PM: If there are any fractures or micro failures at the end of the test then that wheel doesn’t make it into production. That’s then sat on a one-metre diameter spinning drum which has twelve 7mm steel cobbles on it, and that is then spun at 25kph for 1,000km. The test wheel itself has a 23mm tyre on it pumped up to 120psi - essentially the narrowest tyre anybody is likely to use at the maximum pressure anybody is likely to use with a clincher, and because it’s directly loaded there’s no benefit of suspension through the frame or seatpost or saddle. PM: For a 100kg rider weight limit, which is our standard rider weight limit, we directly load 65kg onto the rear wheel at the axle.Ī rider’s weight is spread across two wheels but generally the weighting is 55 to 60 per cent on the rear wheel. So as well as real-world testing, we put our wheels through a rolling cobbled road test.ĬA: How does that rolling cobbled road test work? Because two of the key components of a wheel - the hub and rim - are made of aluminium, fatigue is one of the most likely causes of failure in a wheelset.Īluminium fatigues more easily than steel. PM: EN tests which replaced BSI tests are incredibly basic so dedicated wheel manufacturers like us have other tests we use. Materials scientist and director of Hunt Bike WheelsĬA: What tests do you run on your wheels? With a heavier rider they won’t fail within 100 miles or even 500 miles, but you might find that after 1,500 miles things aren’t as good as they should be and they will require extra care and maintenance.” Industry view: Peter Marchment To, to get a reasonable life expectancy out of that wheelset. “So rider weight limits are also an indication of what you need to adhere However, the added effect of fatigue over the years will be greater with the heavier rider. Wheels might have a rider weight limit of 110kg, but if somebody who is 115kg sits on a bike fitted with them, they won’t collapse. The nature of wheels and the way in which they’re used involves long-term cyclical loading. If you go above them you have to realise that you are taking on the responsibility for any failures. “But we think everybody should follow rider weight limits. He cycled Paris-Roubaix on our wheels, which was very cool but also a moment where we had to hold our breath a little! But it means we are as aware of heavier riders as anybody, and we know a lot of these riders come with a lot more power, too,” Tom said. One of the guys we have on our open development team is Will Johnson, who is a 17-stone ex-Leicester pro rugby player. “It’s not a problem, it’s an opportunity. Also, the increasing use of larger-volume tyres coming into effect now definitely reduces the overall fatigue on a wheelset.”Īnd what about those heavier riders - do wheel makers see them as a headache? “The limiting factor on a wheel is rider weight, whereas there are all sorts of other environmental factors regulating how strong you might want to make other components. A wheel is actually very well protected from any kind of unexpected forces,” Peter said. “It means that over the years the design of wheelsets has become optimised to be very competitive compared to other components, which can be used in different ways by different riders. You have two contact points at the dropouts and then one contact point with the road, and you know that all the forces will be loaded between those three points. “One of the things that is helpful when designing a wheelset is that, unlike most of the other components on a bike, the way in which forces are applied to a wheelset is quite predictable and well understood. > Seven essential things to look for when buying new wheels But we also have a range of different tests for different simulated rider weights,” Peter said. “We have a fair understanding of what rider weight a certain wheel build and spec can handle. If you wanted to build wheels that would provide the same characteristics for every rider, then you’d probably have to change the design for every five or 10kg of body weight,” Tom said.Īlthough we’ve been talking about stiffness and ride experience, Tom and Peter point out this is quite different to wheel strength and fatigue resistance. “So different riders at different weights will notice a difference in the way the same wheel feels to ride. But the 60kg Tour rider is looking for and will enjoy excellent stiffness from those wheels, while the 85kg rider will experience and might even want a little bit of give and comfort in that same wheelset. “Both riders could use that wheel - and this is why the wheels used by Tour de France riders are still OK for heavier non-Tour de France riders.
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