All images by Bruno of Kupau Tours, Hawai’i, unless otherwise stated. Click on any image to view full screen and then use your back button to return to the text. Thank you Bruno for the awesome pics.
Sunset wasn’t much more than an hour away. I was hunched over my bike, resting my forehead on my handlebars. My heart rate was maxed and I was taking breaths in great gasps. I’d been riding up this single climb for over nine hours already, but the summit was still 4km away, within sight, but 600m above me. I wasn’t sure that I could make it.
My hands were going numb, starting with my thumbs and then moving inwards, finger by finger, as I gained altitude. I was yawning repeatedly and my legs moved woodenly. As Bruno, my guide had correctly predicted, things had become tricky around the 3,500m mark and my body was simply telling me, in multiple ways, that it wasn’t getting enough oxygen.
I rode another 50m and then stopped again. I walked the next 100m and then tried riding again, but the road was locked at 15 – 20% and I didn’t get very far before I needed to stop again. It had been a very long day and my self-inflicted torture wasn’t over yet.
I’d booked this trip some ten months earlier, in search of an idyllic family holiday, where Tom (my 18 yr old son) and I could also ride our bikes. Pete Stuart’s article in Cyclist magazine entitled ‘Mauna Kea: The World’s Hardest Climb’ had also been something of a catalyst, confirming that we’d have a genuine challenge to tackle: https://www.cyclist.co.uk/in-depth/3962/the-worlds-hardest-climb-mauna-kea-hawaii
By the time we arrived on Hawai’i, aka The Big Island, we’d already sampled the neighbouring Maui, culminating with a successful but very wet and wild ascent of Haleakala (a 60km climb with 3,000m of continuous up). We felt acclimatised and ready. However, one of our key discoveries on Oahu and then Maui, was that Hawaii’s weather was extremely variable: the easterly Trade Winds were almost always blowing – sometimes very hard – and it rained a lot – and by that I mean A LOT! Add into this the occasional thunder storm and in Kea’s and Loa’s cases the risk of snow and ice and it was increasingly evident that finding a day when the conditions offered any chance of success wasn’t going to be easy.
There was a second, even more defining piece of news: as we flew into The Big Island, the access road to Mauna Kea’s summit was closed due to snow and ice. I prayed the sun would melt this problem away – quickly.
Pete Stuart had strongly advised that we’d need vehicular support for Mauna Kea. There was no access to water for long sections of the climb, plus we’d need a way of getting off the mountain quickly in the event of the onset of altitude sickness, or the arrival of an electrical storm. After a bit of searching, we’d found Bruno of Kupau Tours. Bruno got in touch on the Wednesday that we arrived and checked that we were still intending to attempt the climb on Friday, as originally planned? That prompted a detailed conversation about the weather: Friday’s forecast was for thunderstorms on Kea, which would be lethal on a bald mountain with absolutely no cover at all. A cyclist might as well pin a target on their back saying ‘strike here’! Saturday looked wet and windy, but Sunday looked good, so with amazing flexibility from Bruno, we settled on Sunday 30th December as ‘The Day’.
To really understand the nature of the challenge, you need to know something about the history of the Big Island. It’s the youngest island in the Hawaiian chain and is formed of five volcanoes. Some of these are dormant and others are active. The largest two – Mauna Kea and Mauna Loa – are simply huge. In basic terms, Kea forms the north of the island and Loa the south, with the Saddle Road bisecting the two and connecting the west and east coasts. Their peaks are above 40% of the atmosphere and 90% of its water vapour, meaning their summits are often clear, even though they appear shrouded in cloud when viewed from below. They’re large enough to have their own micro-climates, so the general forecast may be nothing like what’s happening on the mountain itself. Even more bizarrely, given they’re opposite each other and their summits are probably only 20km apart, they can be experiencing completely different weather at any given time. There could be a storm raging on one, while the other’s bathed in sunshine and an hour later, this could be completely reversed. Sure enough, the weather forecast that had ruled Kea out for Friday looked good for Loa, so Tom dialled in 290 watts for four hours to take the Strava KoM, riding right around a thunder storm in the process! https://www.strava.com/activities/2041239038
With this in the bag, he decided not to ride Kea – he’d done his research and didn’t fancy the prospect of loose gravel and walking – so I was on my own.
From my base at Hapuna on the north-west shore of the Big Island, Mauna Kea’s summit was 98.5km away and 4,207m above me. My route would take me from Hapuna Beach, eastwards across the island, via the Saddle Road – a remote mountain highway that crosses the 2,000m col between Mauna Kea and Mauna Loa.
After c.74km of varied but pretty much continuous climbing, I’d arrive at the foot of the Mauna Kea Access Road, where, laughably, the climb would get much harder. The Access Road is 24.5km long and can be broken down into three sections. The first 10km climbs 800m to a small Visitor Centre, via ever steepening slopes and long 12 – 15% ramps. By the end of this section, you’ll have ridden c.84km from the coast and will have climbed 2,800m from sea level.
At this point, the climb would get significantly worse! Ahead lay 7.5km of loose and seriously steep ‘gravel’, although I would later reclassify this as ‘sand and rocks at 10 – 20%’. Bizarrely, 7km short of the summit, the gravel ends and the tarmac recommences, but in long, ever steepening ramps. With 30 – 40% less oxygen than at sea level, these 10 – 20% slopes would form the very worst part of the climb.
I was confident I could make it to the Visitor Centre, but above that, nothing was certain.
I exchanged a final few notes with Bruno, (crucially, the summit road had been cleared of snow and ice and was open again), cleaned the chain on my OPEN U.P. and fitted my 40mm Clement (now Donnelly), gravel tyres. I went to bed on Saturday night nervous and slept badly.
7.00am, Sunday morning, 30th December: I was sitting outside the hotel lobby drinking coffee when Bruno arrived and introduced himself with a warm smile and a reassuringly firm handshake. “I feel good about today” he said. I asked him whether he’d ridden the climb himself? “Yes” he said “and I’ve run it as well.” I realised in a blink that my guide was a significantly better athlete than I was and felt a little stab of extra pressure not to let him down! He’d shuffled his plans to support me and I felt that I needed to respect that flexibility with a really strong effort to succeed.
Bruno checked my planned route and then asked me about my expected timing. I explained that I was conservatively thinking five hours to the Visitor Centre (84km and 2,800m) and then five hours from there to the summit (14.5km and 1,400m), plus an hour for stops. I was allowing 11 hours and besides, sunset was in 11 hours.
4,207m above me, Kea’s summit was crystal clear. Behind me, waves crashed onto the beach. I turned left out of the hotel onto the highway and made good progress to the Waikoloa junction. Turning left, I started the climb proper – and the prevailing easterly trade wind almost stopped me in my tracks. This had become interesting earlier than I’d expected. At 83kg, I’m a big guy, but even I was getting moved around and having to work way harder than I would have liked. Strava would later confirm that for the next six hours, I was working close to 100% intensity, destroying my hopes of conserving energy until the upper portion of the climb.
I’d agreed to see Bruno every 45mins or so, where I’d eat a little food and refill my bottle. I mentioned the wind at our first rendezvous and he simply smiled and said “this is all part of the challenge Guy.” Thankfully, the wind was never worse than on those early slopes and the upside was that I was kept cool, rather than melting in the near 100% humidity and 28 degree heat.

The Saddle Road, at 2,000m. In Europe, we’d call this a col, but we probably wouldn’t be riding through lava flows!
I only had three things showing on my Garmin screen: elevation, power and speed. I was trying to keep my watts between 180 – 230 and largely succeeded, but I was slower than hoped, meaning that I didn’t reach the Visitor Centre until just before 2.00pm, almost two hours behind schedule. I was averaging just 12km/h. I’d kept my stops short, so this was simply the impact of the headwind.
I took a quick break at the Visitor Centre and agreed the plan with Bruno – he’d stay behind me for the first few kms of gravel, until we saw how I was coping. I let my tyres down to 40psi and lowered my saddle by 5mm. Most people bring mountain bikes for this part of the climb: big fat tyres and super spinny gears. In contrast, I was on 40mm tyres and my lowest gear of 38×42 might or might not prove to be enough. Bruno had my trainers ready, in case I needed to walk.
I’ll let you into a secret: along with cobbles, gravel/off road is my favourite surface. Sure enough, I cleaned 6.5 out of the 7.5km of gravel, despite the fact that it’s basically sand, mixed with rocks, some of them well embedded and others loose, added to which, the constant 4×4 traffic has churned the surface into a never-ending series of shallow dishes, making forward progress even harder.
The clouds were now below me and the scenery was becoming epic, although I was concentrating so hard on finding the best line I barely noticed it. Some 4x4s slowed down and gave me shouts of encouragement, while others sped past, covering me in volcanic dust!
The final km of the gravel section was the worst and once I’d lost traction, there was no getting started again. The last gravel corner soared above me at c.20% and I knew I was going to have to walk. Bruno was on hand with my trainers and I trudged up the gravel, pushing my bike. Ever walked up the face of a sand dune? Now imagine doing that pushing your bike, with far less oxygen than you’re used to: that’s the final km of gravel on Mauna Kea.
What comes next is even worse. It shouldn’t be – the surface had turned back to asphalt – but it was truly awful. The gradient was locked into an average of 12% for the final 7.5km, although my Garmin never registered anything much under 15 – 20%. I can honestly say it was like attempting to climb the Mortirolo, or the Zoncolan, but at 4,000m. It was fundamentally hideous.
My breath came in gasps.
I’d ride for 100m and then stop. I’d changed back into my bike shoes, but quickly reverted to trainers. I could still pedal wearing these and it was clear that I was going to have to walk as much as I rode. My heart rate was maxed, my legs felt wooden and my hands were slowly going numb. I’d already added knee warmers, winter gloves, a hat, a warm jersey and a shell, so this wasn’t really a cold issue. It was an oxygen deficit issue and my heart was simply prioritising which bits of my body would be supplied with oxygen. Clearly my hands were expendable!
Generally, mind over matter works and I’m adept at chimp management, but this was no longer a head game. Yes, I could force myself to keep moving forwards and upwards – and I did – but this was now primarily a physical challenge and altitude was slowly beating me, no question at all. I was acutely aware that at some point, altitude would win.
I was yawning uncontrollably – again, my body’s way of telling me that it simply didn’t have enough oxygen for what I asking it to do.
The question was, could I reach the summit before either altitude or darkness shut me down. I voiced this concern to Bruno at our final stop and he smiled and said “you’ll make it Guy and besides, my car has headlights to light your way if necessary”.
There was one positive to the self-imposed torture that I was now undergoing: I’d gone through the gravel section much faster than expected and therefore, it was only 4.00pm. My Garmin seemed to have stopped recording distance, but the altitude data looked spot on. Bruno told me that I could all but see the summit and that gave me added encouragement. Surely I could make this?
My hands were now useless, I felt slightly wobbly and my speech was slurred, but I was damned if I was going to stop. I’d keep going upwards for as long as I possibly could.
Somehow, at 5.30pm, I rode onto the very summit of Mauna Kea. Bruno was there and took my bike from me. The summit was busy with people who had driven up to watch the sunset and someone came up to me and asked if I’d ridden all the way from the Visitor Centre? I simply said “no, from sea level” and he looked at me in slightly stunned silence.
We lingered briefly, watching the sun turn the entire sky to fire. The cinder cones of the summit turned red and the sun reflected off the clouds, far below.
I’d summited in 10hrs 30mins, with little more than 30 minutes of stoppage time.
So, is this the world’s hardest cycling climb? I’ll be quick to believe anyone who says it is. It’s the hardest climb I’ve ever come across, by a fair margin.
I owe thanks beyond words to Bruno of Kupau Tours. His knowledge, support and positivity were outstanding and despite the severity of the challenge, I felt I was in very safe and professional hands, which allowed me to focus on simply riding my bike. Thank you for helping me to realise a dream.
As ever, I also owe thanks to those who helped me reach this particular summit – ASSOS LDN and ASSOS of Switzerland for creating clothing capable of tackling a challenge like this and Bespoke Cycles for preparing my OPEN and Tom’s Mosaic for these particular adventures.
Aloha from Hawai’i and Mahalo Bruno for your help!
SGL, Dec 2018.
Tips/Observations:
- Most ascents are made from Hilo, rather than from the Hapuna/Waikoloa side of the island. The Hilo route is shorter (70km). You’re more likely to get a tail wind from Hilo, but you’re also more likely to get wet from that side of the island (it rains a lot in Hilo). I asked Bruno where he thought it was best to start from and he said Hilo (I was already a long way up the mountain when I asked him this ;-).
- In my humble opinion, don’t ever attempt this without a support vehicle. Descending the gravel would be nigh on impossible (it’s sand remember) and there is a fairly good chance you may need a rapid extraction, whether due to altitude sickness, or a sudden change in the weather. Having a support car gave me the confidence to push on, even when things were beginning to get marginal. I wouldn’t have made it to the summit with that safety net.
- Use a mountain bike above the Visitor Centre, with big, fat, knobbly tyres. Take the smallest gears you can possibly find. I was under-tyred and over-geared.
- Be very flexible on your exact ride date and arrive on the Big Island with as wide a window of options as possible: I was there for five days and only one was workable. We had similar problems with Haleakala (rain) and Mauna Loa (lightning).
- I think climbing Haleakala and Mauna Loa before Kea helped: not enough to acclimatise to the altitude, but they’re long climbs and somehow, I think they’re additive preparation. Both would be outrageous climbs anywhere else, but compared to Kea, they almost felt easy!
- Make sure you have access to plenty of warm clothing from the Visitor Centre onwards.
- Almost all of my route prior to the Access Road had good, wide shoulders, so even though they’re pretty significant roads, they felt pretty safe (to me, at least). The shoulders are covered in small stones and broken glass though, so if you run road tyres, make sure they’re tough ones! The Access Road doesn’t have a shoulder, but is pretty quiet and I felt very safe on it. I used blinker lights until the Access Road and wore visible colours.
- Start early – 7.00am ish. I felt that I was racing sundown. Keep your stops to a minimum. I took four five minute breaks and lost a few more minutes changing shoes and trying to breathe!