New Schwalbe Albert: Radial different - Schwalbe revolutionises MTB tyres with unique construction

The tyre contact area of mountain bike tyres is just a third of the size of a shoe. Not really much to transfer steering and driving forces off-road. When riding over obstacles such as roots or stones, the surface area becomes even smaller. So what can be done to get the best out of the contact area or even increase it, the Schwalbe engineers asked themselves?

Possible solutions would be to reduce the carcass plies to give the tyre more flexibility. However, this would result in less stability and puncture protection. Another solution would be to reduce the tyre pressure. Here too, the risk of punctures increases with less riding stability and again requires inserts that add weight.

Schwalbe is therefore introducing tyres with a radial carcass in order to optimise the tyre contact area without accepting disadvantages such as puncture risk and instability. What is state of the art in the car and motorbike sector is now also coming to the bicycle sector. The term radial tyre is used when the threads of the carcass are arranged at a 90 degree angle to the direction of travel. Car and motorbike tyres typically have an R in the size designation, which indicates a radial tyre. In bicycle tyres, however, the carcass plies are usually arranged at an angle of 45 degrees to the direction of travel. This is referred to as a diagonal tyre.

What is the effect of the new alignment of the carcass plies?

The radial alignment of the carcass plies alone (on the right in the graphic below) means that Schwalbe has increased the tyre contact area by 30 percent. More surface area means nothing other than more grip. And this, mind you, with identical tyre pressure. If the tyre pressure of the new design is increased by 0.5 bar, the contact area is still ten percent larger, according to Schwalbe.

The radial arrangement of the carcass threads also increases the flexibility and adaptability of the tyre to the ground. The tyre adapts much better to the contours of the ground, absorbs obstacles better and provides more ground contact. When riding over small roots, the tyre Tyres in front of and behind the root on the ground and is not exclusively on the root for a short time, as is the case with conventional tyres.

In addition, the new carcass is said to have slightly better damping, which should have a positive effect on off-road control and the riding experience in general.

Advantages:

• More grip
• Greater comfort
• Better damping
• Equally high cut and puncture protection

Disadvantages:

• Minimally higher rolling resistance
• Slightly poorer puncture protection with identical air pressure
• Relatively expensive

Radial different: New Schwalbe tyres with radial carcass

The new radial carcass will be available with three different tread patterns: The Shredda, an E-MTB tyre especially for muddy, loose ground conditions. The familiar Magic Mary and the new Albert Pro tread pattern. Both the Magic Mary and the Albert Pro are available in a gravity and a trail version. The Shredda is only available in the heavy gravity version with Ultra Soft rubber compound.

The new Albert Pro is an all-round tyre that is best positioned on bikes with a suspension travel of 150 millimetres or more. The tread pattern can be used on both the front and rear wheel. Thanks to the slightly narrower lug spacing compared to the Magic Mary, the Albert should optimally bring its strengths to the ground, especially with the new flexible carcass. Magic Mary and Albert Pro are available in soft and ultra-soft rubber compounds.

The trail tyres are priced at 73.90 euros and the gravity models at 79.90 euros. In terms of weight, the trail version of the Albert in 29 inches weighs between 1080 and 1160 grams (BIKE measurements). The gravity version of the Albert weighs in at 1250 grams in 29 inches.

Interesting fact: The new radial tyres from Schwalbe will only be available in 2.5 and 2.6 inch widths, but tend to be somewhat narrower than conventional Schwalbe tyres. On a 30 mm rim, the maximum width (lugs) of the 2.5-inch Albert is 60 millimetres. The 2.6-inch tyre is 63 millimetres wide.

First riding impression: The Schwalbe Albert Gravity radial in a practical test

Even the first few metres on the new radial tyres are promising and noticeably different. Even in the car park, it quickly becomes clear that the new tyre construction feels fundamentally different compared to a standard tyre. Prepared with the usual air pressure, you get the feeling of riding a much softer, more flexible tyre - as if you had half a bar less pressure in the tyre.

However, the stability check on grippy tarmac proves that the tyre pressure is correct. Even hard cornering and maximum pushing do not cause the tyres to buckle. There is no trace of instability. However, the big surprise awaits off-road. The tyres practically inhale small roots or small edges and stones. Fine bumps are completely swallowed up. Riding comfort is noticeably higher. As soon as the terrain becomes steeper and looser, traction is required. The new tyres interlock reliably with the ground and offer an unprecedented level of grip even on transverse roots and loose stones.

The new radial tyres also perform impressively downhill. The high level of grip and the increased damping ensure excellent interlocking with the ground and increase the feeling of safety. After the first test rides, our conclusion is extremely positive. The new radial tyres impressively provide a higher level of grip and safety.

Roots, small edges or stones: The new Schwalbe tyres with radial carcass completely swallow up small bumps, making for a noticeably more comfortable ride. At the same time, they offer unprecedented traction. The new radial tyres from Schwalbe also impressively provide a higher level of grip and safety when riding downhill.

Interview with Carl Kämper, Product Manager and Developer at Schwalbe

BIKE: Radial tyres are state of the art in the car and motorbike sector. Diagonal tyres are still used for bicycle tyres. How did you come up with the idea of transferring the radial carcass to MTB tyres?

Carl Kämper: Our aim was to combine an adaptable, flexible tyre with high puncture protection. We therefore spent a long time looking into the subject of inserts. However, the most favourable, easiest and most uncomplicated puncture protection is and remains air pressure. Although a higher air pressure effectively reduces punctures, it unfortunately has a massive negative impact on ride feel and grip. The aim was therefore to run more air without losing sensitivity and grip. Unfortunately, simply reducing the casing plies did not work. The brilliant idea came from a motorbike trial video. The radial tyres used increase the contact area and adapt extremely well to the ground. We also quickly recognised the potential for downhill use. The radial tyres allow higher air pressures, which increases puncture protection, but still offer more grip and comfort.

What exactly are the advantages over a conventional diagonal carcass?

The biggest advantage lies in the utilisation of the contact area. Compared to a sole impression with a size 42 shoe, the tyre contact area is only about one third. We bikers are practically dancing through the forest in ballerinas. As a trail is anything but homogeneous, this area decreases every time you roll over bumps. So you have to make sure that the contact area always stays on the ground. However, low air pressure has too many disadvantages. With the new radial construction, we can run a thick or stable carcass and the tyre still follows the ground much better. The radial tyre moulds itself around roots and thus makes contact in front of and behind the obstacle. In addition, the contact area is 30 percent larger than with a standard tyre at the same air pressure.

What are the disadvantages of radial tyres? What about rolling resistance, puncture protection, weight and riding stability?

A conventional Schwalbe Magic Mary with Superground casing and soft rubber compound rolls at 31 watts at 25 km/h on the roller dynamometer. Its counterpart with a radial carcass rolls around 20 per cent worse at 37 watts because more rubber has to be deformed due to the larger contact area. With the new Albert, which has an optimised tread, we achieve 34 watts. In off-road terrain, where the radial tyre can show off its flexibility, it rolls even faster, as numerous tests have shown. As far as cut and puncture protection is concerned, the radial tyres are identical because we use the same carcass material. Only the puncture protection deteriorates by around seven to eight percent with identical tyre pressure, as the tyre deflects more linearly. However, thanks to the increased flexibility, the tyre offers much more room for manoeuvre in terms of air pressure, which means that the puncture protection can be increased and the riding characteristics improved at the same time. The weight does not change because - as already mentioned - the same material is used. Our initial concern that the tyre might feel undefined or less stable quickly turned out to be unfounded.

The tyre was originally developed for technical uphills with the E-MTB and is designed to maximise grip. However, the ride feel is also very noticeable downhill. Are other applications conceivable?

The benefit was originally E-MTB-driven, in order to maximise grip in all respects without compromising on puncture protection. Almost at the same time, however, the development for downhill racing went in a very similar direction. A flexible tyre, without compromising on puncture protection, offers advantages in many situations.

In the downhill, a certain Amaury Pierron, who won the last two World Cups (Val di Sole and Les Gets) by a massive margin in extremely adverse track conditions, is said to have ridden on the new carcass technology.

Yes, that's right. We have been using the tyres as prototypes with the Commencal Muc Off Team in the World Cup since 2022. Every time there was a D4 on the tyre sidewall, it was a tyre with a radial carcass. The contact area determines the amount of grip. The increased contact area therefore certainly played a decisive role in the extremely slippery conditions.

In addition to the E-MTB version, there will also be a slightly lighter trail version of the new tyres. For whom is this tyre the right choice?

We discussed the topic very critically. A pure E-MTB product was not enough for us. Even a classic mountain biker can definitely benefit greatly from it. Even with less mass on the part of the bike, great advantages are noticeable. If you were already riding a Schwalbe tyre with a trail casing, the new radial casing in the trail version is an option. For sufficient puncture protection, an apex in the radial tyre is mandatory for high puncture protection. This is why we only offer this technology for tyres with an apex. Ground or race tyres are not included.

"We initially prioritised lighter designs during development" - Carl Kämper, Schwalbe

Is it even possible to build really light tyres with this construction or are there stability problems?

The sidewall stiffness was our biggest concern at first. However, the first ride tests quickly showed that there was neither increased burping nor instability. On berms, it can just be a little unfamiliar because the radial tyre builds up a lot of grip. Lighter constructions were initially put on the back burner during development, but perhaps there will be exciting and innovative solutions in this area in the future. A flexible tyre has advantages for many off-road applications.

In a radial tyre, the threads of the carcass run at a 90 degree angle to the direction of travel. This is not quite the case with your new carcass. Why do the threads still have an angle?

We experimented a lot with the arrangement of the carcass threads, from 40 degrees upwards in five-degree increments. However, we do not communicate the final angle. We could only choose an angle so obtuse that the carcass would not lose its stability. The threads of the carcass plies must overlap. Since an additional fabric, as with our Snakeskin puncture protection, completely negates the flexible properties of the radial carcass, we had to come up with a replacement.

What does the future look like? Will all Schwalbe MTB tyres be rolling on radial casings in a few years or will it remain a niche? Will the additional radial carcass at least replace/replace existing carcasses?

We will certainly have more radial tyres in our range in the future. There is definitely still a lot of research and development required for light applications such as cross-country. However, new models are already planned for next year. So far, the radial carcasses are options for existing carcasses.