The ergonomic triangle.
Ergonomics experts describe the human-machine interfaces on a motorcycle as an ergonomic triangle. The interfaces are obvious, they are the places where the human being has direct physical contact with the machine, his motorcycle. These places are the handlebars, the seat and the footrests.
The aim of ergonomics on the motorcycle is to create facilities whose optimal spatial arrangement allows relaxed and fatigue-free riding.
At Wunderlich, we have been working on improving the ergonomics of BMW motorcycles for over two decades. There are three basic components for customising a motorcycle.
Basic components of motorcycle ergonomics
If you want to fundamentally adapt your motorcycle with regard to ergonomics, we recommend that you consider three components:
- Our seats
- Our handlebar risers
- Our footrest systems
Dr. Ricardo Wunderlich.
Experienced doctor and passionate rider
As Erich Wunderlich's brother, Dr. Ricardo Wunderlich accompanies almost all developments, especially those that touch on ergonomics, with his expertise as a doctor and chiropractor. And this has been the case for many years. But he brings with him another quality that is indispensable for us: like his brother, he has been a passionate motorcyclist since his youth, and is thus called to combine and contribute his knowledge and experience from both fields, medicine and motorcycling. Here, he has summarised his thoughts on the ergonomics triangle.
»My name is Ricardo Wunderlich and I have been a general practitioner and chiropractor for 25 years and an enthusiastic moped and motorcycle rider and mechanic since I was 13 years old, i.e. for 45 years. As I am currently taking some time off work, I was happy to accept the request to help develop the ergonomics concept at Wunderlich. Arno Gabel from Wunderlich GmbH has already summed up what we all suspected from the beginning of our riding. The ergonomics triangle.
We are phylogenetically descended from apes. You would think that a person would feel most comfortable sitting with their shoulders slumped. However, the sitting posture on the motorcycle is more akin to that of an ape and therefore not uncomfortable. The seat is comparable to a skier's ski boots. It has to fit perfectly and you simply can't skimp on it. Some think a customised seat is the better way to go. But it's like roulette. It can go well. If not, you have no chance to return it, and actually you only know after a few 100 km whether it went well.
At Wunderlich, we dedicate ourselves to the problem of ergonomics, a subject that has always been neglected by motorcycle manufacturers. This belongs in the hands of motorcyclists who are part-time mechanics, designers, upholsterers, doctors, CAD programmers and engineers.
From my medical-orthopaedic point of view, the design of the ergonomic triangle is as follows. I am now speaking only for street motorbikes. A racing motorbike serves its purpose, but it doesn't have much to do with ergonomics and is more suitable for men with a height of 1.60 m and a muscular build. A sports bike also needs power and, in my eyes, only looks fast. With a comfortable seating posture, you can be just as fast if you don't have to go over 140 km/h. And a comfortable sitting posture is also what I would recommend as a medical professional. When nothing disturbs and everything fits, you can concentrate completely on the road. This includes a reasonable distance between the steering grips and the shoulders, a comfortable offset angle of the hands, i.e. slightly abducted. The flexion of the thighs relative to the trunk and the lower legs to the thighs should be slightly less than 90 degrees. Unfortunately, it is very fashionable nowadays to always stand with the tips of your toes or the balls of your forefeet on the rests. Actually, the most comfortable way to stand is on the arch of the foot, just like motocross and trial riders do. You should only stand with your toes on the footrests as soon as you come to a bend. Otherwise, you drag your outer instep or toe on the ground.
The first and most important thing is the seat, as already mentioned. The height of the chosen motorcycle must not exceed the height at which both heels can easily touch the ground. It must be curved on the flanks so that you feel comfortable standing. When sitting, it should have a good grip and a longitudinal depression in the middle so that the rider does not feel any unpleasant shearing forces in the genital area during longitudinal acceleration and deceleration (i.e. they don't slide around uncomfortably on their nether regions when accelerating and braking). When sitting, the ischial tuberosities transfer the body mass to the seat. Less so the gluteal muscles. The coccyx should be completely spared. This would also be mechanically stressed when bumping into the edge of the passenger area, which is unpleasant. That is why the rider's area of the seat must be generous in the longitudinal direction, also to give the rider freedom of movement. When riding solo and when we're really in the flow, we move around a lot on the bike. Both in a transverse and longitudinal direction. Even if we don't slide around on the seat in traffic, we do tilt our upper body forwards, backwards and sideways, so we roll around with our buttocks on the seat and simply need space for this. The passenger seat is a little smaller to accommodate this. That's not so bad, though, because you don't bounce around like that when you're riding pillion. But that is another topic. What is very important for both, pillion and rider, however, is a forward rise of the seat, so that you don't have to lean forward so much when braking. All these requirements are taken into account by the specific 3D contour of our AKTIVKOMFORT seats. And this is regardless of whether it is the standard height or the lower or higher version of the seat.
We could go into all these topics in greater depth, which is also what we are doing in our company. The bottom line: it is possible to build a seat that feels good for almost all riders!
And if the seat height is right and the seat is comfortable, look for the most suitable handlebars or whether they need to be raised or moved back. The third thing to look at is the position of the footrests. Last but not least, there is the exact position of the gear-shifter, the length of the hand levers and their distance from the handlebars.
Of course, it would be perfect if you could enter your bike, height, weight, stride length and, if you like, your arm length into a computer programme and it would calculate the optimum equipment. We're working on it!«