the edge a wee
bit just in case there's a slight burr from the original hole cutting
process.

Might also be useful to cut an oval from an old tube (1" x 3/4" say)
with a hole just large enough to poke the valve through and just slide
it over the valve to protect the area ajacent to it (no need to glue).

I'd try different makes of tube as well (well known brands) of the
right size for the tyre (OK, maybe that's a bit obvious, sorry).

Also, you might want to leave the securing nut off (the one that spins
over the valve after inatallation and tightens on the outside of the
rim) as fitting this prevents you from seeing if the tube is moving
inside the tyre and will often deflate suddenly as it rips the valve
partially out. I've run for donkeys years and many tens of thousands of
miles without these wee locking rings.

Robert

BigRab a écrit :

Quoted message said:

Might also be useful to cut an oval from an old tube (1" x 3/4" say)
with a hole just large enough to poke the valve through and just slide
it over the valve to protect the area ajacent to it (no need to glue).

Great idea! I certainly have plenty of old tubes to cut it from!

Quoted message said:

I'd try different makes of tube as well (well known brands) of the
right size for the tyre (OK, maybe that's a bit obvious, sorry).

Alas, there aren't that many choices as this size of tube is really hard
to find in France. The ones that James brought me are Schwalbe, and the
ones I ordered from Dahon were some other make, but very expensive. The
one that blew last night was Schwalbe and I replaced it with a Dahon,
but I've had these blow-outs on both kinds.

Quoted message said:

Also, you might want to leave the securing nut off (the one that spins
over the valve after inatallation and tightens on the outside of the
rim) as fitting this prevents you from seeing if the tube is moving
inside the tyre and will often deflate suddenly as it rips the valve
partially out.

Done, in fact the Dahon tubes don't have that little nut, although the
Schwalbes do.

Thanks for your suggestions. I shall be praying and offering libations
to the Deities all week.

EFR
Ile de France

"Artemisia" wrote: (clip) The hole, this time, is so small that I had
trouble finding it, barely a pinprick right next to the valve. Previous
blow-outs have all been either directly opposite, or right next to the
valve like this one, and all have been on the rim side of the tube, but
they generally have been much larger, about a half-inch long and ragged.
(clip)
^^^^^^^^^^^^^^^^
A "blowout" is a sudden loss of air through a rip or large hole in the tube.
That is consistent with your description of the previous failures. What you
are describing now, as a leak through a hole so small you had a hard time
finding it, is NOT a blowout. My point is that you are not on a
continuation of the old series of failures. This is something different,
which is good news. Look for a burr or anything that could produce a small
hole. It is even possible that the tube already had an incipient leak, and
it took a month of riding to bring it out.

In article <[email hidden]>, Artemisia <[email hidden]>

Quoted message said:

Alas, after a heroic intervention from James Thompson and almost a month
of happy cycling, I am moritfied to report that Flyzipper has started
blowing his inner tubes again.

Could there be something fundamentally jinxed with that wheel? Might it
be worth it to order a whole new front wheel from Dahon?

EFR

Saddened and stymied in Ile de France

Which model Dahon do you have. This is a well known fault with the 2004
Helios P8 which has very deep aero rims, Kinetix Aero, a stupid, stupid,
stupid design. There are dozens of postings about this on the Dahon
forum. I bought 2 of these bikes 2 years ago and have yet to put 50
miles on either of them; pump the tyre up to half the rec pressure and
30 minutes later bang, a large tear on the inside of the rim. This is
with 2 layers of Velox tape and 1 layer of rubber tape. The bikes are
not fit for purpose but so far Dahon have not resolved the matter. The
only solution is to scrap the rims and rebuild the wheels with new rims
which leads to the next problem; 28 hole 406 rims are next to impossible
to find (discounting SJS silly price Sun ones at £30 each). Very
disappointed, and seriously out of pocket.

Twangin said:

Which model Dahon do you have. This is a well known fault with the
2004 Helios P8 which has very deep aero rims, Kinetix Aero, a stupid,
stupid, stupid design. There are dozens of postings about this on the
Dahon forum. I bought 2 of these bikes 2 years ago and have yet to
put 50
miles on either of them; pump the tyre up to half the rec pressure and
30 minutes later bang, a large tear on the inside of the rim. This is
with 2 layers of Velox tape and 1 layer of rubber tape. The bikes are
not fit for purpose but so far Dahon have not resolved the matter. The
only solution is to scrap the rims and rebuild the wheels with new
rims

Or stuff some filling in the rims, as has been done already in this case
(although maybe it's still not enough filling).

~PB

Twangin' a écrit :

Quoted message said:

Which model Dahon do you have. This is a well known fault with the 2004
Helios P8 which has very deep aero rims, Kinetix Aero, a stupid, stupid,
stupid design. There are dozens of postings about this on the Dahon
forum.

Oh dear! My Dahon is an Impulse P21, a model which they have apparently
discontinued, but I'm not sure about the wheel and I think it may be
Kinetix too. Do you have a link to the Dahon forum you are describing? I
haven't been in a Dahon forum yet and would like to follow up this lead.

EFR
Ile de France

In article <twanginman-497C62.20154813062006@i-194-106-32-
13.freedom2surf.net>
<snip>

Quoted message said:

Which model Dahon do you have. This is a well known fault with the 2004
Helios P8 which has very deep aero rims, Kinetix Aero, a stupid, stupid,
stupid design. There are dozens of postings about this on the Dahon
forum. I bought 2 of these bikes 2 years ago and have yet to put 50
miles on either of them; pump the tyre up to half the rec pressure and
30 minutes later bang, a large tear on the inside of the rim. This is
with 2 layers of Velox tape and 1 layer of rubber tape. The bikes are
not fit for purpose but so far Dahon have not resolved the matter. The
only solution is to scrap the rims and rebuild the wheels with new rims
which leads to the next problem; 28 hole 406 rims are next to impossible
to find (discounting SJS silly price Sun ones at £30 each).

If that's the case would it not be easier to fill the vee of the rim
with something like polyester filler or silicone sealant?

In article <[email hidden]>,

Artemisia said:

Twangin' a écrit :

Quoted message said:

Which model Dahon do you have. This is a well known fault with the 2004
Helios P8 which has very deep aero rims, Kinetix Aero, a stupid, stupid,
stupid design. There are dozens of postings about this on the Dahon
forum.

Oh dear! My Dahon is an Impulse P21, a model which they have apparently
discontinued, but I'm not sure about the wheel and I think it may be
Kinetix too. Do you have a link to the Dahon forum you are describing? I
haven't been in a Dahon forum yet and would like to follow up this lead.

EFR
Ile de France

Kinetix is I think one of Dahon's own brands. The Dahon forum is at
http://www.dahon.com/forum/index.php. Be aware that it will crash Safari
browser but is ok with IE.

Here's a couple of threads;

http://www.dahon.com/forum/index.php?showtopic=616&hl=
http://www.dahon.com/forum/index.php?showtopic=753&hl=

Twangin' a écrit :

Quoted message said:

http://www.dahon.com/forum/index.php?showtopic=616&hl=
http://www.dahon.com/forum/index.php?showtopic=753&hl=

Thanks so much, I've found the threads and checked up the specs for my
model of bike. Right you are, Kinetix Aero wheels! I've written to my
dealer, World Wheels, who do Dahon in the UK, to see if they can do
anything about it. If not, I'll have to go the route of continuing to
stuff that cavity until the spoke dimpling on the tubes disappears.

I'm relieved at least to know that there is a precedent and a
diagnoseable disease.

EFR
Ile de France