Choosing between a 70cc and 125cc dirt bike is mainly a question of rider fit, operating skill and readiness for a manual clutch. A 70cc semi automatic dirt bike is generally easier for a smaller or less experienced rider to operate, while a 125cc manual dirt bike is better suited to a physically larger rider who is ready to learn clutch control and gear changes.
Engine size should not be the only deciding factor. Seat height, wheel size, control reach, balance, strength, maturity and access to suitable off road terrain are equally important.
This guide compares the Venom MX70 70cc Semi Automatic Dirt Bike with the Venom Thunder 125cc Manual Dirt Bike to help Canadian buyers choose the better fit.
Quick recommendation
Choose the MX70 70cc for a smaller rider who fits its 25 inch seat height and would benefit from a semi automatic transmission without a hand operated clutch.
Choose the Thunder 125cc for a taller rider who fits its 33 inch seat height and is ready to learn a four speed manual transmission and clutch control.
70cc vs 125cc Dirt Bike Comparison
| Feature | Venom MX70 70cc | Venom Thunder 125cc |
|---|---|---|
| Engine size | 70cc | 125cc |
| Transmission | Semi automatic | Four speed manual |
| Clutch operation | Automatic clutch with no hand clutch lever | Hand operated clutch |
| Seat height | 25 inches | 33 inches |
| Wheel sizes | 10 inch front and rear wheels | 17 inch front and 14 inch rear wheels |
| Starting system | Kick start | Kick start |
| Highlighted control feature | Keyed ignition | Adjustable speed governor |
| Best fit | Smaller riders learning balance, braking and shifting | Taller riders ready to learn manual clutch control |
| Canadian parts collection | MX70 parts | Thunder parts |
Specifications and available configurations may change. Review the current product pages before ordering.
What Is the Main Difference Between a 70cc and 125cc Dirt Bike?
The largest practical difference is not only engine displacement. The two motorcycles have very different physical sizes and transmission systems.
The MX70 is a compact dirt bike with a 25 inch seat height, 10 inch wheels and a semi automatic transmission. The rider changes gears, but the automatic clutch removes the need to coordinate a hand operated clutch lever.
The Thunder is a taller motorcycle with a 33 inch seat height, larger wheels and a four speed manual transmission. The rider must coordinate the clutch, throttle and gear selector while also managing braking, steering and balance.
For a first time rider, the transmission difference can be as important as the engine size.
Which Dirt Bike Is Easier for a Beginner?
The MX70 is generally simpler to learn because it does not require manual clutch operation. The rider can focus on:
- Starting and stopping smoothly.
- Maintaining balance.
- Steering through turns.
- Using the front and rear brakes.
- Learning when to change gears.
- Maintaining a controlled riding position.
The Thunder adds manual clutch engagement to the process. A rider starting on the Thunder must learn how to release the clutch smoothly while applying the correct amount of throttle.
This does not mean every beginner should automatically choose the smaller bike. A taller rider may be physically cramped on the MX70 and may fit the Thunder more naturally.
Rider Fit: The Most Important Buying Factor
A dirt bike should be selected by physical fit and control ability rather than age alone.
Seat Height
The MX70 has a listed seat height of 25 inches. The Thunder has a listed seat height of 33 inches, creating a substantial difference in overall rider position.
The rider should be able to stop and balance the motorcycle without excessive stretching or immediately losing control. Both feet do not necessarily need to rest completely flat, but the rider must be able to support the motorcycle confidently.
Control Reach
While seated in a normal riding position, the rider should be able to:
- Turn the handlebars through their normal range.
- Operate the throttle without repositioning the hand.
- Reach the front brake lever comfortably.
- Reach the rear brake pedal and gear selector.
- Operate the clutch lever on the Thunder without excessive stretching.
- Keep both feet securely positioned on the footrests.
Strength and Balance
The rider should be able to hold the motorcycle upright, move it at walking speed and recover from a slight lean. A motorcycle that feels manageable on a level showroom floor can become more difficult to control on loose or uneven terrain.
Riding Position
The rider should not appear excessively cramped or stretched. Knees, elbows and shoulders should remain in a comfortable position that allows movement while standing or sitting.
70cc Semi Automatic vs 125cc Manual Transmission
How the MX70 Semi Automatic Transmission Works
The MX70 uses a semi automatic transmission with an automatic clutch. The rider selects gears using the foot control, but does not operate a hand clutch lever.
This allows the rider to learn gear selection without coordinating clutch engagement at the same time.
A semi automatic bike may suit a rider who:
- Has little or no previous motorcycle experience.
- Is still developing balance and braking skills.
- Is not physically comfortable operating a clutch lever.
- Would benefit from learning one skill at a time.
How the Thunder Manual Transmission Works
The Thunder uses a four speed manual transmission. The rider controls the clutch with the left hand and selects gears with the foot control.
This allows the rider to develop traditional motorcycle skills, but it requires more coordination.
A manual dirt bike may suit a rider who:
- Already understands basic throttle and brake control.
- Can reach and operate the clutch comfortably.
- Is patient enough to practise controlled starts.
- Is ready for the additional responsibility of clutch and gear control.
- Fits the larger motorcycle correctly.
Important: A simpler transmission reduces the number of controls the rider must coordinate. It does not replace training, protective equipment, responsible supervision or suitable terrain.
How Wheel Size Changes the Riding Experience
The MX70 uses 10 inch front and rear wheels. The Thunder uses a 17 inch front wheel and 14 inch rear wheel.
Smaller wheels contribute to the MX70’s compact height and make it easier for a smaller rider to fit the motorcycle. Larger wheels increase the Thunder’s overall size and can provide a different feel over uneven terrain.
Wheel size should be considered together with:
- Seat height.
- Suspension height.
- Rider inseam.
- Rider strength.
- The type of terrain.
- Previous riding experience.
When to Choose the Venom MX70 70cc
Consider the Venom MX70 70cc when the rider:
- Fits the 25 inch seat height and compact frame.
- Would be physically overwhelmed by a taller motorcycle.
- Is learning dirt bike balance and braking for the first time.
- Is not ready to operate a manual hand clutch.
- Would benefit from semi automatic shifting.
- Will practise on flat, controlled off road terrain.
The MX70 also includes keyed ignition, allowing the owner to control access to the motorcycle.
When to Choose the Venom Thunder 125cc
Consider the Venom Thunder 125cc when the rider:
- Fits the 33 inch seat height and larger frame.
- Can comfortably reach the clutch, brakes and gear selector.
- Is ready to learn a four speed manual transmission.
- Has previous experience with a smaller powered vehicle or motorcycle.
- Wants to develop traditional clutch and shifting skills.
- Needs a larger wheel and chassis configuration.
The Thunder also includes an adjustable speed governor. This allows available throttle to be restricted while the rider practises, but it does not make the motorcycle suitable for someone who cannot physically control it.
For more detailed guidance, read our 125cc dirt bike beginner and rider fit guide.
View the Venom Thunder 125cc →
Can a Beginner Start Directly on a 125cc Dirt Bike?
Some beginners can start on a 125cc dirt bike when they fit the motorcycle correctly and receive appropriate instruction. Others will learn more effectively on a smaller semi automatic bike first.
A beginner may be ready for the Thunder when they can:
- Balance and support the motorcycle.
- Reach every control comfortably.
- Understand separate front and rear braking.
- Practise clutch engagement without panicking or using excessive throttle.
- Follow operating boundaries and supervision.
- Ride in a controlled area away from public roads and vehicle traffic.
A rider who cannot reach the ground, clutch or brakes comfortably should not be placed on the larger bike merely because they may grow into it later.
Should a Rider Start on the 70cc and Upgrade Later?
Starting on the MX70 can be a practical progression when the rider fits the motorcycle today and is not ready for a manual clutch.
The rider can use the smaller bike to develop:
- Throttle control.
- Braking technique.
- Standing and seated body position.
- Gear selection.
- Turning and obstacle awareness.
- Basic maintenance habits.
An upgrade may make sense when the rider begins to feel physically cramped, has consistent control of the motorcycle and is ready to learn clutch operation.
Do not upgrade only because the rider has reached a particular birthday. Upgrade when physical fit and operating ability justify the change.
Protective Equipment and Responsible Operation
Both motorcycles are off road vehicles. Appropriate protective equipment should be used regardless of engine size.
- Properly fitted approved motorcycle or motocross helmet.
- Eye protection or goggles.
- Motorcycle gloves.
- Long sleeves and durable riding pants.
- Over the ankle riding boots.
- Knee, elbow and chest protection where appropriate.
New riders should begin on flat, open terrain away from traffic, steep slopes, water, loose obstacles and other riders.
These motorcycles should not be assumed to be street legal. Provincial, municipal and trail rules vary across Canada. Confirm where the motorcycle may legally be operated before riding.
Assembly and Pre Delivery Inspection
A dirt bike delivered by freight may require final assembly, inspection and testing before use.
Venom Motorsports Canada’s current terms require full assembly, pre delivery inspection and testing by a certified mechanic. This includes checking critical systems such as:
- Wheel and axle installation.
- Handlebars and steering.
- Throttle and brake operation.
- Clutch operation on the Thunder.
- Gear selection.
- Chain tension and alignment.
- Tire pressure.
- Engine oil and fuel connections.
- Suspension and accessible fasteners.
- Controlled operational testing.
Review the motorcycle and dirt bike PDI checklist and the current warranty and assembly terms before operation.
Maintenance Differences
Both bikes are gas powered mechanical vehicles and require regular maintenance. The main difference is that the Thunder’s manual clutch adds clutch adjustment and additional control inspection to the ownership routine.
| Maintenance area | MX70 70cc | Thunder 125cc |
|---|---|---|
| Engine oil | Regular checks and scheduled replacement | Regular checks and scheduled replacement |
| Air filter | Inspect more frequently in dusty conditions | Inspect more frequently in dusty conditions |
| Drive chain | Inspect tension, alignment and lubrication | Inspect tension, alignment and lubrication |
| Clutch | Automatic clutch system | Manual clutch lever and cable require inspection and adjustment |
| Brakes and tires | Inspect before every ride | Inspect before every ride |
| Fasteners | Recheck after initial use and periodically | Recheck after initial use and periodically |
Follow the owner’s manual and model specific instructions for exact service intervals.
Replacement Parts Support in Canada
Venom Motorsports Canada maintains dedicated parts collections for both motorcycles.
MX70 Replacement Parts
Browse the Venom MX70 replacement parts collection for model compatible mechanical, control and electrical components.
Thunder 125cc Replacement Parts
The Venom Thunder replacement parts collection includes model compatible items such as carburetors, clutch components, chains, brake assemblies, engine components and controls.
Shipping Gas Dirt Bikes Across Canada
Under the current Venom Motorsports Canada shipping policy, gas dirt bikes qualify for free shipping to the nearest Day & Ross terminal. The customer picks up the shipment using photo identification.
Optional scheduled residential delivery may be available for an additional charge. Additional delivery costs may apply when the address is located far from the nearest freight terminal.
Current estimated Canadian freight transit is generally between one and seven business days after shipment. Transit can be affected by destination, weather, carrier operations and order preparation.
Review the current Canadian dirt bike shipping policy before ordering.
Frequently Asked Questions
Is a 70cc or 125cc dirt bike better for a beginner?
The 70cc MX70 is generally simpler for a smaller beginner because it has a lower seat and semi automatic transmission. The 125cc Thunder may suit a taller beginner who fits the motorcycle and is ready to learn manual clutch control.
What is the seat height difference?
The MX70 has a listed seat height of 25 inches. The Thunder has a listed seat height of 33 inches. The eight inch difference makes rider fit a major part of the decision.
Does the MX70 have a clutch?
The MX70 uses an automatic clutch. The rider changes gears but does not operate a hand clutch lever.
Is the Thunder 125cc automatic?
No. The Thunder uses a four speed manual transmission with a hand operated clutch.
Should I buy a dirt bike that the rider will grow into?
Do not choose a motorcycle that the rider cannot safely control today. A bike that is too tall or difficult to operate can interfere with learning and control.
Can a beginner start on a manual dirt bike?
Yes, when the rider fits the motorcycle, can reach the clutch comfortably and receives appropriate instruction. A semi automatic bike may be a better starting point when clutch control would create too much additional difficulty.
Are these dirt bikes street legal?
They are sold as off road dirt bikes. Do not assume they can be registered or operated on public roads. Provincial and municipal rules vary.
Do the dirt bikes arrive fully assembled?
Most vehicles are shipped substantially assembled unless a full assembly service is selected. Final assembly, PDI and testing by a certified mechanic are required before operation.
Are replacement parts available in Canada?
Yes. Venom Motorsports Canada maintains dedicated replacement parts collections for both the MX70 and Thunder 125cc dirt bikes.
Shop 70cc and 125cc Dirt Bikes in Canada
The MX70 and Thunder are designed for different stages of rider development. The MX70 offers a lower seat, smaller wheels and a semi automatic transmission. The Thunder provides a taller chassis and manual clutch for riders who are physically and technically ready for the additional responsibility.
The correct choice is the motorcycle the rider can control confidently today, not simply the model with the larger engine.
Compare Venom Gas Dirt Bikes
Select the motorcycle that matches the rider’s current fit, experience and transmission readiness.
