On 2017-01-04 10:31, David Scheidt wrote:
Joerg wrote:
:On 2017-01-03 18:47, David Scheidt wrote:
: John B. wrote:
: :On Tue, 03 Jan 2017 17:04:40 -0800, Joerg
: :wrote:
:
: :Gentlemen,
: :
: :Is there something stronger than the usual rubber cement in the patch
: :kits? Ideally something that won't dry out so fast or where multiple
: :cheap small tubes are available.
: :
: :The reason is that I sometimes have larger holes from side wall
: :blow-outs. Not inch-long gashes but one or two tenths of an inch long.
: :The tubes I use are super thick and, therefore, expensive. $15-20 each
: :and that's not something to be thrown out lightly. Instead of the li'l
: :REMA patches I need to use thicker rubber from an older sacrified tube
: :but this has to be vulcanized/cemented really well.
:
: :My LBS usually has small sealed tubes of glue. When I see them I buy
: :four or five and when I open a sealed tube, in the kit on the bike, I
: :replace it with another sealed one as find the glue has dried up is
: :not quite so much of a catastrophe at home :-)
:
: :Or you might try contact cement what I suspect is what is in the usual
: :tire patching kit.
:
: :By the way, "vulcanizing" implies the use of heat, and sulphur, and I
:
: Vulcanizing may have the connotation of involving heat, but it's a chemical
: reaction, which results in the sulphur in the rubber becoming
: crosslinked.
:That's how I also remember it.
: ... Patches, at least the good ones such as Rema and park,
: are a multi-layered assembly. The top layers are for strength, the
: bottom (closest to the tube) consists of unvulcanized rubber, mixed
: with a vulcanizing ultra-accelerator (there are a number of zinc
: thiols that are suitable, which ones are used are trade secrets. ZDDP
: is typical, though). vulcanizing cement consists of a unvulcanized
: rubber particles, a solvent to carry them, and a vulcanizing
: activator. Cyclohexylamine is common, but there are others that will
: work, and are less toxic. The activator reacts with the zinc thiol,
: and causes the patch, the rubber in the cement, and the surface of
: tube to become vulcanized. There's not much free sulphur in the tube,
: because it's vulcanized, which is one of the reasons that it's
: important to properly scarify the tube surface before patching; it
: greatly increases the surface area of the patch. The reaction is not
: instant, but it happens pretty fast at room temperature, and
: continues for some time, until all the sulphur available has linke.d
:
:Ever since I began using REMA patches and the cement that comes with
:them my result were less stellar than in Europe with the classic kits.
:Those contain much thicker patches that looked like round chunks of
:tube, sometimes slightly beveled. Can't find those here in the US.
Rema patches in action:
https://scontent.ford4-1.fna.fbcdn.n...bb&oe=58E69CCC
https://scontent.ford4-1.fna.fbcdn.n...9c&oe=58E45D94
That tube is still in service, two years later.
Impressive. I wouldn't even have tried to repair that one.
One significant difference is that my tubes are much thicker in their
walls. 3mm on the road bike and 4mm on the MTB. So the tube material is
many times thicker than REMA patches.
:The question is why would be the good ones to buy?
I use rema f1, which are round and 25 mm in diameter. Box of 100
costs ~20 bucks. A half pint bottle of vulcanizing flouid, which will
do hundreds of patches, and last for years (mine has been in my dsk
for five years) costs ~$10 at an auto parts store (very expensive to
ship, buy local.).
Looks like it ships free if you get past $49 with all the other stuff to
be ordered:
https://www.amazon.com/STEELMAN-G101.../dp/B00NBTGCLS
The "Slime" brand is cheaper. Do you think the one below works as well?
I was not impressed with their self-healing tubes but this seems to be
other stuff.
https://www.amazon.com/Slime-1050-Ru.../dp/B003V9UU66
What we do is keep a tab on things that are needed elsewhere. Such as
espresso or (for bike riding) Ultima Replenisher electrolyte powder.
That is then used top fill orders beyond the $49 free-ship barrier.
Also, I'd like to cement on real (thicker) tube material instead of REMA
patches. Don't see a reason why this shouldn't be possible.
--
Regards, Joerg
http://www.analogconsultants.com/