Dirt Bike vs Motorcycle: 8 Differences That Matter
Written by Louis Pretorius
I am sure most of you know that a dirt bike is a motorcycle, but not all motorcycles are dirt bikes! When we talk of motorcycles here, we mean the street bike variety. Dirt bikes are a special breed of motorcycle. There are significant differences between these two machines. Our discussion of dirt bike vs motorcycle: 8 differences that matter, highlights the major differences between these two types of motorcycle. Those of you who are street bike riders but want to get into off-roading will find this article interesting as well as beginners to the world of motorcycles in general!The most important differences between these bikes are; whether they are street legal, the size of the bike, the weight, suspension construction, tires, riding position, performance in the dirt, and of course, the price! The price aspect includes not only purchase price, but also the cost of ongoing maintenance.Dirt bikes are, as their name implies, specifically designed with off-roading in mind. For this reason, they have evolved in both shape and technology to cater to the terrain they are intended for. Street motorcycles have similarly been designed for a different purpose and the design and technology have moved in a different direction.
The contrasting purposes for which these types of motorcycles have been developed have led to several significant differences between these two machines. A rider, who is used to a street bike and how it performs, may not be comfortable when first climbing aboard a dirt bike and vice versa!
Let’s get into the 8 differences that matter between a dirt bike and a street-legal motorcycle.
Street Legal Differences
Normal road bikes come with all the accouterments required to make them legal to ride on the city and suburban streets and highways. There are legal parameters that any motorcycle must comply with in order to qualify as street legal and prevent you from being pulled over by the police and facing a stiff fine, or worse!
The items required for a motorcycle include, but are not limited to:
- A headlight for the purpose of night riding.
- A tail light, also for night riding.
- Brake lights, for other road users behind you, to see when you hit the brakes.
- Front and rear left and right turning indicators to show motorists when you intend to make a turn.
- Roadworthy certificate to prove the vehicle meets the street legal requirements.
- Registration with municipal authorities to get a license plate to identify the motorcycle and the owner.
Street motorcycles come standard from the factory with all the necessary fitments to comply with this list in order to make them street legal.
Most true dirt bikes are not manufactured with any of these requirements. The purpose behind the thinking is that the dirt bike is made for off-road use, and has specific requirements for this function. Many of the features that make dirt bikes great for use in the dirt make them unsuitable for use on city and suburban roads.
This makes dirt bikes, in their pure form, not legal for use on the streets. This statement does, however, come with a caveat. Manufacturers have seen the need for a crossover variety of the dirt bike for riders who want or need a dual-purpose motorcycle. These bikes are engineered from the same stable as the off-road variety, but the legal requirements for street riding are all included on the bike.
A good example of a crossover off-road bike that is dual purpose is the BMW GS series of bikes, which are street legal and yet have performed very successfully off-road. They have been used to great effect in many rally events, such as the Paris-Dakar event, which is notoriously hard on both rider and machine!
If you have a non-street-legal dirt bike, you will find that these bikes have no places to fit the electronics and lights required to make them legal. If you want to make your dirt bike street legal, you can buy kits to fit your bike that will serve this purpose.Most dirt bike riders, however, don’t bother with making their bikes street-legal and transport their dirt bike to the track or off-road trail on a trailer of the back of a pickup truck.
When it comes to size comparison between a dirt bike and a street motorcycle, there are some significant differences.
Dirt bikes need a higher ground clearance due to the nature of the terrain they are designed for. They need to be able to go over rocks, roots, stumps, and uneven ground without damaging the sump or underparts of the motor and chassis.This additional height requirement affects the seat height of the dirt bike. You will find that most dirt bikes are tall, and you will feel like you need longer legs when trying to climb aboard! As a result, when purchasing a dirt bike, the seat height measurement is a significant metric to take note of. Don’t buy a bike where you cannot reach the ground when sitting on the seat!
Road bikes or street-legal motorcycles are usually designed for speed on smooth roads that are free from major obstacles. For this reason, street motorcycles are usually low slung and have significantly less ground clearance than dirt bikes!
The implication of this is that in most cases, the seat height on road bikes is less of an issue for the rider is the case with dirt bikes. While the seat height on road bikes does vary between makes and models, it is not normally a vast difference that requires consideration, unless the rider is shorter than average.Dirt bikes are also generally shorter in length than road motorcycles.Dirt bikes need the shorter chassis to make them more nimble around tight corners of a track or around obstacles on a trail ride. Street motorcycles are generally longer, designed for taking more sweeping corners at speed.
The only possible exception to the length difference is with the street café racer style motorcycles. These bikes are designed with a shorter chassis, very similar to the length of dirt bikes!
The length difference is a factor that needs to be considered mostly for buying a trailer to transport your bike. Most dirt bikes will also fit on the back of a pickup truck, but this may be more of a challenge with a street motorcycle!
The Weight FactorWhen the factor of weight is considered between these two types of motorcycles, street motorcycles are definitely the heavyweights, and by a significant margin!
Let me clarify this by saying that while you do get lightweight road bikes in the lower engine capacities, I consider these bikes to be more scooters than motorcycles. Generally, I consider a road motorcycle to be anything from a 500cc upwards to fall into this category.
But there is always an exception to the rule. In years gone by, Yamaha produced a very light and nifty little 2-stroke road bike, the Yamaha RD350LC. But these smaller engine bikes cannot match the performance of the modern superbike!
Road motorcycles generally have 4-stroke engines, which are mostly heavier and bulkier than the 2-stroke motors in dirt bikes.
While 4-stroke dirt bikes are available and popular among some riders, the more common dirt bikes are the 2-stroke variety. Dirt bikes generally have smaller engine capacity than many of the popular road motorcycles. This is especially true of the dirt bikes that are popular among beginner dirt bike riders.Dirt bikes have lightweight frames that are also lighter than most road motorcycles. For this reason, and their lack of necessary roadworthy items contributes to their overall lighter weight class than their road riding cousins!
If we compare the weights of comparative engine capacities for both types of bikes, you will get the idea. A 250cc dirt bike will weigh in the region of 215 to 220 pounds. A 250cc road bike typically comes in at 350 pounds. This is a significant weight difference of over 100 pounds!
As the engine capacity goes up, the corresponding weight of the motorcycle goes up significantly. A street motorcycle with a 1000cc motor can weigh anywhere up to 500 pounds! If your road bike is a cruising motorcycle like the much-acclaimed Honda Goldwing or a Harley Davidson FLHR Road King, then the weights can top out at more like 780 to 812 pounds! These are some serious heavyweights!These kinds of weights are pretty much unheard of in the realm of dirt bikes! Dirt bikes need to be agile and lightweight in order to perform practically and competitively in the off-road sector!
Once again, when comparing the technology behind these two motorcycle types, the major differences are due to the difference in the purpose of the two machines. The suspension system is a prime example of this difference due to function.
The terrain on which dirt bikes are used can, in most cases, be described as extreme! The ground is very uneven; there are obstacles such as large stones and rocks, branches and tree roots, sand, and mud! The suspension required to handle these extreme environments needs to be able to cope with the challenges that the terrain throws at it.Shock absorption for a dirt bike rider is of paramount importance. The bouncing around over rough ground would otherwise make the dirt bike uncontrollable! Poor shock absorption will not only make the ride uncomfortable and cause the rider to suffer from fatigue faster but could rip the handlebars out of the rider’s hands. This can make for a dangerous situation, particularly over the rough ground!
These extreme conditions that dirt bikes are expected to cope with have resulted in suspension technology developments specific to the dirt bike. Many dirt bikes have an adjustable suspension to make it a quick and easy task to adjust the suspension for different environmental conditions.
The difference in the suspension on a dirt bike means that there will be an enormous amount of travel of the suspension as it compensates for the rough ground. This travel can be as much as 12 inches or more. The larger suspension is a contributing factor to the difference in height between a street bike and a dirt bike.
This additional suspension on a dirt bike is another reason it can be an uncomfortable ride on the normal city or suburban roads.
When street bike riders climb aboard a dirt bike, they will often find the suspension to be significantly harder than what they are used to. This changes the overall feel of the ride and takes some getting used to.Street motorcycle suspension systems are made to handle minor imperfections in the road surface and give a smoother ride. This makes their suspension seem comparatively soft compared to that of a dirt bike. The road bike suspension is designed to keep the tires in contact with the road surface as much as possible to maintain traction and keep the tires gripping the surface, particularly in corners.
Tire manufacturers of both dirt bike tire and street bike tires invest millions in improving tire technology for each environment. This has resulted in tires that are excellent for street conditions and tires that perform exceptionally in the dirt! There are very few tires that work well in both environments!
Any dirt bike rider who has ventured out onto normal roads with knobbly tires on their dirt bike will testify to the fact of their lack of road holding on modern streets!Dirt bike tires are designed to provide grip in sandy, muddy or rough terrain. The wide gaps in the tread of the tire, giving the knobbly effect is a design strategy to help the tire shed mud and continue to provide grip. These same tires on a normal road surface reduce the amount of rubber that is in contact with the road surface. This makes them almost feel slick and slippery on a city road surface.
A road motorcycle tire is very different in comparison. They are designed to maximize surface contact with the road. The treads are designed to channel water away from the contact point between the tire and the road surface to prevent aquaplaning across the wet road.
The compounds that tires are made from differ between the two types of motorcycles. Dirt bike tires are made from different rubber compounds depending on the purpose or terrain that the tire is manufactured to cope with.
There is a wider range of tires manufactured for dirt bikes than for road bikes. This is largely due to the many different environments that the dirt bike is used compared to a road bike. This also means that as a dirt bike rider, you will probably have multiple sets of tires for your dirt bike. You will fit tires appropriate to the terrain before you head out for your off-road riding.
It is unlikely that you will have multiple sets of tires for your road bike and change them out before you ride. There are just not that many variations on the road surface that warrant different specialist tires to be fitted to your bike!
Most dirt bike tires are narrow in comparison to tires made for the streets, except for tires designed for sandy conditions or mudding! Another reason for this is weight reduction. Rubber is heavy, and dirt bike riders want their bikes to be a light as possible!
Riding PositionThe riding position is an aspect that even differs within the street bike style of motorcycles. Superbikes that are modeled on motorcycles designed for speed and performance have a particular riding position. This position is, typically, with your rear end on the seat and a leaning forward over the fuel tank posture.
This riding position is all about speed. It reduces the drag from wind resistance that your body would cause in an upright riding position. Some people find this riding position uncomfortable for long periods. This is because the position causes much of your upper body weight to be supported by hands, wrists, and shoulders. Overextended periods, this riding position can result in fatigue in the arms and shoulders.
Road motorcycles that are built as cruisers take a totally different stance when it comes to riding position! The riding position on these bikes is intended for an extended time in the saddle! The riding position is usually upright, very similar to sitting in an armchair! With some of these cruiser type motorcycles, the riding position has the rider’s legs extended forward so that they are in a straight position as opposed to being bent at the knee! This helps prevent cramping of the leg muscles during long rides!Dirt bikes in comparison to these road bikes are very different again when it comes to riding position! Dirt bike seats are not made to be a comfortable cushion for your rear end. This is due to a number of reasons unique to off-road motorcycle riding.
The first reason a dirt bike seat is not built for comfort is for weight reduction. Dirt bikes have a minimalist approach when it comes to creature comforts! The less weight helps to keep the bike light and nimble.
The second reason is that the riding position of off-road bikes is often in a standing position. The rider stands up on the footpegs and leans slightly forward towards the handlebars. This is known as the attack position and is particularly used on corrugated sections of ground or jumps. This riding position allows the legs and knees to act as shock absorbers, reducing some of the bouncing around caused by the rough nature of the terrain.
There are many riding positions that you need to master when dirt bike riding. Most of these different positions relate to compensating for the different types of terrain and for how the bike reacts to these differences. These positions vary from positions of the foot on the footpegs, to how the bike is gripped with the knees, to the positioning of your upper body to adjust the center of gravity.Riding a dirt bike requites so many changing positions that once you get off your bike, you feel like you have had a complete body workout!
Performance In The Dirt
Any street motorcycle rider who has ever had the misfortune to encounter a gravel road on their street bike will attest to the fact that even this small deviation in surface type changes the way the bike reacts. The front end and the steering immediately feel sloppy and become very unstable. The rear of the bike feels like it constantly wants to break away as soon as it deviates from straight-line travel.
This can make it a rather disconcerting experience the first time you encounter a dirt road on a road bike! The only way to negotiate this type of terrain on a street motorcycle is slowly!
While this type of environment is where street bikes are totally out of their depth, it is what dirt bikes were bred for! The development that has gone into perfecting the technology of dirt bike design really shows its metal in this environment. The speed and power with which riders can navigate through rough terrain is a testament to this!Take a dirt bike out of its natural environment, and the advancements in technology that gave it the edge now work as a disadvantage! The dirt bike is an uncomfortable, unpredictable ride on normal roads. The bike will require modifications to make it suitable, and indeed legal to operate in this unfamiliar environment! Certain tire manufacturers have brought out road tires for dirt bikes to make this transition legal and safer for dirt bike riders.
Dirt bikes are generally much simpler machines than street bikes. Street bikes are loaded with electronics for the engine, fuel, and brake management, while this is seldom the case with dirt bikes.
Street bike engines are also usually much larger and more finely tuned that dirt bike motors. You will find that all these factors will influence the purchase price when you compare the cost of these two motorcycle types.
The average price for a really good dirt bike, brand new is in the region of $8000 to $9000, so it is safe to say you can get a really good bike for under $10 000 purchase price. These prices are for the mid-range bikes. More sort after and upper market bikes such as some in the KTM brand can cost you upwards of $1200. You can, however, get a good off-road bike for under the $5000 mark.
When it comes to street motorcycles, you can get yourself a speed machine for around the $5000 price, but generally, the price for the more upmarket machines are well over $10 000! For example, the 2020 Ducati Panigale V2 which is a 955cc beast will cost you a cool $16 500!
The amount of money you put into your motorcycle does not stop at the purchase price! Dirt bikes are usually simpler, easier, and cheaper to maintain, but those with 2-stroke motors often require more regular maintenance. You also need to consider the variety of tires you will need for the different environments you will ride, and the costs of transporting your bike to riding locations.
Road bikes, being much more complicated machines, often require specialist mechanics, tools, and equipment in order to maintain these machines correctly. This comes with a relatively higher price tag than for dirt bikes.
We hope you have enjoyed discovering the differences between dirt bikes and street motorcycles! They both have their advantages in the right environments and disadvantages in the wrong environments. What matters is that you get out there and enjoy your bike, whichever version you choose to ride!