FAQ: What’s the best swingarm design?

The general consensus is that twin-sided swingarms are inherently more rigid in their design than single-sided swingarms, but is it something you’d really notice in day-to-day riding on the road? Let’s check out the facts.

Single-sided swingarms
Single-sided swingarms came to the fore in the late 1980s with Honda’s VFR750R RC30. This was a race bike for the road, and it was a hugely successful machine. Shortly after, a very similar design became available on the regular road-going VFR750F, bringing single-sided trickery to the masses. Honda has stayed true to the cause since then, and still offers a single-sided swingarm on a number of its machines.

Ducati did its own version on the 916, and the current Panigale still sports a single-sided rear setup. BMW has been on the single game for years, for both on- and off-road models, and KTM’s Super Duke naked has one as well. Triumph’s Speed Triple has sported one for years now, also.

Other manufacturers have tried them before, nearly 100 years ago in the early days of two-wheeled motorised transport, but it took until the 1980s for the technology to catch up to alloy designers to make reliable versions.

Looks do matter
Aesthetically, there’s not much to top a single-sided swingarm. No doubt the marketing positives of such a design is a major reason for manufacturers to introduce them. They are more complex and expensive to make and are heavier than regular twin-sided swingarms, but how many VFR750 Hondas have been sold on the basis of an easy to remove rear wheel? Lots we would think…

Racing has long been an area where manufacturers push design boundaries and. The Honda RC30 was built to race, especially on the endurance scene, so rapid rear wheel changes were big news. To be able to race the RC30, Honda had to build enough road versions to the public. Once this was achieved it wasn’t a big stretch to bring it out on the regular road VFR750. The rest is history.

There are many forces acting on a motorcycle’s rear wheel, which is the reason a single-sided swingarm from just about any manufacturer is as substantial as it is. They need to be thicker, stronger and just plain bigger than a double-sided unit. You simply could not make a single-sided one out of the same thin-walled material as a double-sided job and expect it to perform the same.

Design parameters
So they look great, but what about serviceability and handling. On the handling side, most riders, if any, would never notice the difference. On the track, most probably wouldn’t either. Ducati has run them for years in world superbike competition, so the design isn’t flawed. But here’s a kicker for anoraks.

Back in the early Ducati 916 days, fabled US based race outfit Fast By Ferracci replaced a 916’s single swingarm with a custom double-sided one, declaring it was better for racing because the original setup dictated the fitment of a flawed exhaust system. Fast By Ferracci’s custom double allowed a better exhaust. It might have worked but it didn’t last long, as from then on Fast By Ferracci went back to the original 916 setup. Too hard, maybe?

For maintenance, the single-sided swingarm is easy to live with. Tyre changes are a snack (yes, you will need a special wheel nut for most brands), and instead of sweating and swearing while you’re trying to line up rear calipers and axle spacers on your double-sided rig, the single-sided rider is already riding down the road. Chain alignment is easy too, as it’s usually done via an eccentric adjuster on the end of the swingarm. It’s usually as easy as undoing a couple of nuts and using the right C spanner to rotate to eccentric adjuster in the direction you need. There’s no lining up the rear wheel, it stays a constant in the whole affair. Now there is a downside to this – but only if previous owners had overlooked maintenance.

The eccentric adjuster at the rear of the swingarm can seize and be a royal pain to move, necessitating the removal of the rotating assembly at the rear of the swingarm. Time consuming and costly.

Double-sided swingarms
Double-sided swingarms have been the dominant force over the years. They are cheaper to make, are lighter and do the job admirably. But the design has also changed markedly over the years. While some entry-level motorcycles have cheap and cheerful, thin-walled steel swingarms holding the rear wheel and suspension to the bike, high-end sportsbikes have things of substantial beauty doing the same job.

In the late 1970s, a number of aftermarket swingarm manufacturers made trick-looking braced swingarms for the larger capacity Japanese motorcycles of the time, as the standard ones just did not cut it. The manufacturers got the idea eventually, and most aftermarket swingarm makers went the way of the Dodo.

Top bracing, under-slung bracing, gull-arm, banana, tubular steel, alloy, double-sided swingarms just got better and better.

The main advantage of the double-sided swingarm is its rigidity, and the relatively simple manufacturing process. Yes it’s harder to get the rear wheel off, and chain adjustment and alignment is slightly more involved, but it doesn’t have a heap of weight to one side of the bike like a single arm has either.

Does length matter?
The length of a swingarm has a massive impact on the way a bike handles, and in most cases, manufacturers will design the bike to suit most conditions their perceived rider will encounter. Even high-end sports bikes have some compromise factored in so they are not some flighty beast on the road for example.

Swingarm length and pivot position in relation to the front sprocket has long been a headache for designers. This is a major area which determines how a bike handles, how it turns into corners and how it squats, or doesn’t, under acceleration.

Generally speaking, a shorter swingarm will shorten the wheelbase and make it handle ‘quicker’, a longer one does the opposite making it more stable. But you can’t just plonk a longer swingarm onto your road racer without contemplating how it will affect the front end. It’s relatively common to see racers change the offset of their triple clamps, which affects the trail positively for the track, and then to compensate with a longer swingarm to reduce rear suspension squat and keep the front end on the deck and tracking straight, making for a sweeter handling and steering bike than before.

For the vast majority of riders it all comes down to personal preference of the styling and maintenance rather than any real benefit in road holding, if both are well maintained.

Personally I love the single-sided swingarm. Factory trick, and factory slick wheel changes are the life for me.