I would say the gps on your phone is way over stating the elevation gain. It's certainly possible to get 5100 ft of climbing in 35 miles but you'd have to be somewhere like the Sierra's to do that. Rides that have 10,000ft of climbing in 100 miles are considered extremely difficult. I know of only one ride where there is approximately 10,000ft of climbing in a 70mile section of it and it climbs straight from nearly sea level to almost 10,000ft.