Shimano's RS80 wheelset is bringing Carbon wheels to the masses – at least wheels that look like they're made of Carbon, anyway. Lurking underneath is an alloy rim, which is good news for braking and general longevity, and Shimano say the combination of the two materials makes for a light, stiff and comfortable wheel. They would though, wouldn't they... how does the RS80 roll in real life?
The new wheelset uses exactly the same patented Carbon/alloy rim bonding process that you get on the Dura-Ace 7850 wheels. Shimano use a thinner Aluminium extrusion (0.6mm instead of the more usual 1–1.3mm) for the basic structure of the rim, and then bond on a Carbon outer layer. This is done with a – here comes the science bit – phosphoric acid bonding process that I'm not going to pretend to even understand, let alone explain. It certainly sounds more technologically advanced than glue though. As you can see from the cross section below, the rim is still primarily Aluminium, despite the Carbon good looks. We didn't cut ours up, incidentally... The cross section also show how asymmetric the rear rim is, the offset spokes help to even out the dishing and that makes for a stronger rear hoop.
The Carbon is sensibly concentrated (to a depth of 30 layers) around the spoke holes to reinforce the weak points on the rim, with a super thin two to four layer skin elsewhere. This achieves in the Carbon/Alu composite what other manufacturers (Fulcrum, for example) do by milling the Aluminium rim after it's been extruded.
16 bladed steel spokes tie the rims to Ultegra level hubs, which are understated in looks, smooth and well sealed. My only gripe is the Aluminum nipples, which are too easy to round off if you need to do any fettling. We didn't – ours stayed true throughout the testing miles.
At 1486g without skewers, this is a light wheelset for under £400, comfortably lighter than the Gipiemme Tecno 1.55 lights that we tested, and the Fulcrum Racing 3s that have been our benchmark £400 wheel for a while in terms of all-round performance. And do the stiffness claims hold up? Well, that's a bit of a muddy issue. In the lab (for 'lab' read 'shed') they don't - our standard test is to apply a lateral force to the rim and measure the deflection, and the RS80's 5mm deflection for 15kg load is higher than both the Gipiemme (4mm) and the Fulcrum (3mm).
Normally this is a pretty good indicator of how the wheel will perform, stiffness-wise, out on the road, and I was expecting noticeable flex and brake rub under effort. I didn't get it though – the RS80s were very well behaved most of the time. I could get them to touch the blocks if I really tried, but that's true of nearly every wheel I've ever ridden. They're not as stiff as a set of Fulcrum 3s, but they're stiff enough, and a good deal lighter for the same money. If you're an average-weight rider (I'm not, sadly) you probably wouldn't notice the difference in flex.
You might notice the difference in comfort though, because the RS80 is a comfortable wheel. Because it's relying on the Carbon in the rim to keep things stiff it has a fairly shallow profile, and this translates into a smooth ride, even on bad tarmac with the tyres pumped up to the max. With the tyres at normal pressure they're a great wheel for longer rides, the light weight making them fast uphill and the compliance giving them a good feel on the flats and the downs.
Overall, the RS80 is a well-designed, comfortable and good-looking wheelset. The Carbon layer is thin, but it does seem to make a difference to the ride, and the wheels are light and perform well for the money. Cutting rotating weight can make a big difference to performance and if you've got £400 to throw at an upgrade then the RS80s should definitely be on your list. Near the top.