Pinkbike, the first global community and the largest reference in mountain biking, called on the services of Creaform to perform suspension analyzes for users and enthusiasts around the world. Their latest “Behind the Numbers” blog post series, powered by engineer and cyclist Dan Roberts, is dedicated to in-depth analyzes of various suspensions.
Amidst the abundance of technical information and product data, blog contributors were looking for new technologies to analyze short-link ATVs (such as the Santa Cruz Megatower) , more efficiently and quickly (eg, measuring suspension curves, angle of the stem, lower fork height, boom, etc.). It was then that Dan Roberts, based in Switzerland, contacted our company, which develops, produces and markets metrology instruments, such as 3D scanners and reverse engineering software.
While the geographic distance might have been reason enough to end the adventure between Creaform and Pinkbike, for Dan and his geeky nature, the decision was already made. The project could therefore continue, to the greatest interest of mountain biking enthusiasts with a taste for technique and precise data.
We will present to you below the metrology project which made it possible to obtain exact measurements and reliable data for all cycling enthusiasts.
Since the linkage defines the position of the center at all times, even the smallest changes in the pivot points of short link geometry bikes can have a big influence on the behavior of the bike. The team sums it up this way: “Before getting our hands on the Megatower, we analyzed bikes with relatively large connections. And our degree of accuracy in the measurements was more than sufficient for these configurations ”.
Creaform was excited to support Dan Roberts in his goal of making rich and accurate suspension data and figures available to all fans who take cycling seriously. In the metrology industry, we offer particularly fast scanning instruments. Not only do our tools allow for quick preparation and scanning without surface preparation, but the time required to place targets before you can finally handle the scanner is also very short.
Thus, the team sought to procure a Santa Cruz Megatower to perform analyzes. As luck would have it, the Mathieu Performance bike store in Quebec City (a few kilometers from the Creaform headquarters) had this model available in its stocks.
The Creaform team could get down to business: go to the store in question, measure the pivot points, axles and tubes of the fork and seat, in order to extract their geometries. In doing so, the portability of the scanner has proven to be a valuable asset. Creaform was therefore a particularly suitable partner for this mission.
The use of 3D scanning technologies for this project also made it possible to accurately capture volumetric positioning and the solution provided 0.1mm accuracy on distances from one end of the bike to the other. We were far from imagining that this precision was more than sufficient for analyzes, with even greater fineness compared to the tolerances used for manufacturing in the cycling industry.
1. Quick preparation and creation of a repository framework
The installation of the equipment for this project, as for any other project, did not require any rigid, fixed and / or bulky equipment: the bike was placed in front of a cardboard box on which the team applied positioning targets.
Positioning targets are reflective stickers used to create a frame of reference to allow the 3D scanner to automatically position itself in space. They can be placed on the scanned object or within its immediate environment. In order to ensure optimal tracking, we had to use a few additional targets.
In order to generate a mesh, the scanner had to detect at least three targets at all times in its field of view, but since the geometry and the volume of material of a bicycle are usually irregular, we had to place a cardboard box in the background of the bike to place more targets.
The HandySCAN 3D has a field of view of approximately 30 by 35 cm, which means that the targets should have a distance of approximately 5 to 15 cm between them, placed randomly. In this case, they were placed relatively close to each other, both on the map box and the bike itself, since some components of the scanned object had complex geometries, distinct characteristics and many textures.
Basically, regardless of the overall complexity of the task, Creaform's portable 3D scanners make it easy to take measurements quickly and easily, on small and large objects, in the workshop and even in the backroom. from a bike shop!
2. Redefining accuracy in scanning mountain bike suspensions
Creaform's HandySCAN 3D, used for the suspension analysis of a short link mountain bike, achieved a local accuracy of 0.025mm. This means that scanning the bike done with the HandySCAN 3D revealed the smallest variations between concept tolerances and manufacturer specifications, compared to the bike itself. In other applications, such as quality control during bicycle manufacture, such a level of accuracy is not only enviable, but also desirable!
3. Mesh: Calculation, creation, processing
The output format of digitized surfaces is known as a mesh or mesh file. It takes the name of what virtually looks like a 3D rendering of an object: a kind of woven net or wire mesh made up of millions of small triangular surfaces. For this project, we used a triangle size of 0.35mm to capture the detail of the features we needed to extract, but decimated the mesh (i.e. we created more triangles large on the flat areas and kept the small triangles on the detailed areas). The HandySCAN 3D can provide a blank mesh surface with 0.1mm minimum triangles, which made it possible to create the bike surfaces regardless of their complexity. Zooming in on the components can be quite revealing: the number of triangles that make up the mesh varies depending on the level of detail needed and the area scanned. You can refer to the visual below to observe the level of detail captured by the scanner.
Live meshing is a particularly useful feature of Creaform solutions. As the user scans the actual object, the exact data captured can be observed in the VXelements software interface. This provides an STL file for easy use in CAD software. Thus, the user can instantly view on a surface where a feature does not appear during the scanning process.
Logically enough, the scan file can turn out to be quite large, so getting a decimated version should be done to speed up the overall process.
In this case, the main things to capture were the pivot points, axles, fork tubes and seat post. In the end, the data captured from the extracted points would allow the geometry and kinematics of the bike to be displayed.
It might seem like a lot of work to get a 2D sketch of the bike, but it is a very quick process and the accuracy achieved is so high that we could look at the tolerances of the individual parts of the bike.
4. Output format and export to CAD software
To finalize the digitization process, geometric entities, such as the pivot point, can be imported directly to the preferred CAD software in use, using the VXmodel software module, proprietary to Creaform. It integrates seamlessly with VXelements and thus allows finalizing 3D scan data. While CAD software comes with all the design and modeling capabilities you need, VXmodel provides the tools to quickly and seamlessly integrate a scan-based design process.
Features and benefits: precise, fast, versatile, portable, no surface preparation
The Behind the Numbers series of banknotes would not be as reliable if the numbers presented were not as accurate. Creaform provided Dan Robert with the means (halfway around the world!) To precisely measure data the team was struggling to describe: short-link suspensions.
Now in possession of these figures, Dan Robert performed in-depth kinematics analyzes of the short link bikes, in order to determine the actual values regarding the leverage ratio, anti-sag, anti-derailment, travel of the axis, etc.
The digitization took about 15 minutes and the entire process from preparation to the final 3D model took less than an hour.
Looking back, we can assure readers that readers can trust the Behind The Numbers series of posts, as contributors have made every effort to ensure that all measurements are correct for all bikes and setups.
In the end, this joint adventure made it possible to provide exact data concerning the short link suspensions, in order to pave the way for methods of positioning the pivot points, in a finer way than what was expected during the stage of design. In reality, they have barely scratched the surface of what is possible with 3D scanning in the ATV industry.
Manufacturers in all industries who have not already tried or implemented it can take advantage of 3D scanning technologies to validate concepts, inspect and compare components, as well as create intelligent product designs.
Pinkbike and Creaform wish to send their thanks to Santa Cruz, for their openness to discussion and their efforts in their quest for accuracy and consistency. We would also like to thank the Mathieu Performance bike store in Quebec, which opened its doors to us to play with their Santa Cruz Megatower, as part of this project. Finally, a big thank you to Dan Robert, the instigator of the Behind the Numbers article, which illustrates Creaform's 3D scanning technologies. Former senior bicycle engineer at Scott Sports, Dan Robert created the Garage Bike project, engineering services for the bicycle industry, based in Champéry, Switzerland.
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