Homemade U-lock rack support

On 2018-08-13 14:46, Jeff Liebermann wrote:
On Mon, 13 Aug 2018 12:13:05 -0700, Joerg
wrote:

On 2018-08-13 11:34, Jeff Liebermann wrote:
On Mon, 13 Aug 2018 10:29:44 -0700, Joerg
wrote:

On 2018-08-13 08:27, Tanguy Ortolo wrote:
Frank Krygowski, 2018-08-13 17:11+0200:
Nice. If the appearance was bothersome, you could use a black tube held
in place with black zip ties.

Black tube, yes, if I can find some, but I only ever saw white tube in
hardware stores. Black zip ties, no, bad idea, as they let the tube
slide on the sides. I would rather use some black tape.

Zip ties are also bad in terms of reliability. It seems UV rays
embrittle them and then they just fall off. A while ago I chased and
stopped an MTB rider whose rear brake hose had come loose because of
that and was chafing on the rear wheel. Luckily I always have a snippet
of wire in my tool kit. Zip ties, too, but those only for temporary fixes.

You can buy UV resistant zip ties. They're loaded with carbon black
that blocks UV. However, not all such zip ties are equally resistant
to UV. Some of the cheap junk has much less than the recommended 2%
carbon black. After having an antenna installation fall apart in
about a year due to crumbling zip ties, I bought some that are genuine
Polyamide 6.6 UV resistant per ASTM D-4066PA411. No problems so far
after about 5 years:
https://www.hellermanntyton.us/bundling-securing/cable-ties/standard-cable-ties-special-materials/
https://www.hellermanntyton.us/resources/materials
https://www.solarpowerworldonline.com/2016/03/not-all-uv-rated-cable-ties-have-long-lifespans-on-solar-projects/

The one that popped was the stock tie from a high-Dollar Specialized
MTB. I can't imagine them being cheap on zip ties. Metal is generally
better.

I can believe it, if the big $$$$ specialized MTB builder trusted the
data sheets without testing. I had the same problem. The junk I
bought at the local hardware store said "UV resistant" on the package,
but wasn't. In order to test, polyamide (nylon) 6.6 should dissolve
in sulfuric acid. (I haven't tried this). The residue should be
mostly carbon black. By weighing everything, you can get a rough
guess for how much carbon black was used.
https://www.researchgate.net/post/What_is_the_solvent_to_solubilize_the_Polyamideexp ect_HFIP
Or, pay the price and use a proper tester:
http://www.testing-instruments.com/carbon-black-content-apparatus/


Or just use wire and be done with it. Not every little job has to turn
into a science experiment :-)

An experienced dirt bike rider told me that only a few things are
essential. Rum, duct tape, bailing wire. In that order.

--
Regards, Joerg

http://www.analogconsultants.com/