LOL, is that the only photo you have of that flask? Yeah, I'd post it too if I'd climbed that. I'm surprised you don't put this photo in every thread.I use a Thermos Ultimate 800ml in a Monkii cage.
My wife sometimes takes a 500ml flask in a standard cage using the cut off bottom of an old water bottle to stop it moving.
All thermos flasks insulation is not metal (or glass) it's the layer of air+nothing, hence vacuum flask. Heat is lost through radiation, conduction, convection and evaporation. Your worry about the bike frame is that heat will be lost through conduction. But the metal that touches the hot liquid does not touch the outside. Here's a nice diagram.
Well, they all would be warmer on the outside than they would be if they didn't didn't have have warm liquid inside them, but I've got flasks that don't feel noticeably warm to the touch - I'd need two identical flasks side by side to tell it was warmer than is should be. A flask that feels warm to the touch usually contains a liquid best described as tepid.
That scientific stuff is all well and good; but I remember when I bought my first flask. The person in the shop told me it would keep hot things hot, and cold things cold. Well mine didn't quite work as expected when I went off to work the next day. Imagine my disappointment when I opened the flask and discovered that after just a few hours my chicken soup was no longer hot, and my rum and raisin choc-ice had meltedAll thermos flasks insulation is not metal (or glass) it's the layer of air+nothing, hence vacuum flask. Heat is lost through radiation, conduction, convection and evaporation. Your worry about the bike frame is that heat will be lost through conduction. But the metal that touches the hot liquid does not touch the outside. Here's a nice diagram.
If a flask gets warm on the outside, the metal contact will help it lose heat more quickly. But a flask that gets warm on the outside, has pretty well failed as a flask, and will lose heat quickly by radiation.
@Distorted Vision , I'll put my flask outside in the mild November weather for a couple of hours if you like, and let you know how hot it stays. I know when I use it at a coffee shop, and they say "we put extra hot milk in there" it's still too hot to drink an hour later.
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Typical Scot - too mean to buy two flasks
A true Scot would have one of theseTypical Scot - too mean to buy two flasks
I've got one of these http://www.kathmandu.co.uk/accessor...ion/vacuum-carabineer-bottle-dark-blue-1.html
paid a lot more for it. I use the carabina to clip it onto a bag, but it fits loosely in the bottle cage. A sock around it would stop it rattling.
I like it because under the waterproof lid, it's a travel mug, so you can just drink the contents through the small hole in the lid.
