Why and How We Measure Motorcycle Ergonomics

When I came to Motorcyclist the first time in late 1999, it seemed we could do a better job of describing what made one bike comfortable and another not. Beyond, of course, the subjective assessments so strongly influenced by personal preference and body shape. Certainly there was a way to measure the elements that make up the riding position so we could compare bikes objectively as well as subjectively. Occasionally, manufacturers would include an illustration that defined the seat, handgrip, and footpeg locations on a profile view of the bike. Great! But few of the OEs provided actual measurements, making brand-to-brand comparisons impossible.

Why couldn’t we do that? We could, but it took some thought before a method emerged. Locating the contact surface of the footpegs and handgrips was relatively easy. But how do we decide where to take the seat measurement? There are so many varieties of seats, and you sit differently on a sportbike than you do on a cruiser. Feeling that simplicity was best, we came up with a pair of instruments, one meant to butt up against the fuel tank for sportbikes and another meant to snuggle into the rearmost portion of the seat pocket on cruisers and tourers. Place the tool on the seat and start your measurements from there.

Of course the fixed measuring points are a compromise. One sportbike might have a longer saddle than another, and so the way you sit on them might be a little different. We thought briefly about mapping the seat area and picking an arbitrary center point, but some testing with then-current bikes proved that the variation was acceptably small. I briefly had fantasies of buying a Faro arm or seeking another way of electronically measuring key points on the bike. And talks started with Computrack to adapt its theodolite-based system, but the time it would take to measure each bike seemed prohibitive.

We ended up with simple-to-take key measurements that helped define the way a bike “sits.” First is the seat-to-handlebar measurement (A), taken in a straight line from the plane of the seat to the handgrips. Trying to define a point above that plane useful to the discussion would involve looking at various body shapes to determine the torso/shoulder point, so we went with the simpler solution. Next was the seat-to-footpeg measurement (B). By also measuring the distance from the pegs to the handgrips we can calculate something called the included seating angle (D), basically how “open” or “closed” it is. A greater angle means either rearset footpegs or a taller handlebar or both.

Because the handgrips’ height above the seating plane also influences your body angle, we take a pair of measurements—from the seat to our reference plane (currently, our Discount Ramps lift) and another from the grips to the plane. Math gives us effective handlebar rise (C). All bikes are measured leveled longitudinally and vertically, unladen, and on stock or as-delivered suspension settings. We measure both sides of the bike and average for a result.

Yes, there are quirks in the system. For example, bikes with really tall bars can seem to have a long seat-to-grip distance, when the horizontal distance from the seat to the bar clamps is moderate. That’s why we also include rise and seating angle (and why we place these numbers over a photo of the bike, for context).

Not perfect, but the system has worked well over the years, and it’s interesting to look through the data to see the changes. Example: Yamaha has been making the YZF-R1 more aggressive each generation, with almost half an inch less bar rise in 2015 compared to the 2006 model, the seat-to-bar distance has increased more than an inch, and legroom is tighter. So when we say the new bike is less comfortable than R1s we can remember, it’s not just our subjective impressions.