Now they’ve gone and done it! The tech that’s been the subject of a lot of our editorial this year on Slowtwitch – tubeless road wheels with hookless beads – has officially and fully jumped to the tri/tt world. Zipp announced today its 808 and 858 and the wheels are not the only thing that’s interesting. Also, the methodology of the testing to prove out these wheels, and the results that flow therefrom.
Here is what Zipp says about this wheel: “28mm tire is the optimum tire width to achieve lowest rolling resistance, and best aerodynamic performance.” That’s worth 300 posts on our Reader Forum according to my calculus. This is going to be a hotly contested statement. Both parts: the aerodynamics and the rolling resistance. I’m going to leave this here, for now, because I have a follow-up piece just on this.
Before you post your first facepalming rebuttal on our Forum, consider the testing protocol. It’s not wind tunnel and it’s not a drum calculating Crr. It’s field testing. If you can wrangle the accuracy and precision down you’ll get the best result, because field testing is real-world and it incorporates every source of drag simultaneously. Aero sensors offer the promise of a valid field test and this is what Zipp did for these new wheels.
There is one additional methodology used. Zipp owns a Rolling Road. The closest thing to this that I’ve seen is a treadmill for skiing, which I’ve seen at industry trade shows. A Rolling Road is a very large treadmill for bikes, and Zipp uses this for rolling resistance. More on this in a follow-up piece.
Zipp says that the new 808 is 1 watt more efficient than the prior 808, and that's about the least you get. The improvements increase from there, versus prior versions of these wheels. Note the graph above, and how the increases in power savings are not just with a 28mm tire slapped on the old wheel, but with the old wheel tested with its optimized tire (25mm) and the new wheel with its optimized tire (28mm).
Even a 30mm is pretty darned good, and for those of you who haven't had the chance to turn your bike into a Coup de Ville with these balloon tires, we who've been riding them since our Clement Campeon Del Mundos going back to the 1970s have enjoyed tires like these for a couple of generations, without the speed penalty many or most assumed was the case for these tire widths.
The most recent 808 Firecrest prior to today’s launch weight 1917g per pair. A pair of the new edition wheels weigh 1635g, and if you don’t want to do the math in your head the difference is 282g. Similarly the 858 NSW did weigh 1773g for the pair and the new versions weigh 1499g. This weight shaving of 274g brings an 80mm+ deep wheel under 1,500g per pair and that’s very rarely found in nature.
The 2023 model year 808 Firecrest sells for $2,300 a pair: $1125 front and $1175 rear. The 2023 model year 858NSW sells for $4,400 a pair.
The list of available tires for these wheels are found in 2 places: We maintain a global list of hookless wheel and tire compatability; and Zipp maintains its own list of tires compatible with its hookless wheels.
If you look at the chart below you’ll see the recommended pressures for these wheels when ridden with various tires. Note that these wheels have a 23mm internal bead width – quite wide, in keeping with the typical widths these days on hookless wheels – and for that bead width a 25mm tire is the narrowest you can use, per the ETRTO. If you’re just stuck on riding a 25mm tire, Zipp’s data notwithstanding, note that you run into a problem when the rider meets or exceeds 200lb. The optimal pressure for the fastest ride for that rider on a 25mm tire exceeds 5 bar, which is the ETRTO’s max pressure for hookless. That’s a pretty arbitrary number and certain wheel brands – ENVE notably – doesn’t consider 5 bar a hard stop. But Zipp does.
What you’ll see in the chart above is that a 200lb rider will not be able to put enough pressure in a 25mm tire to hit optimal performance. What we say here on Slowtwitch is that hookless may well be a superior tech for tubeless road, but at 28mm tires and larger. This, until the ETRTO agrees – and perhaps the tech evolves – so that 25mm tires are safely used with this tech at pressures above 5 bar.
However, there are two competing narratives here. The width of tires for which tubeless in general, and hookless in particular, is the optimal tech has been dropping (from 55mm to 40mm to 35mm to 32mm and now, arguably, to 28mm). Meanwhile, the optimal road tire width has been increasing (from 19mm to 21mm to 23mm to 25mm and, arguably, to 28mm). Accordingly, it may well be that hookless doesn’t need to work at pressures above 5 bar.
More on the new Zipp 858 NSW and 808 Firecrest wheels here.