Original image by Rich Niewiroski Jr., CC BY 2.5, via Wikimedia Commons
In addition to a shock absorber, your motorcycle or scooter’s rear suspension also consists of something called a “swingarm.”
It may not seem like it’s important, but it is.
In this blog post, you’ll discover:
- What the swing arm is, and where to find it
- Differences between single vs. double-sided swingarms
- Why some motorcycles still have double-sided swingarms
What Is The Swing Arm On A Motorcycle?
The original uploader was Jeff dean at English Wikipedia.Later versions were uploaded by Motorrad-67 at en.wikipedia., Attribution, via Wikimedia Commons
A swingarm (also known as a “swinging arm” in the UK) is a movable joint shaped like the letter “L” or “H” that’s part of the suspension setup.
If your motorcycle had no swingarm, there would be no support for the rear suspension – or the rear wheel, for that matter.
Where is the swing arm located?
You’ll find the swing arm at the back of the motorcycle. One end is attached to the rear wheel, while the other end is attached to the main frame through the “swingarm pivot bolt.”
On a motorcycle with shaft drive, the housing for the shaft acts as a swingarm.
Either way, this swingarm pivot bolt makes it possible for the rear wheel to move up and down.
Single vs. Double Sided Swing Arms
At a fundamental level, motorcycles and scooters with just one swingarm have a “single-sided swingarm” setup.
Meanwhile, ones with two swingarms have a “double-sided swingarm” setup.
Obvious, right? But there’s more to it than you might think. For example, why do some bikes only have one swingarm?
Why do some bikes have only one swingarm?
Original image by Zoweee at English Wikipedia, Public domain, via Wikimedia Commons
It’s not all about style – bikes with a single-sided swingarm setup have less unsprung weight compared to double-sided swingarms.
And the more you can reduce unsprung weight, the better.
Would you like to discover what ‘unsprung weight’ is? Listen to the 30-Minute Motorcycling Podcast episode about motorcycle suspension and suspension terminology:
It’s also easier and certainly quicker to remove a rear wheel from a motorcycle with a single-sided swingarm.
But why do some motorcycles still have double-sided swingarms?
Even though removing a wheel from a bike with a single-sided swingarm is technically easier, if your bike doesn’t have a center stand, it’s also harder since you’ll need to get a paddock stand.
Swingarm Length – And How It Affects Your Motorcycle
It’s easy for the untrained eye to dismiss the swingarm’s length as insignificant – but it is.
The further forward the swingarm is, the further forward the bike’s overall center of gravity is.
For this reason, drag racing motorcycles have extended swingarms – they prevent the bike from popping a wheelie at the start during quick accelerations.
