The time has come when cross racers engage in fierce battles all over the place.
Even while feeling tossed about by spells like "shoukaku" and "koukaku," they keep pedaling, even when covered in mud.
Tubular tires are frequently used in these CX race scenes.
Although the options for tubeless tires have increased recently, most of the top categories still use tubular tires. Of course, there is a reason why they are used this way.
1. The tires are lightweight (and the rims for tubular tires also have a simpler structure, making them lighter than clincher rims in many cases).
2. They are resistant to pinch flats, allowing for lower tire pressure.
3. They are often supple, and combined with the lower air pressure, they provide extremely solid grip performance.
4. The tan-wall (side skin) tires often seen on tubulars look professional.
Even if we set aside point 4, points 1 through 3 significantly affect the ride, so many people feel they are necessary to aim for a higher level of performance. You might think everyone should just use tubulars without hesitation, but these tires do have a few drawbacks.
1. Generally, CX tubular tires are quite expensive.
2. If you get a puncture, that's it. (In some cases, you might be able to get by with tire sealant).
3. Because they are bonded with rim cement (glue), the installation is time-consuming and quite a demanding task.
4. If the installation fails, the rims and tires get covered in sticky cement.
These are the points that can be mentioned.
However, in the world of racing, these points are not much of an issue, which is why tubular tires are still used in race scenes today.
While not very common among road tires, the issue of "tires peeling off the rim" is a frequent problem seen with tubular tires in CX.
Since they are bonded with an adhesive called rim cement, it is difficult to prevent it 100%, but it goes without saying that a tire coming off during a race is unacceptable.
Why is it that tire detachment happens so easily in CX?
The cause is often believed to be "mud"—the one character I would choose to describe CX.
It is said that moisture contained in the mud soaks into the seam on the inner side of the tubular tire—the part referred to as the "diaper" or "fundoshi"—and weakens the adhesive bond, causing the tire to peel off.
In road cycling, because you ride with high tire pressure, the air pressure prevents water from seeping in, making detachment issues less likely. However, in CX, you often ride with air pressure dropped to below 2 bar, and because the tires are wider than road tires, significant lateral force is applied during cornering. As a result, they peel right off.
To ensure that everyone can use tubular tires with peace of mind, we at Circles perform a "CX special tire installation" (I wouldn't go as far as calling it a "deadly technique," but still). (The introduction was long, but this is the important part! lol)
1: Inflate the tire to 0.5–1.0 bar and temporarily mount it on the rim to let it stretch and settle.
Leaving it mounted for about a day stretches the tire, making the actual bonding process easier.
2: Lightly scuff the tire-bonding surface of the rim with coarse sandpaper.
If re-mounting on a rim that was previously used, remove the remaining rim cement to a certain extent.
3: Apply a thin layer of rim cement and let it dry for 24 hours.
4: Apply a second thin layer of cement over the dried layer and let it dry for another 24 hours.
5: Confirm that the bonding surfaces of the tire and rim fit perfectly together as shown in the diagram. (If there is no problem, proceed to 6.) If there is a gap of 1mm or more between the bonding surfaces, or if you want an even stronger bond, we recommend applying CX TAPE here.
CX TAPE is not your typical double-sided tape for tubulars; it is a special tape developed for CX that fuses with the rim cement to create a much stronger bond.
Apply a thin layer of rim cement before attaching the CX TAPE, then let it dry for 24 hours after applying the tape.
After that, apply another layer of rim cement and let it dry for 24 hours.
At this point, at least 4 days have passed... It might sound mind-numbing, but it is all for the sake of the tire.
6: Finally, it is time to bond.
Inflate the tire to 0.5–1.0 bar and apply a thin layer of rim cement to the "fundoshi" (the inner bonding surface of the tire).
7: Apply a thin layer of rim cement to the rim side as well.
8: Mount the tire onto the rim.
Press the tire firmly onto the rim. Start from the valve position and apply force evenly to both sides all the way around.
9: Once the tire is on the rim, inflate it to about 2 bar.
10: Check if the tire is centered on the rim.
Ensure the "fundoshi" is not protruding too much from the rim by properly aligning it.
11: Wipe away any excess rim cement that has seeped out to the sides.
12: After that, let it dry for 24 hours and the bonding is complete. All's well that ends well!
13: Additionally, for those using Dugast tires, we recommend applying Aquasure as a protective agent for the tire sidewalls. Using rubber gloves, apply a thin layer of Aquasure to the tire sides. Spread it evenly between the rim and the tire to prevent water intrusion. We also recommend applying it around the valve hole. Once finished, let it dry for 10 hours and it is complete.
How about that?
I'm sure it was tough to keep reading halfway through, but proper bonding really does require a fair amount of time and effort.
But this allows you to stand on the starting line of a race with peace of mind, so if you are ever in trouble, please feel free to consult with Circles.
CX SPECIAL Installation: 2,500 yen per tire
CX SPECIAL Installation with CX TAPE: 3,000 yen per tire
Aquasure Coating: 1,000 yen per tire (includes cost of Aquasure)
We currently have a wide variety of patterns in stock for Dugast tires, which boast an incredibly high share even among top racers. Of course, we also welcome requests for installation only if you bring your own tires.