5 ultra-light carbon cross country wheels in laboratory and practical tests
Peter Nilges
· 22.11.2024
We tested the following wheels
Is aluminium the measure of all things?
Who would have thought it? Apart from the admittedly sluggish acceleration, there is no way around aluminium. The notes of our three test riders speak a clear language in favour of the much cheaper, but also significantly heavier reference wheelset with aluminium rims, at least when it comes to downhill handling. Good-natured, forgiving and cushioned are the attributes that the heavier aluminium wheelset earned in comparison to the carbon competition. The fact is, however, that cross-country races are won uphill. And this is where other virtues are important: low weight, stiffness, acceleration. In order to not only rely on the extensive laboratory data, but also to gather riding impressions off-road, we went on a meaningful test lap with six wheelsets and three test riders.
Without knowing the laboratory data in terms of stiffness and inertia, each rider had to note their personal riding impressions and create a sequence from soft to comfortable to stiff. The surprise: the practical impressions gained did not correspond 100 per cent with the lateral stiffness values determined. Although the stiffest wheels were narrowed down quite well, there were surprises with the softer models. The aluminium wheels that were perceived as very good-natured are actually very laterally stiff and the Newmen wheels with carbon spokes that were measured as soft in the laboratory were not perceived as spongy or imprecise on the trail by any rider. The measured lateral stiffness therefore only reflects part of the riding experience. And vertical compliance is also ruled out as a key parameter.
Even with a load of 200 kilos, a wheel only yields in the one-millimetre range. The differences between them are negligible. And yet there are noticeable peculiarities in the ride feel. In off-road terrain, other factors seem to have a decisive influence. For example, the rim and spoke material can have an effect on damping and vibration behaviour and result in good-natured or even stiff, unyielding behaviour in the overall structure. To reflect this effect, the ride feel is also included in the final score by 20 per cent. Nevertheless, lateral stiffness remains an important indicator that should not be neglected, depending on the rider's weight. After all, what suits a 65-kilo rider does not necessarily apply to a 95-kilo rider.
New materials such as the use of carbon or textile spokes, even in combination with wide rims, ensure record weights of well under 1200 grams. This ensures top acceleration. However, the tyres still have the greatest influence on acceleration. - Peter Nilges, BIKE Test Manager
This is how we tested
To get to the bottom of the quality of a wheel, BIKE relies on extensive laboratory tests. Our popometer in the practical test shows whether the interaction of the data obtained is right and thus the riding experience.
Blind test on the trail
Without knowing the laboratory values (stiffness, weight, inertia), three experienced testers rode all the wheels with standard tyres and identical air pressures on a selective circuit. The riding impressions gained regarding riding comfort, precision and general handling were incorporated into the final score by 20 per cent. Surprisingly, lateral stiffness alone is not always reflected in the riding impression
Impact test
In the impact test carried out by BIKE in the Newmen test laboratory, a 7.5-kilo round plastic cylinder hits a rim flange on one side at a 20-degree angle. The rear wheel, which is fixed to the hub, is tested in each case. Each new impact hits an intact spot on the rim. The impact energy/height is increased from 3.09 joules up to the defect. Our reference carbon rim (Newmen Phase Base), which weighs 93 grams more than the light version, shows the extreme impact of using just a few grams more carbon. Just like the extremely stable DT rim, it can withstand almost five times the impact intensity of the Newmen Light rim until it breaks. The picture below shows the damage pattern at drop height seven on our reference aluminium rim and the Bike Ahead carbon rim.
Inertia and weight
For an explosive start and efficient climbing, not only a low weight but also the distribution of the mass is of decisive importance. The further away the weight is from the hub, the greater the influence on the acceleration behaviour. On our test rig (Fig. 1) we can precisely determine the actual inertia of a wheelset. The two lightest wheelsets from Newmen and Pi Rope remain under 1200 grams and get going effortlessly. The Bike Ahead wheels with wide rims accelerate around 20 per cent slower. With the aluminium reference set, the difference is 35 percent. In combination with a mounted tyre, the difference between the wheelsets is relativised again. Due to the far outer mass of the tyre (e.g. 715 gram XC tyre), the gap between Pi Rope and Bike Ahead melts to seven percent.
Aluminium vs. carbon - the reference tests
To check how an aluminium wheel and a heavier carbon rim perform, we included two reference wheels in the test. The Newmen Beskar Light wheelset weighs 1680 grams and has aluminium rims, which also have a rim width of 30 millimetres. Compared to the lightest wheelset in this test, the aluminium wheels weigh more than 500 grams more, but only cost 680 euros.
The up to 35 per cent higher inertia is clearly noticeable when accelerating. In terms of lateral stiffness, the aluminium wheels achieve the second-highest value behind the Roval Control SL wheels. Nevertheless, the ride feel between these two wheels is fundamentally different. In the crash test, the aluminium wheels performed very well. At drop height eight, where four carbon rims already break, there is a clearly visible dent. At higher drop heights, the size of the dent and the deformation of the entire rim bed increase. The carbon rim, which is 93 grams heavier, ensures a 20 per cent higher inertia compared to the Newmen Phase Light rim. The lateral stiffness of the wheel increases by 15 per cent due to the heavier rim. The biggest surprise, however, is the impact test: The heavier rim can withstand five times the impact energy.
