Red Lodge, MT, to Billings, MT

[GTS_Rider]

No, elevation is measured above "sea level", altitude is your height above land. So for example, if I climbed a mountain and was standing on it at 10k feet, my elevation would 10,000 feet. If I was flying 10 feet over that mountain, my altitude would be 10 feet. At least that's my understanding of both, correct me if I'm wrong.

So, you're saying that if an aircraft is flying along at 30,000 feet altitude, then flies over a 20,000 foot mountain, the 'altimeter' will go from 30k to 10k when they fly over the mountain?

P.S.

Sorry to the OP for the thread-jack, but every time it pops to the top, more likely someone would know the best route. Otherwise, I can't even imagine peddle biking up that road. I was short of breath for the little walk to the lookout point at the top...

 

[UHOH]

A bit of background.  Trip begins in Florence, OR, then over to Eugene, then over McKenzie Pass, then up through Utah,
cross Lolo Pass, and into Missoula.  From Missoula down to Yellowstone.  ... But like I said above, open to other options.

To activate an older thread - lot of zigzag, but what do I know?   What's with Utah - on your route?

Me, I'd go from Boise east via US 20 to Idaho Falls, then Jackson, WY and maybe Yellowstone if you're set on it.  
Would seem a more gradual ascent to the high park, with alternate eastward options that seem more cycling friendly.
 But my longest cycling trip has been 3 days - so I fully don't understand.

anyway you go, bet you'll enjoy the heck out of it...