Electric bikes, also known as e-bikes, have become increasingly popular as an efficient and eco-friendly mode of transport.

E-bikes are a low cost transport option – about 5p per mile excluding depreciation. The carbon emissions of an e-bike are also about 1/100th of those of a car – typically 2g per mile compared with 200g.

In the UK E-bikes are limited to 15.4mph – and typically have a range of 30 to 60 miles depending on the battery size and terrain.

When choosing an e-bike, one of the essential decisions to make is the type of motor placement: front hub, rear hub, or centre drive.

Each system offers its distinct set of advantages and drawbacks. No matter the choice, all three systems provide the primary benefit of an e-bike: the added assistance to make cycling more accessible and enjoyable for a broader range of people. Whether commuting, exercising, or leisure riding, there’s an e-bike motor placement perfect for every cyclist.

1. Front Hub Motor:

Pros:

• Simple Design: The front hub motor is straightforward, typically requiring less maintenance and fewer components than other motor systems. This simplicity often makes them less expensive.
• Even Weight Distribution: Placing the motor on the front wheel can balance the bike, especially if the battery is towards the rear.

Cons:

• Traction Issues: In slippery conditions or during heavy acceleration, the front wheel might lose traction more easily than the rear.
• Handling: Having a motor in the front can alter the bike’s handling, especially during sharp turns. It might feel different than what traditional cyclists are accustomed to.

2. Rear Hub Motor:

Pros:

• Natural Feel: With the motor on the rear wheel, it gives a more conventional biking sensation as the push comes from behind.
• Better Traction: Rear wheels typically have better grip, especially during acceleration or uphill rides.
• Simple Retrofit: For those converting a traditional bike into an e-bike, rear hub kits are often more straightforward to install than other systems.

Cons:

• Weight Distribution: With both the motor and often the battery at the rear, the bike can feel back-heavy. This imbalance might make it harder to lift or maneuver when not riding.
• Maintenance: Changing a rear tire or fixing a flat can be more complicated with a rear hub motor than with a front hub or centre drive system.

3. Centre Drive (Mid-Drive) Motor:

Pros:

• Efficiency: Centre drive motors are known for their efficiency, especially in hilly terrains. They leverage the bike’s gears, adjusting to the rider’s speed and the slope of the terrain.
• Balance: By placing the motor in the middle of the bike, it offers an even weight distribution, resulting in stable and predictable handling.
• Performance: Mid-drives generally provide more torque, making them suitable for steep inclines and off-road conditions.

Cons:

• Cost: Centre drive systems are often more expensive than hub motors due to their complexity and performance advantages.
• Maintenance: These systems can put more strain on the bike’s drivetrain, possibly leading to more frequent maintenance or replacement of components like chains and cassettes.

Your choice between front hub, rear hub, or centre drive motors should be based on your specific needs, budget, and preferences. If you’re seeking a budget-friendly option and mainly ride on flat terrains, a front hub might suffice. For those wanting a more traditional bike feel and occasionally deal with hills or slippery conditions, a rear hub could be ideal. However, if you regularly tackle steep terrains, require maximum efficiency, or just want the best performance regardless of price, then a centre drive system would be the top pick.

E-Bike Cost Calculations

1. Electricity Cost for Charging: The cost of electricity in the UK varies, but as of my last training data up to 2022, it’s around £0.15 to £0.20 per kWh.
2. Battery Capacity and Efficiency: A common e-bike battery capacity is about 500Wh (0.5 kWh). On a full charge, many e-bikes can travel between 20 to 70 miles, depending on the level of assistance used, terrain, rider’s weight, and other factors. For this calculation, let’s take an average of 45 miles on a full charge.

Electricity cost for a full charge = 0.5 kWh * £0.17 (taking an average rate) = £0.085

Cost per mile = £0.085 / 45 miles = £0.00189 or approximately 0.19p per mile.

Maintenance Costs: While e-bikes have minimal ongoing costs, it’s essential to consider occasional maintenance like brake adjustments, tire replacements, and chain lubrication. Estimating these costs can be a bit trickier because they depend on usage, care, and specific components. Still, a ballpark figure might be about £50 per year if you ride regularly.

If you ride an average of 1,000 miles per year (just 20 per week), the maintenance cost would add:

Maintenance cost per mile = £50 / 1,000 miles = £0.05 per mile.

Total Cost per Mile (excluding depreciation): Combining electricity and maintenance costs: = 0.19p + 5p = approximately 5.19p per mile.

Carbon Cost Calculations

It’s tricky to calculate the exact carbon cost per mile of an e-bike compared to a car – so we’ll make a few assumptions based on typical data.

1. E-bike Carbon Emission:

Electricity generation in the UK is increasingly green, but it’s not entirely carbon-free. As of my last update:

• UK Grid Carbon Intensity: Approximately 200g CO₂/kWh.

Using our earlier 0.5 kWh battery that lasts for 45 miles:

Carbon cost of charging = 0.5 kWh * 200g CO₂/kWh = 100g CO₂ for 45 miles

E-bike CO₂ emission per mile = 100g / 45 = 2.22g CO₂/mile.

2. Car Carbon Emission:

The CO₂ emission of cars varies significantly based on the model, fuel type, and efficiency. A reasonable estimate for a typical petrol car:

• Petrol Car Carbon Emission: Approximately 120g CO₂/km or about 193g CO₂/mile.

Comparison:

• E-bike: 2.22g CO₂/mile
• Petrol Car: 193g CO₂/mile

Thus, on average, a car emits roughly 87 times more CO₂ per mile compared to an e-bike.