Every year it’s the same damn thing
The forecast high yesterday was 35C, so I knew I couldn’t go on a full-fledged ride. Ten years ago I could ride in 35C weather and everything was fine so long as I didn’t push myself too hard, and I made sure I drank enough water. But starting two years ago, on a hot, sunny day, I experienced very sudden and very severe bonk. On that first occasion, it was all I could do to roll downhill and tumble off the bike into the shade of a friendly tree. After resting more than 10 minutes and drinking a lot of water, I ate a couple of onigiri and then I could continue. It was only after the ride that it occurred to me this wasn’t the bonk — it was my body refusing to push on in the heat.
I experienced the same thing again last year at similar temperatures and again on a sunny day. The same sudden loss of power, and a slow, partial recovery after a break in the shade with lots of cold water and something to eat.
Each time I told myself I’d learned a lesson: Don’t ride when the temperature is higher than, oh, perhaps 32C. And each summer I tell myself, “It will be OK this time. I’ll set out early and I’ll get home before the heat really comes on.” And then I set myself a schedule which makes that impossible.
And yesterday was another case in point: I figured if I left by 8 a.m. and only went as far as Haneda, I could be home before noon. And then for some reason I figured if I could ride to Haneda, I could ride to Yokohama. It’s not all that much farther to go, the view from Minato-no-Mieru-Oka Koen is great, and I hadn’t been there in a while. The Halfakid agreed to join me and so the schedule was set.
It’s already near the limit
When I set out from home yesterday morning at 8:10, my phone told me it was already 31C. Hmm … that’s about my limit, right? Maybe I should change plans and just go to Haneda. But I put the Yokohama route on the GPS (I don’t really need the navigation — I know this route) and set off to meet up with the Halfakid. He was waiting for me, all ready to go except for pumping up his tires a bit. My tires also were in need of air, even though I’d filled them just an hour before starting the ride. (See the Weeping Sidewalls.) So we were getting even more exercise than we’d bargained for as we pumped our tires up. At least we were standing in the shade!
Cruising down the Tamagawa
Soon we were cruising down the Tamagawa cycling course with a tailwind to help us along. The sun was very strong and I was thinking I should have worn my UV mask (which I’ve been going without this year, for no particularly good reason). The temperature was rising steadily, but we didn’t feel bad so long as we were moving. The path was crowded and the Halfakid fell slightly behind at times as we wove in and out between other cyclists and joggers. We continued on until we came to our usual rest spot in the shade.
Asphalt canyon
Once again I considered whether I should change our plans and only go as far as Haneda. I was starting to feel fatigue from the heat, but nothing extreme yet. We mounted up and continued along, making good time, and were soon crossing the bridge over the Tamagawa into Kawasaki. From here we continue on Route 15 nearly all the way to our goal, about 16km on. It’s a straight shot, but it’s all in traffic and it’s a veritable asphalt canyon. There’s no hiding from the sun and the temperature soars. We found ourselves stopping scores of meters back from the traffic lights if we could rest in the shade while we waited.
At a small park about 5km after the bridge we stopped for an onigiri and some water as we sat in the shade. I felt recharged. Then it was back into the asphalt canyon. The road is straight and flat, and so the heat was our only real opponent (and the occasional driver who ignored our hand signals as we maneuvered around parked cars and other obstacles). We rolled through Yokohama and passed the entrance to Chinatown before stopping at a convenience store to supplement our onigiri lunch.
While the Halfakid shopped for cold water and coffee, I leaned against a railing in the shade. I knew the heat was getting me — it was 34C at this point. I’d have preferred sitting down but there wasn’t really any place for that. I just had to wait, and when the Halfakid emerged with some cold bottled water I accepted it gratefully. I drank perhaps 300ml or more despite knowing we’d soon be climbing our way up to our goal in the park.
I’ll beat that climb someday
The final 300m to Minato-no-Mieru-Oka Koen is a rise of 29m, just shy of a 10% average. The steepest bit is 13%. It’s not the world’s longest climb, but it is on a twisty road with fast traffic, so I can’t zigzag my way up. And it comes at the end of a 40km ride just to get to the start. Anyway, long story short, I have yet to reach the top in a single go. (No such worries for the Halfakid, who just rockets past me before waiting at the top.) I usually get about halfway up before giving up just after the steepest bit. This time, with the heat sapping my power, I gave up a good 15m before my usual spot. And from there it was all I could do to push Kuroko the rest of the way up the hill. I really just wanted to stop where I was and have a rest, on the narrow sidewalk with no shade.

View from the top
The reason we stop at this particular park (apart from things like restrooms, a water fountain and park benches) is the view over Yokohama Bay that the brief climb affords us. We were lucky in that I quickly found an available bench (there aren’t many), and we sat in the shade and quickly finished the remaining onigiri.

The difference between theory and practice
As we ate and rested, we joked about how quickly we could get back home. After all, it’s just about 40km and we were averaging better than 20km/h despite my stroll up the final climb. In reality, we’d taken three-and-a-half hours to reach the park even though we’d been riding just about two hours by this point. The difference reflected both the long breaks we’d been taking and the stop-and-go traffic we’d had along Route 15 and through Yokohama. I’d told Nana before leaving home that I’d be back around 3, and I realized that this was now unlikely.
Smoother sailing, at least at first
We set off home, flying down the hill from the park, and found our way back out of Yokohama much smoother going than coming in. We were hitting far fewer red lights. But we were soon back on the asphalt canyon of Route 15. My speed was still a hair over 20km/h, but I was wondering how long I could keep that up. We agreed we’d stop for rest and refreshments when we crossed the bridge back in Tokyo, but I was starting to feel I wouldn’t make it. The only thing that kept me going was the lack of shady parks along the route. (I suspected I could quickly find more than a few just a block or two off the main road, but I was playing a mind game with myself to keep going.) I felt quite weak but I was still keeping pretty good speed so long as the road was flat and straight and I wasn’t fighting a headwind.
We came at last to the bridge without incident. We usually ride up the pedestrian ramp to the bridge — it’s very gentle — but there was another cyclist coming down it as we approached, and I didn’t trust myself not to wobble into him in my current state. So we dismounted and pushed our bikes up the ramp. I knew I was taking my time up the ramp but I didn’t realize how slowly I was going until another cyclist passed by me while pushing his bike up at a much faster pace.
Ice cream!
The bridge is nice and flat, and we dawdled across it. At the far (Tokyo) end, there’s a spiral ramp down to street level which lands us nearly at the door of the convenience store. I sat down on the asphalt pavement in the shade by the bicycle stand and worked at an ice cream sandwich and a lot of cold, cold water. I had a good long rest here, and updated Nana on our status.
Back on the Tamagawa cycling course, my mantra was to just keep moving and not to worry about my average speed. (OK, I did keep stealing glances at the GPS and fretting that I’d fallen below 20km/h, but I didn’t try to get the speed back up.) A scant 4km after the convenience store, we arrived back at the site of our first rest stop of the day, and I pulled in for a brief stop. More water and a few precious minutes in the shade. The Halfakid and I discussed whether it would be easier to go on the road, in traffic, than on the bike path. The bike path would give us a couple of switchbacks to climb — the one at Marukobashi is rather substantial. The road is fast and smooth, by contrast, but there’s a tunnel a few hundred meters long just before coming into Futako. There are probably ways around the tunnel, but I wasn’t feeling adventurous. We continued on the path.
And when we came to a shaded rest area another 4km further on, I stopped again. I had enough water left to get me to Futako, and we discussed whether to buy more water before the climb at Futako or after. The Halfakid said he was fine for water, so I decided to stop at a convenience store or vending machine at the foot of the climb. I’d need to carry the water up the climb, but I’d have it right when I needed it at the top. We set off again for the final 4km drag to Futako, and again I just concentrated on keeping moving rather than looking at my speed. I’d switched down to my smaller chainring at this point, usually only used for climbing, and I just stayed on it. I could get up to just over 20km/h (given a tailwind) without having to move to the larger chainring, so I stayed with it.
The dreaded climb
Of course we eventually reached Futagobashi and crossed the Tamagawa for the final time into Futako. At the foot of the climb I told the Halfakid to go ahead while I stopped at a vending machine. I drank some of the water on the spot and then poured the rest into my water bottle. And with that I was off up the climb (much gentler than the one in Yokohama at a 4% average). I just dropped to my lowest gear as soon as possible and took my time up the hill.

While we rested at the top of the hill, I checked the time and made some mental calculations. The Halfakid was still fine — he’d charged right on up the hill. I was feeling somewhat better. The temperature had probably started to fall, and even though I was in the city now there was more shade. I messaged Nana that I would probably be home between 4 and 4:15, and we set out on the last leg. It’s only 5km (in traffic) to the Halfakid’s flat, and we soon reached it. After a fist bump he carried his bike in through the door and I sat down on the step for a couple more minutes of rest before continuing.
The final 8km home went well (apart from a few idiot drivers, as usual). I modified my course slightly at the end, swapping a straight, fast-moving and heavily trafficked road with a bit of climbing for a back road with some pedestrian traffic and numerous cross streets. This route takes me right by the train station, but I was resting in shade while waiting for the traffic light. At last I reached Chuo Koen and the final downhill to home. I usually crank up the speed here to see how fast I can get it (depending on traffic), but this time I was content just to coast down the hill. I got enough speed even so (32km/h) that I hardly had to pedal to reach the goal. I stopped the clock at 4:08 p.m., within the time that I’d told Nana.
You could even say it glows
After having a shower, I noticed in the mirror that my nose was bright red. I’d used SPF70 sun cream, but I really ought to be wearing the UV mask (or just not biking) in this sort of weather. Nana was calling me “Rudolph.”
While my symptoms during the ride fall well short of heat exhaustion, I still think that I shouldn’t ride under these conditions. I’ll need to either stick to my resolution to leave early and return early, or simply not ride when the forecast is saying it’s a bad idea.
Apart from the weeping sidewalls of my lightweight tires, mechanicals were minor. The disc brakes squealed very faintly on a couple of occasions. I’ve ordered resin brake pads to replace the metallic ones I’m using, and that should take care of it. I also had a return of the problem with the front shift lever, but I know now how to deal with that on the fly. It’s an annoyance, and one I’m considering a couple of alternatives to fix.
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