Schwalbe have been trying to make a tubular cyclo-crosstire for more than three years and in September they finally succeeded in bringing the Racing Ralph HT to market. We're in the process of reviewing a set, but the story behind the tyres is worth hearing.
First for the stats: our production sample 'cross tires come in a 32mm width and weigh 392g on our scale. Schwalbe have also developed a set of tubular Racing Ralphs for mountain bikers, which come in a 26x2in size and weigh 540g. RRP for both tyres is US$145.
Both tubulars feature Schwalbe’s Racing Ralph tread pattern, synthetic EVO carcass and triple compound PaceStar rubber, which is made specifically for endurance racing and maximizing the tire’s rolling efficiency.
(For 2011, Schwalbe will offer a total of three triple compound tread options for their mountain bike tires. In addition to PaceStar, there's TrailStar, intended for trail and freeriding, and VertStar, which is so sticky that it requires different shock damping settings when compared to other, bouncier tires. All three use the same base compound but different center and side knob materials.)
Schwalbe's triple compound tread is the most advanced on the cyclo-cross circuit
Schwalbe took a long time to produce the Racing Ralph HT because of difficulties with the tubular manufacturing process. They started out looking for a partner to build a tubular casing for their tread technologies, but none of the manufacturers could produce a tire that would hold up to the German brand's rigorous testing without its tread or base tape delaminating from the casing.
“The biggest issue was the tread glue-up,” said Henry Horrocks, Schwalbe’s North American OE sales manager. “We let some sit for almost a year and the glue still wouldn’t totally set. It just never gets dry because of all the moisture in the glue when the tires are put together. [The solution] may have been as simple as changing the glue, but [the tire manufacturers] weren’t willing to change their process – 'it’s good enough for us, why isn’t it good enough for you?'.”
So, after more than two years of back and forth with two different tubular manufacturers, Schwalbe bit the bullet and built a new tubular production facility next door to their Indonesian clincher factory. The new 5,000sq ft facility handles the production of both off-road tubulars as well as Schwalbe’s road models.
After two years of development with partners, Schwalbe decided they'd have to make the tubular Racing Ralphs in their own factory
“It’s pretty much a clean room environment,” said Horrocks. “The temperature is maintained at a constant 68°F. It’s one of the places where guys like to work because it’s so comfortable [compared to the rest of the factory]. There’s zero humidity in that room.” The off-road tubulars meet what are probably the strictest testing standards of any cyclo-cross tubular available, and Horrocks says this makes them incredibly durable.
“The entire tire is pretty much watertight,” he said. “Moisture will not affect it. You have the synthetic fibers [sidewall], the latex tube, the latex coated sidewall and even the base tape has a latex coating that you don’t need to scuff up; I’ve used it in both situations and scuffing it doesn’t seem to help at all. I prefer to leave it intact: that way the tire stays completely sealed.”
The Racing Ralph tread seems to be somewhere in between the intermediate and aggressive mud treads other manufacturers offer
Alongside the new tubulars, Schwalbe have developed a new latex inner tube. Latex tubes offer lower rolling resistance than their butyl counterparts but they’re finicky to produce and those made via the traditional method of dipping a pipe in latex generally have wildly varying wall thicknesses and noticeable seams.
“The wall thickness through our tubes is exactly the same,” said Horrocks. “That reduces air loss and it fills more consistently like a butyl tube [so you don’t get the blowouts created by a thin spot].”
To extrude their latex tubes, Schwalbe use a modified version of the machine they use to make butyl tubes. They also have a way of welding the tubes’ seams so there's no material overlap. “Jared [Graves] was running them on his four-cross bike,” said Horrocks. “It’s possible [that we'll sell them].”
Look for a full review of the Racing Ralph HT tubular on BikeRadar later this month.