Let us talk a bit about the single sided swingarm, especially considering a video that went viral recently.
The footage showed a rider and his pillion on a bike when the pillion suddenly became agitated. The camera then panned right to show their bike’s rear wheel running next to the divider and overtaking them. It concluded with a Ducati Hypermotard on its side sans the rear wheel.
Netizens were quick to provide their own comments of the incident. Some were just pure banter, some were jokes, some were derision, some were er… post-mortems.
One such comment in our sister site, MotoMalaya attracted our attention. The commenter said, “That’s the disadvantage of the single sided swingarm.” The comment was followed by plenty of derision.
Like it or not, that comment has some truth. However, before we proceed further, we would like to state that such occurrence is very rare. And it is not only Ducatis that are fitted with single sided swingarms as several other manufacturers do so, too. For example, BMW, Honda, Moto Guzzi, KTM, CFMoto, MV Agusta, Triumph, and of course scooters!
The main advantage of the single sided swingarm
The primary advantage of the single sided swingarm is quick and easy rear wheel removal and installation. Remove the tightening nut or bolts and out comes the entire wheel without upsetting the chain tension and rear brake as the rear sprocket, brake disc, and brake caliper are mounted on a carrier.
There is a very short and stout axle to hold the wheel in place. Thus, one only needs to reinstall the rear wheel and retighten the locking nut or bolts and not bother with chain tension and axle alignment.
In fact, this was why Massimo Tamburini designed the seminal Ducati 916 with a single sided swingarm. It was thought that Ducati had wanted to enter the 916 in endurance races. Tamburini himself said that he drew inspiration from the Honda NR750. Other contemporary rivals were the Honda RC30 and later RC45 – both also sported single sided swingarms because they were raced in endurance events.
However, Tamburini did also mention that aesthetically, the rear wheel appears as if it is floating and not connected to the bike. It then became the signature of high performance Ducatis and continues to be used until today.
The double sided swingarm, on the other hand…
Conversely, a double sided swingarm requires an axle/spindle to be inserted through the center of the wheel to connect both sides.
One needs to pull the axle out, take the chain off the sprocket, and pull the brake disc away from the caliper.
The drive chain requires tensioning and the entire rear end needs realignment when the axle and wheel are reinstalled. The tensioning and alignment process needs time and care. An improperly aligned rear axle will result in abnormal tyre, chain, and brake pad wear, besides handling issues.
But should the lock nut break loose and depending on the design of the rear of the swing arm, the chain can hold the axle in place albeit misaligned. Similarly, the brake caliper bracket or holder helps to keep the axle and wheel from sliding out.
Then again, there are incidents where the rear wheel came off double sided swingarms. Point is, it takes a longer time for the rear wheel to slide out and there will be plenty of warning symptoms if the axle nut was improperly tightened or had come off, such as the rear of the bike pulling to one side.
In a nutshell
So, is a single side swingarm inherently dangerous?
All engineering practices consist of compromises. That is why the rear wheel is locked with a large nut and pin or several bolts. Therefore, the proper tightening torque is essential, so use a torque wrench, for crying out loud!
We would like to state again that this was a very uncommon incident. In any case, always inspect your bike before riding.
