Zipp 303 SW review: The most striking feature of these all-road wheels is the integrated tire pressure monitoring system, but the US manufacturer delivers anything but standard equipment with this model. With their wide rims, the 303 SW wheels sit somewhere between road and gravel, and those who choose suitable tires can enjoy excellent performance with added benefits.
Zipp wheels were once prohibitively expensive professional equipment, but thankfully those days are over. While the manufacturer's rims were previously made exclusively in the USA, production of some models now takes place in SRAM's factories in Taiwan, which has a significant impact on prices. The most affordable model, the Zipp 303 S, costs just over €1.200, and the legendary "Dimples," which make not only golf balls but also wheels faster, start at just under €2.000.
Zipp 303 SW: Tire pressure sensor integrated into the rim
Priced at a cool 1.900 euros, the Zipp 303 SW features dimples and another special characteristic: these rims can measure tire pressure. Zipp has integrated its retrofittable "TyreWiz" pressure sensor completely into the 40 mm deep rim. But that's not the only special feature of this wheelset.
The positioning of the wheels is interesting, weighing in at a respectable 1.455 grams (666 g front / 789 g rear), though not extremely light. The Zipp 303 SW isn't a pure aero gravel wheelset – the US manufacturer offers the 303 XPLR with a 32 mm internal rim width and 40 mm external width for that. However, it's not a classic road bike wheelset either. The term "all-road" is more fitting for this wheelset, which boasts a 40 mm rim depth and a full 33 mm external width. The most striking feature of the hookless rims is the 4 mm wide rim shoulder, which results in a rather moderate internal width of 25 mm. This means tires from 30 mm wide and up can be mounted.
Zipp 303 SW: the highlights
- Hookless rims with a 25 mm internal width
- Rims 40 mm deep, 33 mm wide
- 20/20 Sapim CX Sprint spokes
- Zipp ZR1 hub set, pawl freewheel with 66 pitch
- Weight 1.455 g (VH 666 g / HR 789 g)
- RRP 1.900 euros
Things get really interesting at 32 mm tire width. That's when you reach a point where the tire is only slightly narrower than the rim itself, and this is considered a guarantee for optimal aerodynamics of the entire system – the 105% rule being the key. Goodyear developed special tires for Zipp, offered in 30 and 35 mm widths, but they aren't entirely convincing: the 30 mm tire, with a carcass width of under 70 mm, is only 29 mm wide, and it's also just 2,5 cm high. The solid Pirelli P-Zero Race TLR, which we used for the first few kilometers on the Zipp 303 SW, is 3 mm wider and 3 mm higher. But even this tire clearly shows the wide upper rim edge, which, incidentally, is designed to ensure rim stability in the event of hard impacts and also to prevent tire damage.
The game-changer for the Zipp wheelset is the new Pirelli P-Zero TLR SL-R, whose special casing design is intended to optimize the transition from tire to rim – and it works exceptionally well here. This Pirelli is also slightly narrower than the rim, but it ensures a visibly and noticeably smooth transition between the two components. The tubeless tire is easy to mount, so the Zipp wheels are quickly ready to ride – of course, the tire pressure monitoring system needs to be activated before setting off.
How does the built-in pressure gauge work? The sensor is housed in a small box that is inserted into the rim. The special tubeless valve is then pushed through from the inside; its knurled nut holds everything together. The valve stem has holes through which the tire pressure is transmitted to the sensor. These holes must not be blocked by sealant, which is why Zipp includes its own "injector" with a long tube. Special TPU inner tubes, also with perforated valve stems, are also available.
Like all electronic components in the SRAM/ZIPP ecosystem, the tire pressure gauge communicates with the AXS app, where the wheels can be added to a bike profile. Alternatively (for example, if you want to use the wheelset on different bikes), you can create a new profile and name it, for instance, "Zipp 303 SW". Here, the pressure of the front and rear wheels is displayed; you can also select minimum and maximum pressures. In fact, you must select them, because without this information, you miss out on a major advantage of the gauge: When activated by moving the wheels, the indicator light on the rim starts flashing – green if the pressure is within the selected range, red if it is too low or too high.
This means you don't even need to look at the app before setting off – just give the bike a quick shake, and the LEDs will indicate whether you need to pump up the tires before starting. If necessary, you'll know you've reached the desired pressure when the flashing light changes from red to green.
Special hoses with perforated valve stem
Step two is to pair the two pressure sensors with the bike computer. After all, you want to be informed about changes in tire pressure while you're out riding. This is relatively easy with the Wahoo app, but with one small drawback: the pressure can only be displayed in psi, not bar. So what now? You just have to remember that 4 bar corresponds to 58 psi and 4,5 bar to 65 psi. You shouldn't inflate 30mm tires to more than that anyway. The psi display on the bike computer primarily serves as a check: if you feel like you're riding slowly, you can now check the pressure without stopping.
Pumping with pinpoint accuracy without looking at the pressure gauge
And the integrated pressure measurement offers further advantages: Those inflating their tires with a hand pump without a pressure gauge can see exactly how much air is in them and no longer have to rely on the inaccurate thumb test. And of course, you can experiment with different pressures, for example on a gravel bike, and simply remember the optimal setting. The issue of "maximum pressure" is also particularly important when using hookless rims – for instance, if the bike has been standing in the sun for an extended period.
Aside from its special feature, the Zipp 303 SW is, of course, simply a wheelset – so what can it do as such? With its 40mm profile, it doesn't initially appear to be a purebred aero wheelset, but what it lacks in depth, it makes up for with its enormous width. Add to that the "dimples," and you have a system that feels incredibly fast and seems to have a definite advantage at high speeds compared to similarly deep models. On fast, twisty descents, the Zipp demonstrates stability in changing wind directions; this is complemented by the perceived high stiffness of the classic design with bent steel spokes. Remarkably, both the front and rear wheels manage with only 20 spokes each, where 24 are the norm.
The eight "missing" spokes mean a weight saving of 40 grams, although this isn't the Zipp 303 SW's strongest point. In the age of carbon spokes, some competitors have the edge here, but it's important to remember that the sensor weighs 17 grams per wheel, and the rim must be properly balanced to avoid imbalance. The increased impact resistance of the rim with its wide edge, which Zipp emphasizes, also comes at a price. However, the very pleasant riding characteristics and the pressure gauge feature clearly outweigh any potential weight disadvantage.
Fast with race tires, stable with all-road tires
Ultimately, the only question is which tires to pair with the wide Zipp wheels. The expensive Pirelli P-Zero TLR SL-R, with its optimized shape, is perhaps the best aerodynamic choice, and its extremely low rolling resistance also makes it fast. Those planning to use the wheelset on rough roads should still achieve good aerodynamics with a puncture-resistant all-road tire like the Specialized Mondo in 32 mm. And of course, the wheelset can be used on a gravel bike without hesitation. The fact that the Zipp 303 SW is usually offered at a significant discount only makes it even more attractive.