Hi there, first time poster, getting ready to do a one-day ascent on the main trail in September.

I'm putting together an itinerary that I can use so our group makes sure to not go too fast or forget to eat and drink. Having not hiked at altitude before, but being a strong hiker at lower altitudes, does anyone have any thoughts on how altitude affects pace?

I hiked Mt St Helena in the SF Bay Area, 10 miles R/T, 2000 ft elevation gain last week with no problems at a 17min/mi pace.