A Quick-Change Wheel Concept, Long Overdue

Yamaha’s MORPHO concept incorporated several innovative features.

yamaha morpho concept
Ease of use was key to the MORPHO’s design. The entire cockpit and rider triangle was highly adjustable.©Motorcyclist

Recently, a photo of the Graves Racing Yamaha superbike caught my attention. It showed the bike on a workstand in the pits with the rear wheel removed but the sprocket and chain still in place. Was I looking at some innovative quick-change rear axle setup that allowed the sprocket and chain to stay put while the rear wheel was removed?

I wasn’t. The sprocket and cush-drive hub was simply slipped back in place on the axle to keep everything tidy while the wheel was off. No new invention here. But the possibility that this was some novel quick-change setup took me straight back to 1988, when I was involved in discussions with Yamaha concerning my RADD front suspension that would eventually appear on the Yamaha GTS1000. I had also shown Yamaha some ideas that I’d decided not to patent, and a quick-change rear wheel was one of those ideas.

A year later, Yamaha debuted an innovative concept bike called the MORPHO at the Tokyo Motor Show. Ergonomic adjustability gave the bike its name—it could "morph" into different riding positions—and at the front end it used a suspension looking much like my RADD system but with a different (and ultimately unworkable) steering arrangement.

The rear end featured my quick-change rear-wheel setup, with a sprocket, chain, and brake disc that all remained undisturbed when the wheel came off. Yamaha had decided that the single-sided swingarm was Honda’s exclusive territory—Honda then used single-sided swingarms on a few different models, all based on technology from the French ELF racebikes—and it was looking for ways to incorporate the advantages of a single-sided arm on a traditional, dual-sided setup.

My idea, as it appeared on the MORPHO, positioned the disc and sprocket close together on the left side, all held in place by a short, hollow, large-diameter stub axle. A conventional axle that passed through the stub axle held the wheel itself. Pulling the wheel axle out allowed the wheel to be removed while the disc, sprocket, and chain remained in place and in adjustment.

The MORPHO quick-change assembly never appeared on a production bike, but this wasn’t the end of the story. Yamaha adapted the system for endurance racing bikes in the early 1990s, and the bikes raced at Suzuka and other World Endurance Championship events around the world utilized a spin-off of the MORPHO system. In this application the brake disc was located outside the sprocket, on the left side, so that a smaller disc could be used while still retaining standard, non-offset (center-spoked) racing wheels.

As conventional quick-change setups for racing improved and allowed ever quicker wheel swaps, specialized options like single-sided swingarms and the Yamaha system based on my idea became less necessary in endurance racing. But my thinking is that everyday motorcyclists need something like the quick-change system I came up with in 1988 just as much now as we did back then. Who likes messing with a dirty chain just to pull off the rear wheel? Who likes aiming the brake disc into that small slot between the brake pads as the wheel goes back in? Who hasn’t heard of someone accidentally hitting the rear brake pedal when the wheel was off and then having to lever the pads back out? Maybe there are a few masochists who enjoy these exercises, but I’ve never met one.

Imagine having to detach both the drive and brake mechanisms to change the tire on your car or truck. This is what we do on most bikes. Given the choice, I prefer a true single-sided rear swingarm, but if we need to have two-sided arms, we should at least have a system that allows the chain and brake to remain in place. Innovation doesn’t always mean performance. Sometimes it can mean something as simple as convenience. What a concept that is.

James Parker designed his first original motorcycle in 1971; his most recent design is the Mission R electric superbike. In between, he worked on multiple other motorcycle projects, including 30 years spent evolving the RADD front suspension system used on the Yamaha GTS1000 and various other prototypes.