If you're talking about a steep hill that is five miles long, I've never tried that. The steep hills around here tend to be shorter so you're able to recover before you reach the next one.

But fwiw, I find that I have to shift into the lowest gear and slow my cadence down, sometimes as low as 50 rpm with a speed of only 3 mph. But that's what allows me to reach the top with minimal (or no) wheezing.

If I know a hill is likely to cause a problem, I will use the rescue inhaler (1 puff) before I start the climb.