Hilo to Mauna Kea

I remember seeing on Strava that Justin Rossi rode up Mauna Kea last winter and took the KOM. Not a big surprise as he’s super strong. At the time though I didn’t know just how hard this climb was. Justin and an astronomer friend who has worked up on Mauna Kea filled me in on just how hard the gravel stretch was.


The gravel STARTS at 9,300′ above sea level.  It is 4.6 miles long and AVERAGES 10%.  The biggest problem is that it is really coarse and loose volcanic soil.  Traction can be an issue, especially when it pitches up above 10% where standing up will just allow the rear wheel to spin.  You really need to do this in the saddle.  Another issue is that it can get really loose.  My 25mm tires sunk in numerous times.  The catch is that when you’re going 6 mph on a 10+ percent grade and your front wheel sinks in it is almost impossible to recover and you grind to a stop.  Then, how do you get going again in those conditions.  In my case, a lot of times I had to walk until I found some harder packed sections or the grade eased up.

Besides that the paved sections once you get to the mountain proper are pretty brutal in their own right.

When my wife and I started planning a Kona cycling vacation with some friends I knew that I would have to take a crack at it. I quickly gathered that my normal 52×36 and 11×28 would not cut it. I hoped that by going with a 34 tooth small ring and an 11×32 cassette I’d be able to ride more of the gravel section. Hahahahahaha!

I came to Kona expecting to do this alone. I brought a camel back and all the warm clothes I’d need for the descent along with some chemical heat packs for my hands and feet. Watching the weather I decided that Friday the 12th was the day. As it turns out though our whole group worked together on the logistics. Steve and I drove to Hilo, parked the car and stashed the keys. Harlan, Liz, Kitty and Jody drove to the junction of Mauna Kea, Mauna Loa on the saddle road and Liz, Kitty and Jody rode up Mauna Loa and then back down to Hilo to pick up the car. Rob was going to ride from our rental house in Kona to Mauna Loa and back but was thwarted by a brush fire that closed his route. Harlan after dropping our wives off met Steve and I at the junction to drive support. He felt like he needed a rest day and I will be forever grateful for his help. BTW, Steve’s plan was to ride to the Visitor’s Center at 9,000’ and then back to Kona. He couldn’t help himself though and descended from our house (at close to 1,000’ elevation) down to the Kona pier for a “coast to coast” ride. He was sad though to find out that everybody was still on the other side of the island when he got down there and had to climb back up instead of hitching a ride. 🙂

I came here wanting to take the KOM, but frankly wasn’t even 100% sure that I’d make it to the top with the gravel. After a fair amount of poring through Strava files and segment data I decided to try and ride to the top of the saddle road shooting to average between 280 and 290 watts. I use Strava live segments on my Garmin 520, but decided not to look at whether I was ahead or behind until I got onto the saddle road proper a bit over 25 minutes in. When I looked we were about 2.5’ ahead of KOM pace, but then my Garmin went stupid and said that I was off course and would have to rely on a few splits that I remembered. It’s a long way to the top of the saddle road and I was feeling the effect of my efforts as we approached the two hour mark nearing the junction. Nonetheless I was able to take a selfie on the fly of Steve and I on a flatter section up at around 6,000’. (BTW, did I mention the nice tailwind we had?)


Shortly after this picture was taken Steve flatted and being the good friend that I am, left him to fix it himself. 🙂 Seriously though, he told me to go on and I did.

I got to the junction of Mauna Kea in around 2:04:30 and was still ahead of schedule but definitely starting to feel the efforts. Motoring along on a steady 5% grade is something I like and am fairly good at, but the serious shit was about to start and I went into “don’t push it mode”. When I turned right towards the mountain I could feel that tailwind I’d had as a cross wind and knew that I’d pay for that later on some of the long switchbacks that point towards Hilo. Luckily though it was a fairly light wind and didn’t cause too much grief.

I remembered that there is a segment on Strava called “Steepest Mile of Mauna Kea” heading up to the Visitor’s Center. It starts at 8,000’ and averages 13% with sections at 18%. It was unpleasant, but I made good use of my 34×32 and made it through. The road turns to gravel right after the Visitor Center.


This is where I hoped that my 34×32 would really help me and allow me to stay in the saddle to keep traction on the dirt to minimize or even maybe avoid having to walk. HA! I made it less than 50 yards before my front tire sunk in and ground me to a halt. Not a good start at all. I remounted quickly and keyed in on looking for the solid portions that you could see and avoid what was obviously just packed gravel. If it was just a dirt road, it would be hard, but probably 100% rideable with my gearing.

Long story short, the gravel stretch took me 1:11:33 to ride 7.4 km, for a blistering average speed of 6.3kph. I dug into my ride file and counted a total of 35:10 where I was not pedaling. I’m stubborn though and just kept moving knowing that many others had done the same. The only time I stopped moving was when my phone for some reason started playing from my Amazon Prime music app while I was walking. I stopped, dealt with that and decided to take a quick potty break. I didn’t need to, but at that point I figured that the KOM was gone so…

This pretty much sums up the gravel stretch.


Thankfully the gravel finally ended. But at that point you’re at 11,400’ and there are some very unpleasant stretches before the top! At this point I was almost exclusively in the 34×32 and due to the steepness and the altitude I was “doing the paper boy” most of the way, weaving back and forth across the road to minimize the grade. Even doing the paper boy though I made up a ton of time on that stretch and only missed the segment KOM by 29 seconds. I know that Justin Rossi had a 39×32 when he did it and I’m pretty sure I would not have made it to the top in that gear.

This chart is interesting and pretty much sums up my experience.


I was trying to do the math in my head. At 4 km to go I was averaging around 6 kph (SIX!!) which means 10’ per km, so 40 minutes to the top more or less. I had a shot. I’d like to say I made a heroic effort and dug deep, but the reality is that I just slogged along as well as I could. When I finished I thought I had missed the KOM by 20-30 seconds and was regretting the pee stop. Thankfully Strava is better at math than I am and I got the KOM by 38 seconds.

I think I got really lucky with the weather. Not only did I have favorable and light winds, but it was fairly pleasant up top. I was quite comfortable in shorts and short sleeves all the way up. After pictures and a bit of sight seeing I bundled up and descended down to the start of the gravel where Harlan picked me up and we drove back to Kona. I rode just a tiny bit of the gravel descent to see how it would be if I did the ride unsupported. My conclusion is that it would probably take almost as long to descend the gravel as it did to climb.

Here is a link to the pictures I took.



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