Tubular vs Clincher Comparison

The Schwalbe Rocket Ron was one of our favorite clincher cyclocross tyres (read the review here). Its fantastic performance in the mud made it the go-to tyre towards the end of the British cyclocross season. After chatting with Schwalbe UK, we secured a set of the tubular Rocket Rons to test side-by side. The latest tubular and clincher Rocket Ron versions share the same tread design, same 150 thread per inch casing, and even the same rubber compounds on the tread. This was as close to a perfect competition between philosophies as we were going to find.

Tubular and clincher Rocket Rons ready for action

We were particularly interested in the clincher vs tubular contest with this tyre, as the Rocket Ron is offered as both a CX tyre and mountain bike tyre. Many of the frequent tread design and rubber changes are driven by MTB clincher testing. Additionally, although the tyres share common ancestry, their dimensions are quite different. The clincher is 2 millimeters wider and 5 millimeters deeper than the tubular. Despite this difference, the tread spacing and knob size is just about the same. This means the tubular tyre tread reaches further down the sidewall. Would these differences help the Rocket Ron clincher get closer in performance to its tubular cousin, or would the tubular knock the clincher back in the muddy fields?

THE WHEELS

To even the contest up even more, we carefully selected two wheelsets for the test that would bring the best from both tyre types. We mounted our clincher on the Ritchey Vantage WCS 29er disc brake wheel and the tubular on the Remerx RTX cyclocross disc brake wheel. The two wheels are similar in design, both alloy, in the 1550 gram weight range, with a focus on a durable, lightweight race wheel.

THE SETUP

The clincher wheel choice is an interesting one for this test. We selected the Ritchey both because it is light, but also as a 29er mountain bike wheel because it is wide. This width, combined with a latex tube, helps the Rocket Ron clincher because we’re able to run a lower tyre pressure without pinch flatting. We’ll explain pinch flats, wide rims, and the benefits of low tyre pressures later in the article.

The Remerx wheel is not as wide as the Ritchey, but still broad enough to bond the entire tubular tape. The rim bed (where the tubular glues to the rim) is also less concave than some other road wheels which ensures a solid bond with a tubular cyclocross tyre. We applied three coats of glue to the rim and two to the tyre before mounting the Rocket Ron on the Remerx. A really secure tyre mount is required when riding a tubular because, unlike road tyres, cyclocross tubulars rely on the glue more than tyre pressure to hold the tyre to the rim. As pressure increases, the tyre expands against the rim causing a better bond, as it decreases that bond lessens.

THE COMPETITION

We rode the tubular and clincher Rocket Rons throughout the winter both in training and in races. Most of our riding and racing during this period was in wet grass, light mud, and heavy mud. We finished the comparison with a two hour alternating lap comparison to help crystallize our assessment.

The test environment (aka a park)

THE OUTCOME

Are Rocket Ron tubulars a better cyclocross racing tyre than Rocket Ron clinchers? Simply put, yes. Are Rocket Ron tubulars so much better that everyone reading this article should rush out to purchase a few sets of tubular cross wheels? Probably not. Why are the Rocket Ron tubulars better than the clinchers? Two words. Tyre pressure.

On the wide-rimmed Ritchey wheel with a latex tube, we ran the clincher tyre pressures ranging from 30-35 psi. This was a safe pressure on the wet, grassy courses in the UK. The tubular inflations ranged from 22-28 psi in the same conditions. Both of these pressure settings were 2-15 psi lower than the minimums recommended by Schwalbe, but we never flatted a tyre even in race conditions where speeds are higher and lines are less careful. Why does a lower tyre pressure matter? In cyclocross, a lower pressure provides at least two benefits 1) the tyre can absorb bumps and irregularities, smoothing and speeding the ride and 2) the tyre can wrinkle and conform to the ground when under braking, acceleration, or cornering pressure which keeps more tread on the ground when the rider needs it most. These desired outcomes also motivate cyclocross tyre suppliers to include very high thread count casings. The higher the thread count, the more supple the tyre. The more supple the tyre, the more it will conform to the ground under low pressures.

These low pressures expose the achilles heel of a clincher in cyclocross racing; pinch flats. A pinch flat occurs when the tyre’s tube is squashed between the rim and the ground with enough force to either rip or bust the tube. This risk can be mitigated with a latex tube, which is more resistant to pinches (and lighter as well) than a butyl tube, and with a wider rim, which changes the tyre profile to a less pinch-likely profile. A wider wheel changes the sidewall shape, changing from a balloon shape from the rim to the top of the casing to a more rounded shape. This also allows for a lower tyre pressure with less risk of pinch flat because the tyre is less likely to get caught between the rim and the ground under compression. Tubulars can also pinch flat, but the lack of a rim “edge” makes this much less likely. A sudden bump distributes force across the tube and tyre rather than concentrating it on the clincher sidewall edge. This significantly drops the risk of pinch flatting. Thus, a rider can run tubulars with much lower tyre pressures than even well-prepared, cyclocross clinchers.