On Sat, 27 Sep 2014 14:15:06 -0700, Joerg
wrote:

Tried in a European NG but no luck so far. I get a nasty-looking red
skin rash on my shoulders and upper chest where the main carrying straps
of by hydration pack run along. I generally cycle in a thin T-shirt
because I can't take anything other than cotton. Gets totally sweaty, of
course. The backpack is a Zefal hydration pack and weighs about 12lbs at
the start of a ride, about 6lbs at the end after most water is consumed.
The rides are usually 3-4h long, sometimes strenuous and on rough
offroad terrain so the backpack jumps a lot.

Thick cotton layers over the straps didn't help much. Does anyone else
have that problem? Any ideas what to do?

http://usa.zefal.com/hydrationpacks/
What are the straps and pads made from? Rubber? Latex? Polyester?
Leather? There should be a tag with washing instructions somewhere.

If the thick cotton wrap gets soaked with perspiration, then there
might be something soluble in the straps that is producing an allergic
reaction. To give the pads some liquid isolation, try trapping the
pads in cellophane wrap and then bury them under a layer of thick
cotton.

Replace the padding on the straps with something made from
anti-allergy cotton. The web photos look like they can be removed
without much surgery.

I had some allergy like rashes from my hiking backpack pads because I
used too much laundry detergent for cleaning, and didn't rinse it
sufficiently. The problem went away after a thorough rise in very hot
water.

Perhaps dust mites in the strap padding?

Get an all cotton baby carrier:
http://www.amazon.com/Carrier-Comfort-Backpack-Fashion-Adjustable/dp/B00EY8PV1W
Turn it around backwards, hang it on your back, insert water bag, add
plumbing, and you're done.

If you can run a sewing machine, make your own cotton straps and
padded covers.

Some cheap remedies:
http://www.active.com/cycling/articles/home-remedies-for-saddle-sores-and-chamois-rash


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558