Aluminum and the cold
 

I am starting to shop for my next bike and it is more then likely going to be a nice aluminum frame with a carbon fiber frame. Since I live in Reno (right next to Tahoe), it gets really cold here in the winter (it snows quite a bit) and gets blazing hot in the summer.

Should I be worried about premature cracks in either my frame or fork because of the cold? If I'm riding in the morning towards near-freezing temps, should I be worried about medium length distances (12-16 miles)?

no

+1 regarding alu, no experience on carbon though.

Carbon explodes if you touch it. Everyone knows that.

Seriously though. No on both counts. They use carbon to make plane wings (or some bits of plane wings or tails anyway), and it's a damn site colder up in the air, and aluminum to make the planes.

My Scandium (AL)/carbon mix gets ridden all winter. No worries. My AL hardtail gets ridden and beaten pretty hard all winter. No worries.

People regularly do worse things in even harsher climates. Your worry is utter fallacy.

So, which is it, aluminum or carbon fiber?
Either way, you should avoid zero degrees Kelvin or Blazing Hot with Flames.

I meant "carbon fiber fork".

All right. Well thanks for putting my little head at ease ^_^

Quoted for truth. If the temperature is acceptable for human life, it's just fine for your bike.

I ride my bike in to the negatives (Fahrenheit) and really, it has never been a problem.