Expert Review by: Stu Smith, Field Operations & Business Development Manager
This article was created in collaboration with Domex’s lead e-bike technician for accuracy and relevance.
Buying an electric bike is one of the more exciting purchases you can make. It’s also one where a bit of the wrong advice can cost you a lot of money. Read most retailer guides online and you’ll get a list of specs with no context, or a “best bikes” roundup that’s really just a shopping catalogue. This guide is different because it’s written from the workshop side by mechanics who service, diagnose and repair e-bikes across London and Surrey every day.
We’ll cover how to choose the right bike, what UK law actually says, the specs that matter versus the ones you can safely ignore, and (something almost nobody talks about) how to think about the long-term cost of owning an e-bike. Whether you’re a first-time buyer, a returning cyclist or someone considering an e-bike conversion instead of a brand-new purchase, there’s something useful here for you.
⚡ Key Takeaways: Buying Your E-Bike
- UK Legality: Only 250W motors that cut out at 15.5mph (25km/h) are road-legal without a license.
- Motor Choice: Mid-drive is best for hills and a natural feel; Hub-drive is great for flat city riding and budgets.
- Range Reality: Expect about 60% of the manufacturer’s stated range in real-world UK conditions.
- Maintenance: Budget for one pro service per year to keep your motor warranty and battery healthy.
Your Quick Guide: The Five Things That Actually Matter
Before you look at a single spec sheet, focus on:
- Your riding style and terrain
- The motor type: hub vs mid-drive
- Real-world battery range, not manufacturer claims
- Frame fit and comfort for your body
- If the bike meets UK EAPC legal standards.
Get these five right and the rest are minor details.
NB: Are Electric Bikes Legal in the UK?
This section is often buried at the end of buyer’s guides or skipped entirely. It shouldn’t be because buying the wrong e-bike can mean you can’t legally ride it on public roads at all.
In the UK, a road-legal electric bike must comply with the Electrically Assisted Pedal Cycle (EAPC) regulations. The rules are clear:
- The motor must have a maximum continuous rated output of 250 watts
- The motor must cut out when the bike reaches 25km/h (approximately 15.5mph) under motor power alone
- The bike must require you to pedal to activate the motor
- The rider must be at least 14 years old
A compliant EAPC bike requires no registration, no insurance (though it’s a good idea), no driving licence and no helmet (legally speaking: wear one). You ride it exactly like a bicycle.
Look for the EN15194 certification mark on any bike you’re considering. This is the European safety standard for e-bikes and confirms the motor, battery and electrical system have been independently tested. It’s the single best quick check you can do at the point of purchase.
Why are police targeting e-bikes? The crackdown is aimed at throttle-only e-bikes and bikes with motors above 250W, which are those often sold cheaply online. Legally, they’re classified as motor vehicles. Riding one on a public road without registration, insurance and a driving licence is an offence. The bike can be seized. At Domex Bikes, we only work on road-legal e-bikes and it’s worth checking this before you buy and not afterward.
To directly answer a question we see often: 500W and 750W electric bikes are not road-legal in the UK for general use. They’re fine on private land or if registered and insured as motor vehicles. But they cannot be ridden on public roads as bicycles.
How to Choose Your Motor: Hub Drive vs Mid-Drive
The motor is the heart of an e-bike and the choice between a hub motor and a mid-drive affects how the bike feels, climbs and holds up over time. Here’s what you actually need to know.
Hub motors
Hub motors are mounted inside the wheel hub (usually the rear wheel, occasionally the front). They push or pull the bike independent of the gears, which means they’re simple, generally cheaper to produce and perfectly adequate for flat or gently rolling terrain. If you’re commuting on flat city roads or cycling along canal paths, a rear-hub motor does the job without fuss.
The downside shows on hills. Hub motors work against a single fixed gear ratio, so climbing is less efficient and the battery drains faster when it’s working hard. Puncture repairs on a rear-hub e-bike are also more involved. The wiring has to be managed carefully, which is one reason we’d always recommend professional e-bike repair and servicing rather than a roadside bodge.
Mid-drive motors
Mid-drive motors sit at the bottom bracket at the axle where the pedals attach. They work through the bike’s existing gears, which means they can maintain an efficient motor speed whether you’re climbing a Surrey hill or cruising a flat cycle path. The weight distribution is also much better, sitting low and centred rather than in a wheel.
The trade-off is cost. Mid-drive bikes generally start higher in price and the motor puts more wear on the drivetrain (chain, cassette, chainring) than a hub setup. Budget for more frequent chain replacements if you ride hard.
Torque sensors vs speed sensors
This is worth understanding even if it doesn’t make the spec sheet headline. Most affordable e-bikes use “just” a cadence (speed) sensor. It detects that you’re pedalling and switches the motor on. The assist can feel sudden, like a push in the back.
A torque sensor measures how hard you’re actually pushing on the pedals and varies the motor output accordingly. The result is a much more natural, intuitive ride. The bike responds to your effort rather than just the fact that your feet are moving. Torque sensors are standard on premium systems like Bosch Smart System and Shimano STEPS. They’re one of the main reasons these systems feel so different from budget alternatives.
| Motor type | Best for | Typical systems |
| Rear hub | Flat commutes, leisure, budget | Generic, Bafang |
| Front hub | Simple retrofits, flat terrain | Generic, some folding e-bikes |
| Mid-drive | Hills, longer range, varied terrain | Bosch, Shimano STEPS, Yamaha, Fazua |
Battery Range: What the Specs Don’t Tell You
Every e-bike manufacturer quotes a range figure, and almost none of them are achievable in normal conditions. A bike advertised as offering 80 miles of range might give you 35–40 miles on a hilly London commute with a loaded bag. That’s not fraud. It’s physics. But it’s worth understanding before you open your wallet.
Understanding watt-hours (Wh)
Battery capacity is measured in watt-hours. The higher the number, the more energy it stores. A 400Wh battery is a reasonable entry point for regular commuting; 500–625Wh gives you more headroom. Anything above 625Wh is suited to longer touring or cargo use. These figures are one factor in range, but they’re not the whole story.
Real-world range is affected by:
- Rider weight: more weight means the motor works harder
- Terrain: hills are the biggest range killer
- Temperature: cold weather (anything below about 5°C) reduces lithium-ion performance noticeably
- Assist level: riding on maximum assist burns through battery much faster than Eco mode
- Speed: wind resistance increases exponentially (a 20mph headwind will drain a battery quickly)
A practical rule: Take the manufacturer’s claimed range, assume you’ll use a mix of assist levels and work backwards from 60% of the claimed figure as a conservative real-world estimate for hilly or loaded riding.
Also check whether the battery is removable. Many integrated batteries require you to charge the whole bike from a socket near where you park it. If you live in a flat or park on the street, that’s a serious logistical problem. Removable batteries (common on Bosch and Shimano-equipped bikes) can be taken upstairs and charged wherever is convenient.
For advice on maximising battery lifespan through the seasons, including winter storage tips, read our guide on how to make your e-bike battery last longer.
Choosing the Right Frame and Fit
You can have an excellent motor and a large, removable battery, and still end up with a bike you dread riding because it doesn’t fit properly. This is probably the most overlooked section of most buyer’s guides, and it matters particularly for anyone over 50, shorter riders or those with any mobility limitations.
Step-through vs diamond frame
A step-through frame has a very low or absent top tube, which means you can mount the bike without swinging your leg over the saddle. This isn’t just about comfort. For many riders, it’s a safety issue. Getting on and off a high-top-tube bike with a heavy e-bike (many weigh 20–28kg) is harder than it sounds, especially in traffic or on a slope.
A traditional diamond frame is stiffer, handles slightly better at speed and gives a sportier riding position. It’s the right choice if you’re prioritising performance over accessibility.
Getting the size right
E-bike sizing follows conventional bike sizing: the frame size is based on your height and inside leg measurement. Most brands publish sizing charts. Use them. An incorrectly sized e-bike is not just uncomfortable. It can cause real musculoskeletal problems over time, particularly in the lower back, knees and wrists.
Pay attention to:
- Saddle height: should allow a slight bend in the knee at the bottom of the pedal stroke
- Handlebar reach: too far means a hunched back, too close and you’re cramped
- Handlebar height: more upright is generally more comfortable for leisure and commuting / lower for performance riding
If possible, test-ride before you buy. If you’re purchasing online, check the return and exchange policy carefully.
Types of Electric Bike: Which One Suits Your Riding?
The “right” e-bike depends on what you’re actually going to do with it. Here’s a brief breakdown of the main categories and who each suits.
City/hybrid e-bikes
The most popular category for commuters and leisure riders. Upright riding position, typically hub or mid-drive motor, mudguards and rack mounts as standard. Good all-rounders for mixed terrain. Usually the most practical choice for anyone riding to work or doing regular errands.
Electric mountain bikes (e-MTBs)
Built for off-road riding: suspension forks, wide tyres, powerful mid-drive motor. They also happen to be excellent for hilly road commutes. The extra torque and gearing makes Surrey’s hills much more manageable. However, they’re usually heavier and more expensive.
Cargo and family e-bikes
Designed to carry loads such as children, shopping and delivery goods, they have long-tail designs (extended rear rack) or a front-loading “bakfiets” style. Mid-drive motors are almost always used here, as the extra load demands torque over raw speed. These are increasingly common for family use in London as a car alternative.
Folding e-bikes
Compact, foldable and well-suited to mixed-mode commuting (train + bike). Smaller wheels mean they’re less comfortable over longer distances but are unbeatable for convenience. Brompton Electric is the gold standard in the UK, though various alternatives exist at lower price points.
Road and gravel e-bikes
Drop-bar e-bikes are for faster road riding or mixed surfaces. They often feature very discreet motor integration and smaller batteries to keep the weight down. They’re better suited to experienced cyclists who want assistance without a heavy leisure-bike feel.
What Does an Electric Bike Actually Cost to Own?
The purchase price is only part of the picture. A few things worth factoring into your budget:
Purchase Price Tiers
Budget e-bikes (under £1,000) typically use hub motors with speed sensors and generic components. They work, but durability and component quality are often where corners are cut. The £1,500–£2,500 range is where quality genuinely improves. You start seeing Shimano and Bosch systems, hydraulic disc brakes and proper frame geometry. Above £3,000, you’re into premium mid-drive territory with the most sophisticated motor systems and longer-lasting components.
Cycle to Work Scheme
UK EAPC-compliant e-bikes qualify for the Cycle to Work Scheme. This is a salary sacrifice that typically saves you 25–40% through tax-free payments. While most people use this for the initial purchase, many modern schemes (like the Green Commute Initiative) also allow you to include professional maintenance and servicing in your voucher.
Annual servicing
Budget for at least one service per year. E-bikes need everything a standard bike needs (brakes, cables, drivetrain, tyres) plus e-bike-specific checks such as motor, battery contacts, display, wiring and increasingly, firmware updates. A yearly regular tune-up is far cheaper than fixing the accumulated damage of a neglected drivetrain.
Battery replacement
Lithium-ion batteries degrade over time and so do their charge cycles. A replacement battery from a major brand (Bosch, Shimano) typically costs £350–£700 or more. This is worth factoring into the long-term cost, especially if you’re considering a second-hand bike.
Buying second-hand: the risks
Second-hand e-bikes can be good value, but battery health is the critical unknown. A battery that’s done 1,000 cycles might only hold 80% of its original capacity and you often can’t tell from a visual inspection. If you’re buying used, it’s recommended that you get a Bosch or Shimano diagnostic check before you complete the purchase.
Red Flags: What to Avoid When Buying an Electric Bike
From what we see coming through for repairs, there are some consistent patterns in purchases people regret.
- No EN15194 certification. If a bike doesn’t carry this mark, you have no independent verification that the motor, battery and electrical system are safe. Walk away.
- Motor wattage above 250W that’s marketed as ‘road legal’. It isn’t. Some sellers describe the peak wattage (which can be much higher) rather than the continuous rated output. The number that matters legally is the continuous rated output.
- Range claims over 100 miles on a standard battery. This is almost always achieved under ideal (and unrealistic) conditions. Real-world range will be substantially lower.
- No UK-based customer support or spare parts. Pop-up brands that import directly from overseas often have no UK service network. When something goes wrong (and eventually something will) you may have no route to parts or technical support.
- No return or exchange policy. E-bikes are an investment. A reputable seller will offer a reasonable return window or test-ride guarantee.
- Throttle-only operation. A bike that moves without pedalling is not road-legal under EAPC rules. It’s a motor vehicle. Some are sold with the throttle function enabled. Disable it or avoid the bike entirely.
Should You Buy New or Used or Convert Your Existing Bike?
Not everyone realises that converting an existing bike to electric is a viable option. If you have a quality bike you already love (and it’s in good mechanical condition) an e-bike conversion can be a cost-effective alternative to buying new.
Conversion kits come in two main types: hub motor kits (fitted to the front or rear wheel) and mid-drive kits (fitted at the bottom bracket). Hub kits are simpler and cheaper to install. Mid-drive kits are more capable on hills but require a compatible frame and some more involved fitting work.
The key consideration for UK riders: conversions must still comply with EAPC regulations. The motor must be 250W maximum continuous output and must cut out at 25km/h. A poorly configured conversion kit can push you into illegal motor vehicle territory without any obvious visual clue, which is why professional fitting and post-fit calibration matters.
At Domex Bikes, our conversion service includes UK-legal configuration as standard: motor programmed to 250W / 25km/h with full error checks and a post-fit test ride. We’ll also give you a clear, honest assessment of whether your existing bike is a good candidate for conversion before any work begins.
How We Approach E-Bike Servicing at Domex Bikes
We’re not a retailer, so we don’t have a stake in selling you a specific brand. What we do have is a clear view from the workbench of what holds up and what doesn’t. As the UK’s first truly mobile bike service centre, we’re a Bosch Approved Service Centre and Shimano Service Partner, which means we have official access to diagnostic software, firmware, service bulletins and replacement parts for the two most widely used motor systems in the UK.
Our Cytech-trained mobile mechanics cover South London, SW London, and Surrey. We visit customers at home, at work or wherever a breakdown happens. What does a good e-bike service actually involve? Here’s what we check:
- Motor diagnostics: error codes, torque sensor calibration, seal integrity
- Battery contact condition and capacity check (where system supports it)
- Firmware updates via official Bosch Smart System or Shimano STEPS diagnostic suites and not third-party workarounds that can void warranties
- Drivetrain wear assessment (chain, cassette, chainrings): e-bikes wear these faster than standard bikes
- Brake check: hydraulic disc brakes are standard on most quality e-bikes and need periodic bleeding and pad replacement
- Wiring integrity and connector check, particularly on bikes that have been ridden in wet weather
- Tyre pressure and condition: e-bike tyres carry more load and wear differently
Our callout and assessment fee is £44.77 regardless of how many e-bikes are assessed at the same visit. From there, you only pay for what you approve. We offer a 28-day warranty against faulty workmanship on all repairs.
Conclusion
Buying an e-bike well means buying one you’ll still be happy with in two or three years. Not the one with the longest spec sheet or the lowest price tag. Get the legal compliance right, match the motor to your terrain, choose a frame that fits and budget for the ongoing care it needs. Do those things and you’ll have a bike that genuinely changes how you get around.
Our mobile mechanics are here whenever you need support: pre-purchase diagnostic checks, post-purchase servicing, software updates or anything in between. Give us a call on 0330 400 4000 or book a visit online.
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Frequently Asked Questions
How many watts should a good electric bike have in the UK?
For a road-legal e-bike, the motor must not exceed 250W continuous rated power. A quality 250W mid-drive from Bosch or Shimano will handle hills and loaded commutes comfortably. Don’t be tempted by higher wattage motors marketed as more powerful, because they’re not street-legal for everyday riding.
Is a 500W or 750W electric bike legal in the UK?
No. UK EAPC regulations cap road-legal e-bikes at 250W continuous rated output. Bikes with 500W or 750W motors can only be used on private land, or if fully registered and insured as motor vehicles, which defeats the point for most buyers.
What is the average lifespan of an electric bike battery?
Most lithium-ion e-bike batteries last 500–1,000 full charge cycles, typically three to five years of regular use. Proper care such as avoiding full discharge, storing correctly in winter and not leaving the battery fully charged for long periods can extend this considerably. Read our full guide on e-bike battery lifespan.
What are the biggest red flags when buying an electric bike?
No EN15194 certification, motor wattage above 250W described as ‘road legal’, unrealistically high range claims, no UK customer support or spare parts availability and throttle-only operation without pedalling. Any one of these is reason enough to look elsewhere.
What is the difference between a hub motor and a mid-drive motor?
A hub motor sits in the wheel and works independently of the gears. A mid-drive motor connects at the pedals and works through the gears, making it more efficient on hills and over varied terrain. For flat commuting, a hub motor is fine. For hills or heavier loads, mid-drive is worth the extra cost.
Can I use the Cycle to Work Scheme to buy an electric bike?
Yes. e-Bikes that meet UK EAPC standards qualify for the Cycle to Work Scheme, saving most employees 25–40% on the purchase price through salary sacrifice. Check whether your employer participates.
Why are police targeting e-bikes?
The enforcement is focused on throttle-only models and bikes with motors above 250W, both of which are legally classified as motor vehicles in the UK. Riding them on public roads without registration, insurance and a licence is a criminal offence. The bike can be seized on the spot.
What questions should I ask when buying an electric bike?
Does it have EN15194 certification? What is the continuous rated motor wattage? What is the real-world range on typical terrain? Is the battery removable? What warranty is included and is UK customer support available? Are replacement parts stocked in the UK?
How much does it cost to service an electric bike?
It depends on what’s needed. Budget for at least one professional service per year. At Domex Bikes, our callout and assessment fee is £44.77 and from there you only pay for approved work. Contact us for a quote tailored to your bike and needs.
Should I buy new or used or convert my existing bike?
New bikes carry full warranty and known battery health. Used e-bikes risk unknown battery degradation. A replacement battery can cost £350–£700+. If you already own a quality bike in good condition, an e-bike conversion is often the most cost-effective route to going electric.
About Domex Bikes:
The UK’s first truly mobile bike service centre. We’re a Bosch Approved Service Centre and Shimano Service Partner, covering South London, SW London, and Surrey. Our Cytech-trained mechanics come to you: at home, work or roadside. Founded from two decades of service excellence by Domex Appliance Services. Call 0330 400 4000.
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