The times are changing quickly. From our memories, the standard road wheel width was always 19mm, and the tires measured 23mm. We used to think that quicker speeds came from narrower road tires, implying more tire pressure. At lower pressure, bigger tires do, however, provide less rolling resistance and better comfort. Low tire pressure has entirely changed the world of road bikes as tubeless tires become more and more prevalent on them. The most notable development is that road bikes can now comfortably negotiate bumpy terrain and have increasing adaptability. While endurance road bikes might be lighter and more aerodynamic, aerodynamic road bikes can also be employed for this aim.
To complement bigger tires, mainstream road tires are currently moving from 25mm to 28mm. Purchasing wheelsets smaller than 21mm inner width looks antiquated now; 23mm, 22mm, and 25mm inner widths are becoming more and more popular. Road wheelsets have been split into two schools of view: 21mm and 23mm inner widths. Still unresolved is the average wheelset inner width.
From the standpoint of worldwide big-brand wheelsets, Roval, Vision, and Shimano are 21mm internal width schools; Bontrager, Enve, and Zipp are 23mm schools (the hookless wheel also has 25mm internal width); Campagnolo is transitioning from 21mm to 23mm. Internal widths run 50/50 between 21 and 23 mm.
From 19mm To 21mm: A Magical Transformation
Starting with a 21mm internal width will help you to completely embrace tubeless tires. This is so because tubeless tires mostly benefit from their ability to expand more and require lower pressures via broader internal width. It also offers better lateral support and helps to prevent the tire from bulging out, therefore lowering the possibility of tire turning sideways on lower pressures.
From 21mm To 23mm: The Tires Are Wider!
You are adding an extra 2mm when you widen your wheel by 2mm, say from 21mm to 23mm. This is not as important, though, as moving from 19mm to 21mm. The lateral support of the tire is not clearly different between 21mm and 23mm. But the tire's extra 1-2mm expansion made possible by the 23mm internal width lets you utilize lower tire pressure, roughly 5–10 psi, for more comfort without compromising roll resistance. For example, a 21mm wheelset will have 28mm width if you place Michelin POWER CUP 25c tires on it. Mounting them on a 23mm wheelset will result in 1.4mm widening—that is, 29.4mm wide. This effect is akin to having larger tires without weight added.
A 23mm inner-width wheel set is advised for individuals who would rather not utilize tubeless tires. This is so because, compared to a tubeless tire, the inner tube consumes some space, therefore lowering the air capacity of an open tire. Consequently, the tire pressure has to be raised by 5–10 psi even if the tire width and rider weight remain identical. Usually, when compared to a 21mm wheelset, the 23mm inner width wheelset can offset this disadvantage since the tire can expand wider. Still, it cannot be used with tubeless tires or ultra-low tire pressure since snakebite will produce a flat tire.
23mm Inside Width Is Better Suited For 28mm Tires
Only endurance road bikes had 28mm tires not too long ago. But today 28mm is a race road bike tire more comfortable than 25/26mm tires. Comfort might sometimes equate with speed. Better fitting for 28-mm tires is the 23-mm inner width than the 21-mm. A wheelset having a 23mm inner width usually has an outside width of 30mm or more. For 28mm tires, this offers a more aerodynamic fit.
Conclusion
Usually, the inner widths of the 21mm and 23mm wheelsets are the same. Tubeless tires fit both hooked 21mm and hookless 23mm wheelsets, and their actual use is not much different. On lower tubeless tire pressure (21mm inner width), the 23mm inner width for open tires is better matched and offers more comfort. The 23mm inner width is more useful for big riders wishing to use 28mm or wider tires.
