Carbon fiber wheels may be all the rage but they have some major drawbacks. Braking performance is inferior to that of alloy brake tracks, it's generally harder to get tubular tires to stick and stay stuck, and the best performers command a high price.
Enter Mavic's Ksyrium SR – an alloy tubular wheelset (in fact, the only Ksyrium with the option of a tubular rim) with features so impressive, they may make you think twice about opting for carbon. Unfortunately, like with the best carbon wheels, you pay for the Ksyrium SR's performance.
Ride & handling: Super-solid performance on all fronts
We have friends still riding and racing on first- and second-generation Ksyriums – wheels that are 10 years old – so we've no concerns when it comes to durability. Sticky freehubs used to be a common complaint, because those original wheels used an inner hub shell to freehub bushing that was easily contaminated. However, this was easily fixed with routine maintenance and the freehub on our rear Ksyrium SR hasn't stuck or slowed despite being put through the cyclo-cross ringer.
Both front and rear wheels are plenty stiff, laterally – more so than a conventionally laced steel spoked wheel – but they also remain reasonably comfortable thanks to the low rim depth (21mm front, 25mm rear) and the lower pressures afforded by the tubular tires. The use of 18 of Mavic's proven Zicral alloy spokes in the front wheel gives us more confidence in the SR than the company's carbon-spoked R-Sys, and we can't detect any appreciable loss in stiffness.
The Ksyrium SR uses all Zicral spokes in the front wheel
The rear wheel's stiffness under hard pedaling is noticeable, and may be attributed to the Tracomp carbon spokes/lacing used on the non-drive side. We're comfortable with the use of carbon spokes here, although the 40g weight saving they provide comes at a high cost – the Ksyrium SR costs $250 more than the Ksyrium SL, which relies entirely on Zicral spokes. The 25mm rim depth also probably contributes to the slightly stiffer feel.
The hubs are classic Mavic, which is to say their steel bearings feel better than some other manufacturers' ceramic versions right out of the box, despite being better sealed and generally more durable. Our hubs only ran smoother as the test went on, despite testing in the less than favorable conditions of cyclo-cross. And the freehub gave us zero problems during three months of use, complete with a couple of mud fests, power washes and low temperature slogs.
Braking with the SR is exceptional compared to the carbon competition, though we did notice slightly higher than average wear on the brake track after just a half dozen muddy races. Modulation, heat management on long road descents and the general feeling of 'bite' from pads to rim is good.
The front hub uses a carbon shell with alloy flanges
At 1,452g (669g front, 783g rear), the SRs are heavier than the lightest carbon wheels but they still accelerate quickly and with a detectable snap. There's an aerodynamic cost to the shallow rims, though, and the profile can act like a shelf in deep sand and mud.
It comes down to this: the Ksyrium SRs are heavier and less aero than an equivalent carbon wheelset, but offer better braking and durability. That makes them a compelling choice for the 'cross racer looking for one set of tubulars that will do everything. They're also a good option for those riding in packs on the road, either racing or in gran fondo type events, where they can hide from the wind but capitalize on the benefits of better brake performance and tubulars.
Finally, the SRs are great wheels for those who want to ride tubular tires every day, simply for their feel. These folks won't want to give up an alloy braking surface, especially in the mountains, but might want something a bit sexier than a simple box section rim. It's a shame, therefore, that our Ksyrium SR rim decals failed to hold up to power washing.
We lost some stickers in the clean-up
Materials & construction: Mavic's classics – Zicral, Fore, Maxtal, SUP, ISM
The Ksyrium SR uses an array of Mavic's proprietary technologies, including Zicral alloy spokes, Fore drilled rims, Maxtal proprietary alloy, SUP welded joints and machined ISM outer rim profiles. It's the Fore rim drilling that adds the most to the wheelset, in our opinion. Mavic use a heated bit to drill and thread only the outer wall of the rim extrusion, leaving the inner tire bed unpunctured and sealed.
This means the tubular gluing surface is uninterrupted and increased, and there's much less chance of water or other muck penetrating the glue bond. The result is better adhesion than with just about any other alloy rim on the market, including unpunctured options from Fulcrum and Campagnolo. The unpunctured tire bed also makes up for the rim being narrower than the contemporary crop of wide rims.
The Zicral spokes, though expensive and not particularly aero, are strong and provide a slightly stiffer and more responsive ride than steel spokes. They're also easy to replace when broken and after 10 years, relatively common in shops. Mavic's hubs are still the epitome of quality in our eyes, when it comes to both bearings and their ease of adjustment through the QRM+ design. We also like the increased durability of the steel FTS-L freehub design and the fact that the freehub can be rebuilt in about 10 minutes.
A big benefit of the Ksyrium tubular rim is its resistance to contamination of the gluing surface
Original: BikeRadar.com Road Bikes & Gear