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Welcome back to the Bikerumor Ask A Stupid Question series! This week, we have the experts from Schwalbe, WTB, Maxxis and Vittoria on hand to answer a reader’s question about combinations of tire casing and rubber compounds.
Joining us this week are the following contributors:
- Ken Avery, SVP Product Development and Marketing Manager at Vittoria Industries, North America
- Clayton Wangbichler, Public Relations and Product Marketing Manager, WTB America
- Robert Mennen, Product Manager at Schwalbe
- Aaron Chamberlain, Assistant Marketing Manager at Maxxis
Why doesn’t there seem to be an option of a nice and supple trail casing combined with a nice and damped rubber compound? It seems like all damped rubbers are used on DH tires which for many reasons are a punishment to ride on flatter trails, and all more supple and easy rolling casings are paired with a fast rolling but also non-damping rubber.
Vittoria: Fair question actually, and one that is timely in these days of blurred lines between market segments.
First, a bit of background… Historically, casing materials and compounds have been chosen to best suit the needs of the intended use of the tread design. The thicker 2-ply casings of DH and Enduro tires offer protection, but also a fair bit of absorption since there is simply more material. Since these tires are designed for high speed and high impact, slow-rebound compounds are often used. These compounds are far less likely to “ping” off of rocks and roots (like a basketball on a court), and thereby increase traction.
So, to ask why these compounds aren’t typically available in a lighter, more supple casing, is logical.
The quick answer is, they are usually purpose built for racing, and since DH and Enduro are racing disciplines, it makes sense to spec them there. These compounds also can roll a touch slower, and typically wear faster than normal compounds, but since they provide a higher level of control, these trade-offs are worth it for DH and Enduro racers.
Since the lighter “Trail” style casing (as we call it at Vittoria), is meant for everyday riding (and is not a dedicated racing casing), it is built to balance durability, weight, and speed. The feel is much lighter and more supple than a 2-ply casing, and allows the tire to conform better to the terrain, which provides traction in addition to the compound’s formulation alone.
Therefore, the four separate Graphene compounds that were chosen for this application also balance grip and durability, with a longer expected lifespan than a dedicated race compound would offer.
Could tire brands simply use the same mold and casing material with the softest race compound, and make a new tire? Absolutely, and especially so given new trends that blend XC/Trail/Enduro sensibilities into one bike.
However, these new blends of casing and compounds would have to be carefully formulated to still meet the durability requirements, while offering a boost in grip. Otherwise, what the Trail rider would gain in grip, they would lose in durability, longevity, and rolling resistance.
For example, the tire may grip some surfaces better, but may be unstable at speed, or pinch flat more easily. This could also lead to tread delamination, and other issues down the road. For these reasons, tire brands are careful to match treads, casings, and compounds for the ultimate blend within a given use. In doing so, the rider receives the highest level of each performance metric, for the intended terrain.
That said, we are always working on new projects… so to close, I’ll just say “watch this space”.
WTB: We make exactly what you’re requesting! Casings and compounds are both divided up in two ways across all WTB tires. We differentiate between single and dual-ply casings using the terms Light and Tough. Light casing tires are single-ply and Tough casing tires are dual-ply.
Rubber compounds are divided up into High Grip or Fast Rolling. High Grip tires feature a blend of softer compounds that provide more damping and slower rebound. These are the tires that “grapple” with the trail more. Fast Rolling tires feature firmer compounds that increase rolling efficiency by both compressing and damping less. While it may seem counter-intuitive, Fast Rolling tires can actually punch into softer terrain better and increase traction in certain conditions.
Sounds like you’re looking for a Light casing tire with our High Grip compound. It provides a lightweight, supple casing without the weight and additional support of a dual-ply casing. The High Grip compound used in our Light tires is the same compound used in our burlier tires used for enduro and downhill riding. Don’t confuse “light” with “delicate” though. Most of our Light mountain tires also feature Slash Guard puncture protection to significantly improve sidewall protection.
Schwalbe: The properties of a tire are essentially determined by three factors: casing, tread compound and tread pattern. Depending on the intended use of a tire, the three factors are combined.
The main reason that we see well damped rubbers primarily on Gravity and DH tires is that well damped compounds like our Addix Ultra Soft offer the best grip and damping but often at the disadvantage of high rolling resistance and faster tire wear. The compound has by far the biggest impact on rolling resistance, much more than casing or tread pattern.
So, well damped rubber compounds combined with Trail or even XC casings instead of a gravity/DH casing would improve rolling resistance only by a small margin. The biggest advantage of this combination is the lower weight.
Additionally, from our experience, the more grip and damping a compound offers, the faster you usually go down and the more you benefit from a lateral stable casing and a higher puncture protection level. Please keep in mind that a more stable casing can be driven with lower air pressures for better suppleness.
To some extent you can compare this with a car: adding more horse power makes sense but at a certain degree you should also consider upgrading your brakes, tires and suspension.
Nevertheless, we at Schwalbe are constantly striving to minimize the contrasts. The invention of Silica compounds is one example that helped to reduce the rolling resistance without compromising grip.
Maxxis: Maxxis does offer a handful of our more aggressive tread patterns in lightweight casings (in our case EXO protection) in combination with our softest triple compound MaxxGrip rubber.
If you are asking why lower profile tread patterns don’t come in softer rubber, the reasoning would be tread life. Softer rubber wears faster and smaller knobs made from softer rubber would be more prone to tearing or ripping.
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