fietsbob

The Fry eggs on the sidewalk is a lot lower temperature than melting nylon..

have you personally experienced this?

A big part of not having a bolt loosen is getting it tight enough in the first place, and then keeping
your wrenches handy and double checking them as part of regular service.

that statistics.. 160f ! is why I live where I Do ..

split washers or star, shake proof washers , inside star or outside?

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PlanoFuji

I am not talking about nylon melting away, but rather it softening and the nylock loosing effectiveness. And yes I have experienced this problem. That is why I use metal lock nut washers as insurance and carry spares of the nylocks, which I replace every other day when riding in those temperatures. Typically after a couple of days of riding in the summer in those temperatures, I can spin a nylock nut off by hand -- something I can't do if the nylon hasn't deformed due to the temperatures.

Frankly, I would also wonder how well the nylon would hold up to the opposite temperature extreme as well.

I think they are great products, but I consider them consumables that need to be replaced regularly. Where as metal lock washers, are nearly indestructible--I keep two types on hand at all times

https://www.mcmaster.com/#catalog/119/3206/=njpa9x
and
https://www.mcmaster.com/#catalog/119/3208/=njpal6

but I also use these, https://www.mcmaster.com/#catalog/119/3171/=njpb1s which claim to be reliable to 248 deg F, but as I said, I have found them to be a problem at much lower temperatures while riding. Though they seem to perform better than many of the nylocks I have used that came with the racks, etc...