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Why Are Motorcycles So Loud?

I have often found myself in my old car with the windows down, cruising on the backroads when all of a sudden a thunderously loud motorcycle comes up the side of me and shoots by. 

There are no two ways about it, motorcycles are loud, louder than much bigger vehicles on the road sometimes. 

If you are a biker like me then most of the time you won’t mind and you can enjoy the loud exhaust notes that carry through the air. However, not everyone does and not everyone understands why motorcycles are so loud.

why are motorcycle loud
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Reasons why motorcycles can be so loud:

  • The muffler and exhaust pipe on a motorcycle are short so there is little time and space for sound to be absorbed unlike in a car. 
  • A motorcycle engine is exposed to the elements and there is no way for it to stop the noise unlike a car which usually has the engine encased in a compartment.
  • Manufacturers sometimes have no choice but to build a loud motorcycle engine as it can be a bi-product of performance features, layout and design. 
  • Some riders will switch out their exhaust system for an aftermarket one which can increase its noise levels, equally some riders opt to ride aggressively and make themselves heard when out on the road.
  • Some manufacturers have a reputation for producing a certain exhaust note and therefore it is part of their marketing to appeal to their audience. 

Let’s get into a bit more detail.

Why are Motorcycles so Loud?

To be clear, not all motorcycles are loud but they do have a reputation for being so. 

The problem is just like the loudest person in the room is the one who gets heard, it is the loud motorcycle on the street that gets noticed. The quiet commuter bikes with small-mid size engines go relatively unnoticed while the big roaring V-twins and screaming liter bikes get heard, seen and cursed at. 

Much like not all motorcyclists are ruthless outlaws, not all bikes are loud, but if they are it is often just down to the way they are designed more so than riders wanting to be a menace on the road. 

Exhaust System

The sound coming from an engine passes down through the exhaust system. This is true of many vehicles and doesn’t just apply to motorcycles. 

A stock exhaust system can contain a muffler, catalytic converter and baffles among other things which dampen the sound.

However, the problem with a motorcycle is that the whole exhaust system is pretty small when compared to that of a car and so there isn’t always room for the extra bits that would help make the bike quieter. 

Bikes are designed to be lightweight and compact, when you add to the fact that they are built to be aesthetically pleasing, the exhaust system needs to serve function over anything else including noise levels. 

The air rushing out of a 3ft-4ft long motorcycle exhaust has no time to slow down and neither is it encased within the machine for some of the noise to be absorbed. Whereas a car exhaust can be fitted with all the extras and run the length of the car along with some twists and turns which results in a slower air expulsion and makes it quieter. 

Mufflers

As with the exhaust pipe, motorcycle mufflers are very small compared to that of other vehicles so while they may dampen the exhaust noise somewhat it only has a limited capacity as to how much sound it can actually absorb. 

Engine Noise

Motorcycle engines come in a vast range of cubic capacities (what does CC mean?) and designs with some being naturally louder than others. 

What they all share in common is that unlike other vehicles their is no engine compartment encasing so motorcycles are limited in how much engine noise they can reduce. 

Lightweight single-cylinder and parallel twin engines are often quite quiet, surprisingly so, but big capacity V-twins and inline-four engines are more likely to be inherently loud motorcycles.

V-twins for example typically have two large pistons that create that well known “Pop, Pop, Pause” as the mini explosions go off within the cylinders. 

These kinds of engines run at very low RPM’s and so are loud bikes even when idle. 

Superbikes and their naked bike siblings with inline-four cylinder engines tend to have smaller pistons that work over a shorter distance but at high RPM’s, this results in insane horsepower output but equally a high and loud pitched exhaust note as the engine works overtime to produce the power. 

While cars with multiple cylinders have them sat in a compartment with plenty of other bits around them and it is all enclosed making for a quiet ride, a motorcycle is open for the world to hear. 

Aftermarket Exhausts and Manufacturer Marketing

A huge part of the motorcycle market is aimed at those looking to ride for leisure, motorcycling is fun and it is something people do with their downtime. 

That is partly why so much effort goes into the design of a motorcycle. Sure much of it is performance based, but styling is equally if not more important for many manufacturers. 

Part of the thought process therefore accounts for how the motorcycle sounds, manufacturers will deliberately produce motorcycles that sound good (at least to their audience’s ears). 

Some of us remember the zip zip brap of the classic two-strokes and that noise is synonymous with rebellion, fun and youth. Whereas the thundering rumble that comes out of a Harley Davidson V twin engine also evokes emotions for many riders too. 

So manufacturers produce bikes that fit in with the overall marketing package and sometimes that means they are sometimes extremely loud. 

You will have also likely heard the “Loud Pipes Save Lives” slogan that gets thrown around, many riders switch out their exhausts for aftermarket pipes to make their bikes sound better and usually that means louder. 

Some remove the stock mufflers to get straight pipes which increases the volume significantly. 

How Loud is Too Loud for a Motorcycle?

Anything over 85dB would be considered too loud for a motorcycle. The reason being that being exposed to noise of this level for a sustained period of time can lead to hearing damage. 

This is partly why government agencies have put in restrictions with regards to the amount of noise a motorcycle can produce. 

Motorcycle Noise Laws

Today there are noise pollution regulations in place in many countries that prohibit motorcycles from breaching a certain noise limit. 

In the US most motorcycles produced after 1986 are required by the EPA to be no louder than 80dB when stationary or 84dB when moving at 35mph. 

As a result manufacturers produce their motorcycles to meet these standards.

Aftermarket exhaust companies also need to meet these standards for the exhaust systems relevant to the date of manufacture. 

These standards do not apply to motorcycles prior to 1986, mopeds or off-road motorcycles. 

In the UK the legal noise limit is also 80dB with another 6dB extra allowed for mechanical noise. 

Therefore any motorcycle breaching these noise restrictions in the US or UK would be considered pretty loud. 

Whether the rider and other road users consider them to be too loud is completely subjective and down to the individual. 

Quite often sports and liter bike riders will fit aftermarket exhaust systems to their bikes which will break the decibel limit. The only reason manufacturers can produce these exhausts is to state them to be for “race-only” ; however, riders don’t always stick to this rule. 

Why Are New Motorcycles Quieter Than Older Motorcycles?

New motorcycles are quieter than older motorcycles as they have even more restrictions placed on them not just in regards to noise limits but in regards to the emissions they are allowed to produce. Reducing emissions usually results in a lower noise level.

Furthermore older motorcycles have mufflers that will have broken down with use over time and be far less effective than when they were new. 

New motorcycles are fitted with mufflers produced out of the latest materials and designed using the latest technology which means they are more effective at absorbing some of the noise. 

Also engine design has evolved over the years, and modern engines are more refined than older ones, with smoother parts so these too are quieter. 

Do Loud Motorcycles Really Save Lives?

Not really, it is a bit of a myth that loud pipes save lives, but some motorcycle riders swear by it. 

The fact is safe riding, constant visual checks, and making yourself as visible as possible through road positioning is going to save your life far more than having a loud sound will. 

One of the most common factors in motorcycle accidents is that unaware car drivers didn’t see the motorcycle. It is unlikely that your loud bike is going to prevent you from having an accident in this situation. 

Cars are enclosed spaces where drivers can have their air con on, windows up, kids talking in the backseat and music on. Outside noises are irrelevant until you are right on top of the vehicle itself. 

How many times are you in traffic with a police car or ambulance coming up behind and you see the car in front not move over because they haven’t heard the siren let alone checked their mirrors?

Focus on your defensive riding skills to keep yourself safe on the road, don’t depend on being seen or heard. 

Can Loud Motorcycles be Made Quieter?

It is possible to make your motorcycle quieter by installing quiet aftermarket silencer-type exhaust pipes or to install a new muffler. 

Fitting a new baffle into the muffler to decrease the sound can also be done, or the original can be wrapped to have the same effect. 

Be sure to check your model of motorcycle and exhaust system to make sure you make the correct modification if this is the route you want to go down. 

Are Electric Motorcycles Too Quiet?

The Harley Davidson Livewire is one of the best electric bikes on the market but is it too quiet?
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The Harley Livewire is one of the best electric bikes on the market but is it too quiet?

There is some noise from the motor and belt but when compared to a combustion engine they are practically silent motorcycles.

Some riders see this as an added bonus of going electric whilst I’ve spoken to other motorcycle enthusiasts who feel loud noises are part and parcel of riding.

Interestingly, I remember reading sometime ago that the NHTSA wanted electric motorcycles to have minimum noise limits. This was nothing to do with “loud pipes saves lives” and more to do with helping pedestrians, the visually impaired and children to hear e-motorcycles coming when crossing the road.

Akrapovic, the aftermarket exhaust systems manufacturer recently released the Akrapovolt for e-motorcycles. 

The Akrapovolt allowed you to choose between four distinct motorcycle engine sounds, the 2 stroke screamer, the big V-twin cruiser, the V-four Italian sports bike or the cross plane four cylinder Japanese sports bike.

It seemed a great idea but it looks like they jumped the gun in thinking buyers of these electric machines actually wanted to sound like a traditional motorcycle.

According to Sports Bike Shop it has been discontinued barely a year after being released. Maybe the next generation of motorcycle riders are happy to motor along in near silence.

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