τauwerk delight
No ordinary bike.
A wheel that pushes the boundaries of what is possible.
A bike for those for whom only the best is good enough.
The aim of developing the tauwerk delight was to create the lightest wheelchair wheel in the world - paired with unique aesthetics and the best possible comfort. And without compromising on durability.
We have taken on each individual component and „rethought“ it using the most suitable materials and technologies.
#rims
After some searching for wheel rim manufacturers that meet our requirements in terms of expertise and manufacturing quality, we found the perfect partner for the development of outstanding carbon rims in the Austrian company Xentis®. The result of this development are rims that are unrivalled in the wheelchair sector when it comes to design, reliability and low weight.
The 28 mm high rim has an outer width of 25.4 mm. This harmonises visually and technically perfectly with the widely used 1“ (25.4 mm) wide tyres - for example the Schwalbe® One; Marathon or Rightrun.
However, the 17 mm inner width of the rim also allows for all other standard tyre widths between 20 mm and 37 mm. Two minimal elevations (so-called „humps“) in the rim base ensure the precise fit and concentricity of the tyres, even at low air pressures.
The rims are manufactured to 100 % in Austria in a predominantly manual process. The spoke seat areas are specially reinforced to ensure a permanently stable connection to the spokes.
Despite the very low rim weight of just 340 g with a diameter of 540 mm (24“), the rim has optimum stiffness and strength for everyday use. Each rim has a serial number and an RFID chip, which ensures complete traceability of origin and manufacture.
The valve bore has a diameter of 9 mm due to the manufacturing process and is reduced to 6.5 mm via an insert for use with hoses with a Sclaverand valve. It is possible to use tubes with a Schrader valve (car valve), but we recommend the more pressure-stable Sclaverand valves for technical and visual reasons. The rims are approved for a 1“ wide tyre up to a pressure of 10 bar.
#spokes
Our spokes are absolutely unique on the wheelchair wheel market. They are made from a high-strength synthetic fibre, which is five times stronger than steel. This enables us to produce extremely light spokes weighing just 2.4 g.
The fibre we use has good abrasion resistance and absorbs practically no moisture. Sensitivity to UV light is counteracted by a special coating and therefore no longer plays a role. The coating also significantly reduces sensitivity to dirt. The fibre has a high stiffness with practically negligible creep behaviour. It is therefore ideally suited for the spokes in a spoked wheel, which are subjected exclusively to tensile forces.
The fibre yarn is braided into ropes in our factory, which gives us the opportunity to produce patterns from different coloured yarns and thus create a unique look. The feel of braided and stretched ropes is also impressive and certainly unique. The ropes are then „heat-set“ under high load and temperature, which further improves their properties in terms of elongation and surface quality.
In further work steps, the cables are fitted by hand with non-detachable end connections made of high-strength aluminium and completed to form the finished spoke. The end connections enable the spoking and precise centring of the rim thanks to fine threads. The static tensile strength of our spokes is over 2000 newtons, which corresponds to a weight force of more than 200 kg. The tensile strength of the cable itself is even over 7000 newtons. As ropes cannot absorb bending moments per se, they deflect under lateral loads and return to their original shape after the load is removed. The increased tensile loads that briefly occur in the spoke are not a problem. Damage or permanent deformation of the spokes caused by impacting objects, as can occur with steel spokes - for example when loading the wheels into a vehicle - is therefore ruled out.
The biggest technical advantage over steel spokes, apart from the 65 % lower weight, is the inherent damping of the fibre material or the finished spoke. This damping noticeably increases riding comfort without requiring increased drive force. Especially on uneven roads, this guarantees fatigue-free riding even over longer distances.
1TP8Hubs
We use high-strength aluminium for our hubs, with which we can create minimalist hubs weighing significantly less than 100 g thanks to its lower density of 66 % compared to steel and sufficiently high strength.
The hubs are designed to optimally absorb and dissipate the external loads. The aim was to utilise the entire material to an evenly high degree, but at the same time to avoid areas with excessively high stresses. Modern design and simulation tools provided valuable support here.
Our paver's revolutionary surface blasting technology enables us to produce defined, absolutely uniform and 100% reproducible surfaces.
Any traces of machining are completely removed, giving the hubs a superior look and feel. In addition, blasting further increases the strength of the areas close to the surface.
1TP8bearing
We only use high-quality ceramic bearings in our tauwerk wheels. Ceramic bearings, with their very hard and extremely wear-resistant rolling elements made of silicon nitride, offer significantly lower friction and an unrivalled service life compared to standard ball bearings with steel balls.
Ceramic bearings, such as those from ceramicspeed®, which are handmade in Denmark, have been proven to run more smoothly and are also lighter. They offer a five to ten times longer service life than standard bearings - even under high loads. We think there is no reason to install other bearings in the tauwerk delight.
Our wheels are available for axle diameters of 12 mm and 12.7 mm (1/2 inch). The bearing distance is 56 mm (outer/outer).
1TP8pinch tyres
The push rims are bolted axially to the rim at six points. This type of mounting gives us a much more appealing, organic overall design than with the usual protruding and bent push rims. However, this variant also offers advantages in terms of strength, installation effort, push rim positioning and risk of injury compared to the mounting method with lugs.
The distance between the handrims and the rim is set neatly using spacer sleeves and can be easily adjusted to individual requirements at any time - even with the tyres fitted. All wheels are supplied with corresponding spacers made of anodised aluminium. The bolt-on points on the rim consist of form-fit, captive inserts made of the same aluminium and ensure a stable flow of force between the push rim and wheel. We only use titanium bolts for the best possible compromise between strength and low weight.
We only use high-quality, lightweight push rims from Carbolife®. These are also „made in Germany“ and, thanks to their innovative ergonomic profile shape, ensure an effortless, controlled and fatigue-free grip. The push rims are available in different versions.
1TP8Spoking, 1TP8Centring and #apping
Each tauwerk wheel is carefully spoked by hand in our workshop, centred and pressed several times during this process. The spoke tensions of all spokes and the concentricity and axial run-out of the rim are recorded and documented electronically for each wheel. The repeated, defined bead breaking permanently prevents the tauwerk wheels from having to be (re-)centred when used properly.
Tauwerk wheels are radially spoked, i.e. the spokes do not cross and run on the shortest possible path from the rim to the hub. This maximises wheel rigidity in the transverse direction while minimising overall weight. Crossed spoking, as is usually found on bicycle wheels, is not necessary for wheelchair wheels, as no torques need to be transmitted between the hub and rim in the direction of travel. In contrast to bicycles, the drive and braking forces on the wheelchair are transmitted directly to the rim via the push rim and do not first act on the hub. Contrary to popular belief, crossed spoking does not result in increased rigidity or stability under wheelchair loads.
The oval spokes are aligned in the direction of travel, resulting in an even and dynamic look, similar to the so-called „knife spokes“ in the bicycle sector.
We centre all wheels with a lateral and radial run-out tolerance of +/- 0.2 mm and a spoke tension that is as uniform and high as possible on each side. This ensures that the wheel can permanently withstand the loads acting during operation without individual spokes losing their tension for a short time - and thus coming loose - or being overloaded.
The wheels are pressed down by hand several times during this process. This prevents further setting of the spokes during operation and the associated uneven running.