At our shop in New Mexico in the 70s, we used to use Pennzoil or Quaker State HD wheel bearing grease for repacking bike bearings. The reason was that besides being cheap, it was viscous (also called fiber grease) and wasn't affected by high temperature. Phil grease and other lighter kinds of grease, even Campagnolo grease tended to run out of the bearings in high ambient heat, especially headsets making a greasy mess.
It wasn't so much the ambient temperature but when a bike sat in the sun things would get messy.
As others have said, tires, rubber parts, leather saddles, tape and so on can be affected by heat. The heat in New Mexico, Arizona and parts of Tejas is a "dry heat" and it dries out things like leather, rubber and plastic. Whereas in other parts of Texas such as Houston it can be very humid which can result in faster than normal corrosion.
Chas. Colerich Oakland, CA USA
Baird Webel wrote:
> I am leaving an old Serrota at my parents' house in Texas so I don't
> have to haul a bike when I visit. My father suggested storing it in
> an attic above the garage. Outside temps in the summer would average
> mid-90s, so I'd assume an un-air conditioned attic would be
> significantly more than that for probably 3+ months of the year. I
> can't come up with a particular reason to give not to leave the bike
> there, but just have a vague sense of unease about it.
>
> Anybody have trouble from such a thing it the past, or am I just being paranoid?
>
> thanks,
>
> Baird