![]() Roll is assumed to be an equal and opposite movement of the two wheels of an axle, this avoiding any philosophical debate/headache about around which point/axis the chassis rotates.Įach metric is anyway always referred to the “new” ground position, so if for example i input a roll movement, all will be calculated with respect to the ground now seating with an angle with respect to the global reference system.Īs the tool is still “work in progress”, it still doesn’t depict any of the components seating “above the control arms”, see for example the pushrod, rocker/bellcrank, spring/damper unit, antiroll bar and third elements. The approach i used, mainly for convenience, is to assume that the chassis remains fix with respect to the global reference system, while the floor moves with respect to it, either translating, rotating or both. The tool can currently calculate the result of each heave and roll movement and of any combination of the two. In my case, this point will only move in z (vertical direction), as this is all what we need to simulate how a suspension moves. Each moving point of a suspension is derived as the intersection of three spheres, with the center of each seating on an hardpoint whose position is fixed or has been already identified in a previous step the radius of the sphere is either a link length or the distance between the point we want to locate and another point of the same component (see for example a wishbone or the upright).įor the very first point (namely the outer point of the lower wishbone, in my case) we can use two close points (for example the two connection points of the same wishbone to the chassis) and a reference point, which can be placed everywhere and will be afterward used also as the input for each suspension movement. The method i used is based on the intersections of spheres in space. Since it is something i wanted to do since a long time, i really want to spend a few words about it here and, maybe, trace how it progresses.Īs the title of this post reveals, i am working on a simple suspension kinematics tool in excel, which is able to calculate the position of each hardpoint, basing on the defined suspension movement and all the most important metrics.įor now i am only focusing on double wishbones, as this is the scheme which is mostly used on the race cars i am interested in, but it should be pretty easy to adapt it to be used for a generic five links geometry, in the future. ![]() Altering offset will still affect the CoG of the bike, but much less than changing the ride height.This is just a short entry, to share a small project i am working on in the last few days. Sometimes it can be better to adjust the offset to achieve the desired result. You may adjust the ride height and get the rake and trail just how you want them, but in doing so you could completely screw up the bike’s centre of gravity in the process. The one thing to be mindful of when adjusting the ride height of your bike is the centre of gravity or CoG. And for newer riders, a slightly more predictable and stable bike would be more adequate. The longer you’ve ridden and the more track riding you’ve done – it’ll probably be at the racier, livelier end of the scale. Much of where you aim to land will come down to your riding experience. When setting up your bike you’re looking to find your place on this scale. Think about the handling of your bike as a scale with one end being the fastest turning machine on the road, and the other end is the epitome of stability and predictability. To decrease the trail of your bike – for faster turning and less stability – you would do the opposite of these steps. To increase the trail of your bike – for more stable handling – you can add a larger front tyre/wheel, raise the front ride height, lower the rear ride height, increase the rake angle or by decreasing the offset distance. As the yolk slides down the forks we can see how the rake and trail are altered. The (very crudely drawn) image above shows two bike chassis, the top as a more conservative set up, the bottom with a more extreme one.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |