The terms “hookless rims”, “hookless technology” or “hookless tires” have been making a stunning career lately and are conquering the world of sports bikes by storm – first MTB, then gravel, and recently also road racers. However, many riders approach this topic with distance, mainly because they don’t really know what could be wrong with the rims with the traditional flange and how hookless technology could be better than them. This type of distrust and skepticism, which always accompanies new solutions, is one thing, and the specific concerns that arise are another. Many people are afraid of a higher risk of the tire slipping off the flange, mainly due to the higher pressures used in road tires than in mountain or gravel ones. We wrote this article to dispel the fog of uncertainty around this inevitable revolution. And why inevitable – we invite you to read.
To put it simply, a hookless rim differs from a traditional rim primarily and above all by the absence of hooks on the bead seat, which the tire is hooked onto. The rim bead seat design is described in detail in ISO (International Organization for Standardization) 5775-2:2021, which we used in the design of our Pulsar or Hyperion rims.
Most riders are already familiar with the concept of tubeless tires, which are filled with sealant instead of a traditional inner tube. Almost all high-end wheels have rims with rims that are compatible with tubeless tires. However, it must be admitted that not everyone is convinced by this concept and many remain faithful to traditional inner tubes. But to the point. Hookless rims (referred to by the abbreviation TSS, which can be decoded as Tubeless Straight Side) can be used with both inner tubes and in a tubeless system, but the tire must be compatible with hookless rims. We will return to this topic when discussing the compatibility of hookless wheels with tires.
Let’s be honest – hookless technology and hookless wheels wouldn’t have caused such a stir in the cycling world if they didn’t come with specific benefits. And this type of rim design has a number of really significant advantages. The most important of them are:
Hookless technology widens the rims, which allows for lower tire pressure. This in turn has a number of positive and very noticeable consequences. First of all, it reduces rolling resistance. According to ZIPP, the power savings for a cyclist can range from a few to even 40 watts, depending on the quality of the surface – the worse the asphalt, the lower the power losses. In other words, hookless wheels free the cyclist from the need to reduce speed due to poor road conditions. You can simply ride faster over potholes and cracked old asphalt – which is the main feature of our local roads. “Smoother is faster” – as Specialized claims, and it’s probably safe to believe them, given the number of wins in the Paris-Roubaix race. Lower tire pressure also improves ride comfort and grip, which in turn allows for longer rides without physical discomfort and riding with greater confidence, adrenaline, or in changing weather conditions.
Reducing aerodynamic drag is a proven and undisputed way to improve speed and efficiency. Hookless technology allows for a better fit between the tire and the rim. Zipp engineers developed the so-called “105% Rule”, which states that for optimal aerodynamics, the external width of the rim should be 105% of the width of the tire. We are able to fully apply this rule in the Pulsar 45 wheelsets with a tire of nominal width 28c.
To take advantage of the benefits of hookless rims, they must be used with the correct tires. However, this is where the problems start, as not all tire manufacturers are as enthusiastic about this technology as the companies that design and manufacture wheels. The basic compatibility principle is as follows: only and exclusively tubeless-ready tires can be mounted on hookless rims. There is no obligation to ride on milk, you can put tubes in them, but the tire must have the TLE, TLR, UST or similar marking, which testifies to the fit to the tubeless system. Some road tires, especially older models, have the inscription “mount only on hooked rims” on the edge.
Hookless rims have an increased internal width compared to those with a hook at the same external width. This raises further doubts about the compatibility of tires with hookless rims. The European Tyre and Rim Technical Organization (ETRTO) protects the safety of European tire users (not only cyclists), ie in fact all Europeans who ride on something that has wheels with tires. Every year it publishes updates that detail the compatibility of rims and tires. Currently, 28c tires in road bikes are already the standard. Moreover, we can expect further enlargement of this dimension in the coming years. The change from rim brakes to disc brakes freed tires and rims from the tight shackles of the space inside the arms of traditional rim brakes.
Another potential problem with switching to hookless is the lower tolerance for allowable pressure. Here too, ETRTO comes to the rescue, limiting the maximum pressure to which tires on hookless rims can be inflated to 5 bar in the latest standard. This may seem like a small amount. Here we recommend taking a look at our previous blog post – Predicted pressure drop, in which we explain in detail why the optimal pressure is not always equal to the maximum. For example, a 75-kg athlete should pump his 28c tires mounted on Pulsar wheels with an internal width of 25 mm to about 4 bar. This is the optimal pressure for him to fully exploit the capabilities of his bike. You can find a pressure calculator that takes into account a number of factors in the link below:
https://cycling-sport.com/en/resources/tire-pressure-calculator
It’s time to answer the question of why the “hookless revolution” is inevitable. In our opinion, soon all high-quality wheels on carbon rims will have hookless rims, whether you like it or not. Bicycle manufacturers are constantly looking for ways to improve their products, and every improvement is paid for with some restrictions. The truth is, modern bicycle wheels are already so perfect that the bicycle industry really has to stretch itself and sweat to come up with something new and significantly better. We personally like the trend associated with hookless technology, although we admit that it is becoming increasingly difficult to keep up with the ever-increasing standards, which in turn complicate the issue of compatibility of individual components.
If you have any questions or doubts about Dandy Horse hookless wheels, their selection and configuration, please do not hesitate to contact us. We are always happy to answer and offer advice.
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