During the Tour of the UAE, Thomas de Gendt suffered a mechanical failure. Adam Hansen's criticism of the hookless rim system after the race sparked widespread distrust among road cyclists regarding the use of hookless rims. Although this is a reliable system that has been thoroughly tested by the brand, certain aspects need to be considered when using it safely - precautions to take when using hookless rims.
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The hookless rims has injected fresh air into the development of rims for road bikes. A few years ago, clincher rims for races had almost no problems in terms of lightness, aerodynamics and rigidity, but it seemed that their development had come to a standstill. Later, the commitment of brand manufacturers to tubeless systems gradually replaced traditional tubeless wheels, making the structural design of carbon rims when carrying tires very complex, involving the arrangement of carbon fibers and the materials and resins used. This has also led to an increase in the average weight of wheel products in recent years instead of a decrease.
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Although brands have made rims lighter by improving the quality of available carbon fiber and resin, the use of hookless rims that does not have the typical bead hooks to fix the tires but relies on air pressure to press the tires against the rims, simplifies the manufacturing and lamination process of the rims. As a result, rims manufacturers no longer need to reinforce the fixed areas of the rims too much, and thus can produce lighter, more durable and cheaper carbon rims.
However, some problems were encountered during the use of the hookless rims. The first issue is the dimensional tolerance between the tire and rim manufacturers, which is particularly crucial for hookless rims, as the hookless design lacks the structure to fix the rubber.
When choosing tires for our hookless rims, the first step is to select a model that is fully compatible with the rims. For this reason, rims manufacturers usually provide a list of tire models that have been tested and guaranteed to be fully compatible. Although it might be unpleasant to be restricted to certain tire models, in this case, riding safety is of the utmost importance.
In terms of compatibility, choosing the suitable size of the tires is vital important. The inner tire width of the hookless rim is usually no less than 23 mm, which means the minimum tire size we can install is 700x28c. A 25-millimeter tire cannot fully support the edge of the rim and is thus prone to detachment.
Another important parameter for using hookless rims is air pressure. If inflating to 8 bar (approximately 120psi) on large-capacity vacuum tires is a thing of the past, then on hookless rims, this limit is even lower, usually set at 5 bar (approximately 70psi). This air pressure seems very low, but we must take into account that we are using 28-millimeter tires, whose inflation pressure is inherently lower than that of 25-millimeter tires. Furthermore, we need to break the traditional notion that higher air pressure can enhance rolling performance, as many studies in recent years have proved the opposite view. Wide tires and proper air release will provide us with a perfect balance between cushioning, rolling quality and grip, whether during acceleration or turning.
To install the tires without using tools, we first insert one side by hand into the central slot of the rim. This needs to be a bit deep so that there is space to insert the second side. Then, we also insert the second side into the central slot. It doesn't matter if we have to use a tire prying tool, because we don't have to worry about the inner tube being punctured. The purpose of doing this is to create an initial seal so that air can reach the entire area around the tire and simultaneously push the side of the tire to its final position.
If the tires are new, we can try to inflate them for the first time with an ordinary pump. When installing tires, removing the air nozzle core can make the airflow smoother, which is always helpful. However, for hookless tires, the initial inflation process will be slightly more complicated, so it will be more convenient to use a compressor. Another way to simplify this process is to spray the side walls of the tires with soapy water.
It is recommended not to add self-rehydration fluid immediately at this time, but to install the tires first. This can ensure that the fit between the air nozzle and the side wall and the wheel wall is correct. When inflating for the first time, we will adjust the air pressure to a value close to the maximum allowable value to ensure a perfect fit of the tires. We also check the uniform fit around by observing the fit line on the tire sidewall. All vacuum tires have this fit line.
Finally, we will add self-replenishing fluid through the syringe at the inflation valve and then inflate it to the normal operating pressure. At this point, the wheels can be moved in all directions to ensure that the self-replenishing fluid can cover every corner. For better sealing, it is recommended to ride immediately after inflation. Riding a few kilometers is sufficient for the liquid to be evenly distributed inside the tires.
Another key point is that for the tubeless ready system, if there is a puncture that cannot be repaired by self-rehydration fluid, an inner tube can be used. However, the inner tube should only be used when necessary so that it can be returned home and maintain the same air pressure as the original vacuum tube. Doing so poses a risk of re-puncturing due to hitting the rim. After a ride, the inner tube should not be used continuously, as this usually causes the tire to fail to fit properly, which may lead to the tire falling off next time. As the saying goes, "What kind of pot matches what kind of lid." tubeless tires and hookless rims are the perfect match.
