With years of testing knowledge on full wheel systems through Rolf Prima, Astral™ has access to in-house testing that many in the industry only pretend they have. We start with CAD models analyzed in FEA (Finite Element Analysis) to find and optimize high-stress points. When we are satisfied, for alloy we move on to prototyping with our extrusion or mold vendor and begin the iterative improvement process. We subject our rims to a rigorous series of tests standardized by both ISO and the UCI, but primarily our own, much more strenuous tests.
Our philosophy is that if you are doing anything interesting, you are going to fail on your first shot. Maybe your second. It’s like riding the harder lines and bigger drops. You just need to stick with it, hold on and work it out. Not infrequently, a rim does not pass all hoops we set in front of it on the first go-around and we analyze results, think, sketch, revise and start the next prototyping round.
Fatigue Drum Tester
Field testing is great and necessary, but let’s face it — it can be slower to turn up the issues you want to find. What if you could simulate the rigors of use on the road or on the trail in a shorter period of time and in a controlled environment? That’s exactly what our fatigue drum tester does. With this machine, we can put thousands of bumpy miles on our rims in a matter of days all while keeping a close eye on the process from start to finish.
Our fatigue tester is based on the ISO4210 test, but both our method and our requirement are far more stringent. Where ISO runs at 15 mph, we run at 47mph imparting over 3x the energy into the wheel than the ISO standard. Our requirement for how long a wheel lasts is also 66% higher than the ISO standard. What does this mean for you? A bomber rim.
Brake Heat Testing
Starting with top-shelf materials in a carbon rim and using a resin matrix designed for the high temperatures of braking is just step one. Verifying that it is what you expect is step two. Optimizing the system to decrease the heat is the final step. Having access to the facilities and data acquisition systems in-house enables us to pinpoint hotspots and their causes and iteratively work on tweaks to improve. And then repeat the process.
Whether it is in a paceline or a rock underneath the leaves, we know you are going to hit something. Our impact testing is multi-faceted. We perform the standard required tests including the UCI test but we also test to a higher, harder standard. This is to make sure our rims can take the abuse we (and you) put into them.
Impacts also do not happen in a vacuum. What happens if you’ve been braking a lot on your carbon clinchers and then you drill the pothole? We cover that too. We heat our rims up and then impact them to ensure we have covered all the bases.
There is a lot of commentary about the importance of stiffness to how a wheel rides as well as to what changes stiffness. There are a number of factors that affect a wheel’s stiffness and not all of it is lateral. Some of it is the rim and some are from other components. Our stiffness testing regime has several components - some rim only and some of the complete wheels. Our stiffness tester allows us to combine loads in multiple directions to detail how a rim or wheel will behave in various loading configurations. This allows us to modify rim profiles and other factors to improve how a wheel will ride and behave.
Lateral stiffness comes into play because it affects how a wheel rides - any wheel with any number of spokes. Having good lateral stiffness can mean the difference between whether a wheel feels snappy or a wheel feels spongy. It is not the whole story, but it is an important piece of it.
Our lateral stiffness tester allows us to measure a rim’s stiffness in a continuous way, so we can see how the rim behaves under a lateral load as the geometry of the wheel changes with deflection. We can slowly apply lateral force to a rim and measure how much load it takes to deflect the wheel over lateral distance.
We begin by measuring the initial location of the rim on the fixture then applying a small preload to eliminate any slack in the system. We gradually apply a lateral force working up to our maximum load. Once reached, we hold that load on the rim for 60 seconds. The load is then released and the rim’s location is measured again, comparing it to the initial measurement. We also check trueness. We can use the same fixture for lateral strength testing. This is an overload test where we measure how much lateral force a rim can absorb.