All the cycling data and info you'll need to climb Haleakala Gravel

The first 5 miles of this extraordinary climb are paved and on Waipoli Road at 10.2%.  The remaining 13 miles are gravel averaging 5.6% (8% climb only).  Turn left onto Skyline Trail at mile 11 and ride that trail the final 7 miles to the Haleakala Summit Building.

Climb summary by BY Ray Gurzynski

From the start of the Waipoli climb to Haleakala Summit is the #2 most difficult climb in the U.S. (33.8 miles / 10,021' / 5.9% average grade / Fiets 18.68; we did not rank it because it is impassable on a road bike)​.  From Waipoli Road at about mile 13 to Haleakala Summit is roughly 18.2 miles / 7,185' / 8.9% / Fiets 17.12 - that alone would be #6 U.S.  This is not manageable on a road bike, so we do not include it on our list, but at 18.68 Fiets it ranks #2 U.S. and #6 World - https://ridewithgps.com/routes/21799781 
PJAMM Strava Buddy, Ray Gurzynski, writes of this spectacular adventure:

This route is similar to Mauna Kea in the sense that the hardest part is an unpaved upper section which finally blessedly reverts to pavement near the top. Also like Mauna Kea, the unpaved section varies from challenging to marginally ridable to it's walk-a-bike time.
I have not ridden MK but have been up there in a vehicle so I feel qualified to make this comparison.
One difference perhaps is that the MK section is periodically graded, which creates a substantial variable in the difficulty equation. While it would never be "easy", if a rider had the good fortune to ride MK right after a grading it might be slightly less terrible, that being as kind a description as I'd use for that beastly stretch!

The Skyline Ridge Trail on Haleakala is a typical doubletrack jeep/4x4/logging/fire road. (regional terminology varies but they're all about the same- I'm sure you get the idea.).  The upper portion of the SRT was the worst. My impression was that it has been graded in the past, but not anytime recently. it was very chunky- thick lava landscape rocks from golf to baseball sized for the full width. This stuff was simply unrideable in a few places. In fact, it was difficult to walk in, let alone push my bike, and I was wearing nice wide soled Teva sandals. (sort of a trademark of mine- I like getting off my bike and walking like a human, rather than hobbling about like an injured bird.)

But I digress...

The Waipoli unpaved section obviously is very heavily traveled, thus they have to keep it at least drivable. The SRT  gets essentially no traffic save for hikers, some downhill mountain bikers, and very occasionally someone like me doing it uphill. There's a mere handful of us on Strava. And I suppose official personnel periodically check on it's condition, but seemingly very very infrequently. Then thankfully there is pavement again near the top, access roads to the observatory stuff and the connector road over to the main tourist summit building.

Gravel section on the way up    

Finish