I purchased Kuroko with the goal of having a bike that wasn’t necessarily the fastest performer, but that would be comfortable for many hours in the saddle, day after day. In particular I had Lejog in mind, anticipating I’d be on the road for 13 or 14 straight days with at most one rest day.
Kuroko was a part of what was at the time an emerging trend: gravel bikes. While in my callow youth I sought out the narrowest possible tires (23mm), run at high pressure for efficiency and damn the comfort, Kuroko was equipped with the opposite: 48mm tires, run at 50psi at most and preferrably lower. When I researched this new trend, I was assured that the wider tires were both more efficient (although I’m sceptical about this) and more comfortable, and that the larger volume would reduce or eliminate the dreaded pinch flat (when the wheel strikes an abrupt edge, pinching the tube against the rim and causing a flat), which in fact Fearless Leader Joe experienced on Day 2 of Lejog.
These new tires also featured a new technology. They were tubeless, or at least tubeless-ready (meaning they could be set up as tubeless if one so desired). Instead of a tube, the tires are mounted directly on the rim, and a small measure of liquid latex is added (usually 60-120ml). The latex will gather around any leak or small puncture and harden, creating a seal.
I was excited about this new technology, and when I ordered the bicycle I requested that it be set up as tubeless. A day or two after I placed the order, though, I got a call from a rather direct-speaking Japanese (he was a mechanic and not a salesperson). He spent 10 minutes or so telling me what an inconvenience a tubeless tire was going to be for me, running through the full list of shortcomings of the new technology. While he didn’t right out say he wouldn’t set the bike up that way (he was Japanese, after all), the message was clear. And so Kuroko was delivered with standard bicycle innertubes inside her tubeless-ready tires. (I’ve since learned that particular shop is “allergic to tubeless” — they won’t even sell accessories related to tubeless tires such as rim tape and latex.)
And that’s how she rode through the breadth of England during our Lejog ride. I suffered two flats along the way and either swapped out the tube or patched it on the spot. (I’d brought along a spare tire — they’re foldable — but it wasn’t required.) By all indications, both punctures would have been no problem with a tubeless tire: pull out the offending nail and let the latex do its work.
I’d had it in mind since then to convert Kuroko to tubeless. I’d done quite a bit of bicycle mechanical work in the meantime, so this should be a walk in the park. I had a number of excellent videos to follow as well, and they all made it seem quite easy.
I bought the latex and the rim tape, as well as a tire pump with a compression chamber to allow me to inflate the tire in a single big burst. Thus equipped, I gave it a go and … no go. The tire wouldn’t seal to the rim. I tried it again. And again. And again and … I didn’t keep count but I’m sure on that first go I tried more than 20 times before giving up.
In the meantime, I’d been busy rehabilitating Ol’ Paint. And when that project finally came to fruition and I put the newly rechristened Dionysus on the scale, she came in at a very surprising 9kg! This was all serendipity, as I hadn’t specifically been working to make a lightweight bike. The wheels I’d built up, though, while not being tubeless, were quite light without being particularly expensive.
I contrasted that 9kg weight with the measurement I’d made when preparing Kuroko for Lejog: a hefty 13kg. Granted, at the time Kuroko had been decked out with a rear rack, pump, a generator hub on front, etc. I decided to strip Kuroko down to the essentials — no lights, no bags, no pump — to make a fair comparison. The result was 11.2kg (as you can see above).
I think we can do better than that!
I had no doubt that most of the weight difference was in the wheels (although Dionysus is a 1x, and so has some advantage in terms of fewer parts, such as lacking a front derailleur and having only one chainring). So I set out to get the lightest possible tires without sacrificing on the comfort or performance. (Kuroko’s existing tires were very comfortable and very smooth-rolling.) I quickly hit upon René Herse’s Babyshoe Pass tires: 42mm wide and quite a bit lighter (and rather more expensive) than the WTB Horizon tires I’d been using. I placed my order and watched for the delivery with salivary glands fully activated.
When the new tires arrived the first thing I did was to get them on the scale to compare with the WTB Horizon. I also weighed an innertube as this wouldn’t be included with the new tire. So I was looking at a weight savings of 390g per wheel? Perhaps not quite, as the tubeless tire requires a separate valve as well as somewhere around 100g of liquid latex. But that could still add up to a half kilogram of weight savings for the two tires.
There must be some sort of trick
With the new tires in hand, I took advantage of a visit by the Halfakid to attempt the installation. After all, I needed someone to pump up the tires. And again. And again … We tried several times, and used both of Calvin Jones’s recommended techniques, but we were no closer to having our beautiful tubeless tires installed. I was starting to think that all those videos I’d seen where the tires pop into place with no effort — particularly the dream builds where they just use a standard hand pump — were mocking me.
39th time is a charm
Today I was “working from home” and had nice weather, as well as a ride in prospect for tomorrow, so I decided to give it another go. I spent some time with the preparation: I removed the tire and tube, as well as the rim tape, and then cleaned the rim with brake cleaner, making sure to get any residual latex from previous attempts out of the bead area where the new tire would seal. Then I put the wheel on the truing stand for a quick check. In the case of the front wheel, no truing was required. For the rear, though, I’d replaced all the drive-side spokes following the big chain disaster of Stafford, and at the time I didn’t have a truing stand so I just trued the wheel up in the bike frame. As a result I found that while it was fairly round, it was off-center by more than 1mm. It took less than 10 minutes to sort that out, though.
With the wheels clean and true, I installed new rim tape, this time using 21mm tape from DT Swiss. (I’ve tried tape in the past from several makers and in several widths.) I spent a few minutes working out any bubbles and making sure the tape was down smooth and firm.
And then it was time for the newest attempt. I knew the routine by now: tire levers, latex, valve core tool, tire pump. I prepared a dish of soapy water and spent some time cleaning all the old latex from the previous attempts with this tire (at least on the bead area).
With the tire on the rim and the valve core removed — and lots of soapy water around the bead area for lubrication and to spot any leaks — I charged up the compression chamber to 120psi. I connected the pump head to the valve and held my breath as I released the pressure. And … succeess! In just seconds I was rewarded with a couple of resounding pop! pop! noises as the tire bead seated on the rim.
I didn’t let my excitement stop me from immediately removing the pump (which let all the air out), pouring in some latex through the coreless valve, and then screwing tight the valve core. That done, and after rolling the wheel around in my hands to spread the latex throughout the inner surface, I pumped the tire up again, this time to 50psi. The tire quickly inflated and held the pressure.
With the tire inflated, I inspected the bead all the way around on both sides to make sure it was even and fully seated. It was. I noticed some hardened latex on the tread that was left over from my previous attempts, but I let it be. It won’t hurt anything and it will probably wear away with the first couple of weeks of riding.
Right after that I put the wheel on the scale: For the total wheel (tire, brake disc, etc.) the weight had dropped more than 230g. I was pleased as can be.
I’d love to say that the rear tire also went on at the first go, but it wasn’t to be. For the first few tries, the air just whooshed into the tire and then out around the bead, pretty much all the way around the time. I was treated to the sight of soap bubbles forming around the bead with each go. I’d do my best to work the tire into the rim, add more soapy water and try again. And listen as the air hissed out each time.
Finally after six or eight tries, I was ready to give up for the day. I pumped the compression chamber up to 120psi, put the pump head on the valve, and opened the tap. And listened … the tire was puffing up, and I wasn’t hearing all the air escaping. But there was no pop! I was just thinking it was another failure and was about to shut off the flow when, as the pressure dropped past the 40psi mark, there it was: pop! and then pop! Not as loud or sharp as for the front wheel, but enough. In my excitement to get the valve core in and inflate the tire again, I nearly forget to add the latex. But I got it done, and when that was done and I inserted the valve core, the tire was holding air. I’d done it, at long last.
The shocking result
I was so pleased I’d finally accomplished the conversion that I nearly forgot the comparison with Dionysus. In the end, Kuroko’s front wheel is just 120g heavier than Dionysus’s much slimmer (28mm) one (1,410g vs 1,289), while Kuroko’s rear wheel is actually 5% lighter (1,890g vs 1,992g)! It’s a bit of an apples-to-oranges comparison, though, as Kuroko’s wheels include the brake disc (which Dionysus lacks), while Dionysus’s wheels include the innertube. Finally, Dionysus’s much larger rear sprockets (maximum of 42T vs 34T) contribute to the weight there.
So what did I do differently this time?
I sure wish I knew. It would give me a confidence I still don’t have that I’d be able to remount a tire on the go if the need arose. Some combination of the care I took in cleaning the rim, renewing the rim tape and using soapy water all the way around seems to have done the trick. Meanwhile I learned that the second technique in Calvin Jones’s tutorial — removing the valve core and seating the tire on the rim before adding the latex — makes a lot less mess.
That’s not quite the end of the story. With tubeless tires I have to remove the old latex once or twice a year and add new. (I’ve used up a 500ml bottle to reach this point, so I ordered a new one. And Amazon reminded me I’d bought the first one in July 2019. So it’s taken me nearly a year to accomplish this.)
In addition to that, apparently this brand of tire is infamous for leaking a bit during the first two weeks or so of use. The sidewalls are so thin that they seep air until the latex has a chance to seal them up completely. So I need to check the tire pressure before each ride, and make sure I carry my pump with me at all times.