Choosing the right transmission for your e-bike is crucial for a smooth and enjoyable ride.
The transmission (or gear system) manages how power from your legs and the motor translates into speed and torque. In a nutshell, you have a choice between traditional derailleur gears, modern internal gear hubs, or even going single-speed.
Each has its own strengths. The key is to match the gear system to your riding style, terrain, and maintenance preferences so your ebike works with you, not against you.
Featured Summary
-
Derailleur Gear Systems: A common external gearing setup with multiple sprockets and a chain derailleur. They offer a wide gear range (great for hills and speed), lighter weight, and high mechanical efficiency. However, derailleurs are exposed to the elements and require regular cleaning, tuning, and component replacements (chain, cogs) to stay smooth. Best for riders who demand performance and don’t mind a bit of upkeep.
-
Internal Gear Hubs (IGH): An enclosed gearing system built into the rear wheel hub. IGHs provide low maintenance and allow shifting even while stopped, which is a big plus for city riding. They keep the drivetrain protected from dirt and weather, reducing wear and tear. Downsides: IGHs are usually heavier and costlier, and might not offer as wide a gear range as a derailleur setup. Ideal for those who value reliability and clean looks over saving a pound of weight. (If you want a quiet belt drive e-bike with no chain oil, an IGH is essentially required.)
-
Single-Speed (No Gears): A simple option with a single gear ratio and no shifting mechanisms. This keeps the bike light and ultra low-maintenance, and it’s very beginner-friendly. The e-bike’s motor helps compensate for the lack of gears on hills or high speeds. Single-speeds work best for urban commutes or flat terrain. But on hilly routes or if you want to pedal efficiently at varied speeds, you’ll quickly feel the limitations. It’s a trade-off between simplicity and versatility.
Understanding E-Bike Transmissions (Gear Systems)
Before diving into which to choose, let’s clarify what an e-bike transmission actually is.
In essence, it’s the bike’s gear system – the set of components that adjusts how hard or easy it is to pedal. Just like a car’s transmission changes gear ratios to optimize engine power, an e-bike’s gears optimize human and motor power for different situations.
On a traditional bicycle, gears let you maintain a comfortable pedaling cadence whether you’re climbing a steep hill or sprinting on flat ground.
On an e-bike, the gear system serves the same purpose for both you and the electric motor. Even with electric assist, you’ll want the right gear: lower gears make climbing hills or starting from a stop easier (providing more torque but lower speed), while higher gears allow faster speeds on flats or downhills.
Think of it as finding the right balance between your pedaling effort and the motor’s assistance for any given moment.
Do you even need gears on an e-bike? For most riders, the answer is yes. The motor doesn’t entirely replace gears.
In fact, many e-bikes (especially those with mid-drive motors) rely on the gears to keep the motor in its optimal RPM range.
Using the proper gear not only improves your pedaling comfort, but also can extend your battery range by letting the motor work more efficiently.
Some simple e-bikes do fine with one gear (as we noted, single-speeds are a viable choice for flat areas or short trips), but if you encounter varied terrain or longer rides, a geared transmission is invaluable.
Types of E-Bike Transmissions: Derailleur vs. Hub Gears vs. Single-Speed
E-bike transmissions come in a few flavors. Let’s break down the main types of gear systems you’ll encounter, and how each one works.
Derailleur Gear Systems (External Multi-Speed)
An example of a derailleur gear system on an e-bike. This fat-tire electric bike uses a rear hub motor combined with a multi-speed derailleur drivetrain (cassette and chain), offering a wide range of gears for different speeds and climbs.
The derailleur system is the classic bicycle gearing you’ve likely seen on regular bikes. It consists of a set of sprockets (the cassette) on the rear wheel, and often one or more chainrings at the pedals, all linked by a chain.
A rear derailleur mechanism moves the chain from one sprocket to another to change gears (and a front derailleur can shift between chainrings, though most e-bikes use a single front chainring for simplicity).
When you click your shifter, a cable pulls the derailleur, guiding the chain onto a different cog – literally “derailing” the chain to a new gear.
Advantages of Derailleur Systems
Derailleur setups typically offer a wider gear range than internal hubs, especially if paired with multiple chainrings.
This means you get both very low gears for steep hills and high gears for fast cruising. They also tend to be lighter in weight than hub gear systems, which can make the bike a bit more nimble.
Derailleurs are known for efficient power transfer – there’s minimal energy loss when the chain is running straight on a sprocket, so these systems can feel slightly more efficient (and may give a small boost to battery range) compared to some internal hubs.
Another plus: derailleur parts (cassettes, chains, derailleurs themselves) are widely available and generally cheaper to buy or replace, keeping initial bike costs and repair costs lower.
Because everything is external and standard, DIY enthusiasts appreciate derailleur systems for their flexibility – you can easily swap cassettes or chainrings to change your bike’s gearing.
For example, if you build a custom e-bike and want more torque for hill-climbing, you might install a smaller chainring or a larger cassette sprocket. This kind of tinkering is straightforward with derailleur drivetrains.
Disadvantages of Derailleur Systems
The very fact that derailleurs are exposed is also their Achilles’ heel. Mud, dust, rain, and road grime can gunk up the gears and chain. You’ll need to clean and lubricate the chain and derailleur regularly for smooth shifting.
The system can go out of adjustment and require tuning (that’s why bikes sometimes start mis-shifting and need a trip to the shop or a DIY tune-up of the derailleur screws and cable tension).
Additionally, the derailleur mechanism hangs low on the bike and can be vulnerable to impacts – a hefty knock on a rock or curb can bend it. It doesn’t happen often with normal riding, but it’s a risk, particularly for off-road e-bikes.
Another limitation: derailleurs generally can’t shift when you’re not pedaling. They require the chain to be moving under tension to hop between gears.
If you forget to downshift before stopping at a red light, you’ll have to do the awkward pedal push-off in a high gear or manually shift while slowly turning the pedals.
And while you can shift under load (since e-bike motors often keep turning the chain), it’s best to ease off pedaling or throttle when shifting; dumping full motor power while changing gears can lead to clunky shifts or even chain/gear damage.
High-torque mid-drive e-bikes in particular can stress the chain and cogs during shifts, so learn to feather your power during gear changes for longevity.
Lastly, derailleur setups do experience faster wear on e-bikes. The motor’s power means the chain and sprockets are under higher forces than normal, so they might stretch or wear out about 30% faster than on a regular bicycle.
You’ll need to check and replace the chain and cassette periodically to maintain optimal performance. The good news is those parts are relatively inexpensive.
Internal Gear Hub Systems (Enclosed Gears)
A close-up of an internal gear hub on an e-bike (Shimano Alfine 8-speed), paired with a Gates belt drive instead of a chain. All the gears are sealed inside the hub shell, offering a clean look and protection from the elements.
Internal gear hubs (IGH) house the entire gear mechanism inside the rear wheel’s hub. Instead of derailing a chain across external sprockets, an IGH uses a set of planetary gears inside a sealed casing.
Shifting gears engages different gear ratios inside the hub. From the outside, you just see one front chainring, one rear sprocket, and no derailleurs – a very sleek, simple appearance.
Advantages of Internal Hubs
The biggest appeal is low maintenance and high durability. Since all those gears are tucked away from dirt and moisture, they aren’t getting contaminated or rusty easily. You can ride for thousands of miles with minimal upkeep – no constant cleaning or frequent adjustments needed.
The chain (or belt) on an IGH bike doesn’t have to move side-to-side across gears, so it wears more slowly too. For daily commuters or all-weather riders, an IGH means less time in the garage and more time on the road.
Another huge plus: you can shift while stationary or coasting.
Ever struggle to get going after stopping in a high gear? With many internal hubs, you can click down to an easier gear while you’re at a stoplight, without pedaling. When the light turns green, you pedal off with ease.
IGH bikes are excellent for stop-and-go city riding because of this. You can also often shift multiple gears in one twist of the shifter, even jump from high to low in one go, which some find convenient for sudden terrain changes or stops.
The enclosed system also gives a clean look – no dangly derailleur or big cassette on the wheel. It’s a tidy aesthetic that many riders love.
If you pair it with a belt drive instead of a chain, you eliminate chain grease and noise entirely. Belt-driven IGH e-bikes run almost silently and you’ll never get chain grease on your pants (plus belts last a long time).
In fact, if you dream of a belt-drive e-bike, a hub gear is the way to go, as derailleur systems are incompatible with belts.
Additionally, internal hubs are generally very robust and reliable. There’s a reason they’re popular on bike-share fleets and city bikes – they’re hard to mess up.
There’s no delicate hanger to bend, and the internal parts are engineered to handle years of use. Many e-cargo bikes use IGH because they can handle the constant load and require little care, which is perfect for delivery or family bikes that need to just work every day.
Disadvantages of Internal Hubs
The trade-offs for all that convenience come in the form of weight and cost. An IGH unit weighs more than a derailleur and cassette.
If you compare similar level components, your bike might be a kilogram heavier with a hub gear instead of a derailleur. On an electric bike, the extra weight is often less noticeable (the motor helps negate it), but it still slightly affects handling and lifting the bike.
High-quality internal hubs (like the famed Rohloff 14-speed or Shimano’s Alfine series) can be quite expensive, which pushes up the price of any e-bike equipped with them.
IGHs also have a limited gear range relative to the very widest derailleur setups. Mid-range hubs might have 3, 5, or 7 speeds, which cover moderate terrain but not extreme hills.
Even the better hubs (8-speed, 11-speed, 14-speed) have improved range (some up to ~400–500% range between lowest and highest gear), yet a derailleur with a wide cassette can exceed that range.
For most riding you won’t feel short-changed, but hardcore mountain bikers or speed demons might.
There is also a touch of efficiency loss in some internal hubs. As the power transmits through multiple gears inside, friction can eat a few percent of efficiency compared to a clean derailleur drivetrain.
Modern hubs are pretty good – the difference isn’t huge, and in practice many riders won’t notice a big drag. But if maximizing battery range or sprint efficiency is your obsession, a derailleur still has the edge.
Another consideration: fixing or servicing an IGH is not typically a do-it-yourself job for most riders.
While problems are rare, if something internally goes wrong, you’ll likely need a specialist or to send the hub in for service. By contrast, with derailleurs, any bike shop (or a handy DIY rider) can replace a bent hanger or broken derailleur fairly easily.
Also, removing the rear wheel on an IGH bike can be more fiddly – you usually have to disconnect a shift cable (and possibly brake linkage if it has an integrated coaster brake) before the wheel comes off, making flat repairs slightly more involved.
Finally, not all internal hubs are equal. Cheaper 3-speed hubs (like those old vintage bikes) might struggle on big hills or under high torque.
Many hub gears also don’t appreciate heavy torque while shifting – you often should ease up pedaling for a moment when changing gears, or some hubs could clunk or wear.
(Some newer designs like the Enviolo continuously variable hub are built to handle shifting under load more gracefully, and even offer automatic shifting – technology is improving rapidly here.)
For most riders, these are minor learning curve issues and not dealbreakers, but it’s worth noting that shifting under full power is not recommended with hub gears – you get used to backing off a touch when you twist that shifter, which becomes second nature.
Recommended: Electric Bicycle Tire Pressure [Getting Started Guide]
Single-Speed and Other Alternatives
Not every e-bike uses a multi-gear transmission. Some are single-speed, meaning there’s just one gear ratio and no gear shifters at all.
These bikes trade versatility for simplicity. With a capable motor, a single-speed e-bike can still be practical: you rely on the motor’s different assist levels to help on hills or to go faster, rather than shifting gears.
Many urban e-bikes and inexpensive models go this route to keep things user-friendly. As one e-bike maker quips, if you don’t have gears, you never have to worry about what gear you’re in!
A single-speed e-bike will typically be lighter and cheaper, since it has fewer components (no shifters, derailleurs, or multiple sprockets).
It’s also virtually maintenance-free — with no shifting parts to adjust, you mostly just keep the chain (or belt) clean and tensioned.
For flat city riding, single-speeds work great: you get a clean, quiet ride and can always use high motor assist if a rare hill comes up.
Rental and bike-share electric bikes often use single-speeds combined with powerful motors for exactly this reason: it’s foolproof for any rider.
However, the limitation is obvious when you hit varied terrain. Without lower gears, climbing steep hills means you’re either straining hard or heavily reliant on the motor (draining the battery faster).
Without higher gears, you might spin out (pedal very fast with no resistance) at speeds above maybe 20–25 mph, making it hard to contribute pedaling beyond the motor’s assist limit.
If you plan to tackle hilly country or want efficient long-distance pedaling, a single-speed could leave you wanting more.
There are also some niche transmission technologies out there: for example, continuously variable transmission (CVT) hubs like the Enviolo, which don’t have set gears at all but rather a seamless range you can dial in.
Some e-bikes even have automatic shifting systems that change gear for you based on speed or cadence (certain hub gear models offer this, as do some exotic automatic derailleur systems).
These are specialized solutions usually found on higher-end models aimed at maximizing comfort.
They’re beyond the scope of most riders’ decisions, but keep in mind the e-bike world is evolving – the classic derailleur vs. hub gear debate might one day include smart auto-shifters as well!
Recommended: What’s Considered High Miles on an Electric Bike? Here’s the Truth
Matching Your Transmission to Your Riding Needs
Now that we’ve covered the options, how do you decide which transmission is right for you? It boils down to your riding needs, style, and priorities.
Let’s explore a few common scenarios and what gear system tends to fit best:
City Commuting and Casual Riding
If you use your e-bike for daily commutes, errands, and leisure rides on mostly flat to moderate terrain, convenience and low upkeep might be your top priorities.
In this case, an internal gear hub or even a single-speed could be your best friend. City riders often face lots of stop-and-go traffic lights, meaning the ability to shift to a easy gear while stopped (only possible with an IGH) is a major perk.
The weatherproof, low-maintenance nature of hub gears also shines here – you can ride through rain and road grit without immediately needing to degrease your drivetrain.
For example, a commuter e-bike with a 7-speed internal hub allows you to effortlessly handle occasional hills and headwinds, yet you’ll hardly ever need to adjust anything or deal with a dropped chain.
If your route is pancake-flat and short, a single-speed e-bike kept in a medium gear plus electric assist might suffice as well (and will be very quiet, especially with a belt drive).
The key question: Do you value a hassle-free experience more than absolute efficiency? If yes, lean toward an IGH or single-speed.
Many urban e-bikes are designed exactly for that “get on and go” ease – for instance, brands often spec an internal hub with a belt so commuters can just ride daily without cracking open a tool kit for years.
The trade-off of extra weight or cost is usually worth the time saved on maintenance for these users.
Recommended: The Durability and Maintenance of Shimano 7-Speed Systems
Off-Road and Mountain Trail Riding
For e-MTBs (electric mountain bikes) and trail riding, performance and gear range usually trump other concerns.
Off-road riders encounter steep climbs, rapid terrain changes, and the need for precise control. Here, derailleur systems still dominate.
They provide a wide range of gears which is crucial for handling everything from a tough uphill rock garden to a high-speed downhill sprint. They’re also lighter, which helps when maneuvering the bike over logs or jumps.
Mountain bikers tend to be more tolerant of maintenance (it comes with the territory of beating up your bike in mud and dust).
Plus, on a trail, if something does go wrong, derailleurs are easier to jury-rig or tweak trailside than internal hubs.
Almost all high-end e-MTBs use derailleur drivetrains, often 10, 11, or 12-speed setups, sometimes with special e-bike chains that withstand higher torque.
The efficiency of derailleur gears is also a boon on long trail rides – you want as much of your leg power and battery power going into moving the bike as possible when you’re far from home base.
While internal hubs exist that can handle off-road (the Rohloff Speedhub 14-speed is legendary among expedition cyclists for instance), they are very expensive and still relatively uncommon on mountain bikes due to weight.
There are a few niche e-MTBs that use IGH + belt for low maintenance in muddy conditions, but unless you specifically seek that, you’re likely looking at a derailleur system for any serious trail e-bike.
High-Speed and Long-Distance Riding
If you’re a road e-bike rider, a gravel adventurer, or anyone who regularly hits higher speeds and covers long distances, you will benefit from the efficiency and fine-tuned gearing of a derailleur system.
Road-oriented e-bikes often come with derailleur setups because they allow finer gear gradation, which means you can always find a perfect cadence.
At 25+ mph (for speed pedelecs or when pedaling beyond assist), a derailleur with a high gear is helpful so you’re not “spinning out.”
Likewise, if you ever ride with the motor off or in Eco mode to extend range, having a broad selection of gears makes the bike more versatile under pure human power.
That’s not to say an internal hub can’t do distance – many touring bikes use Rohloff hubs, valued for their robustness on long journeys.
But on e-bikes, the majority of fast or distance-oriented models lean derailleur for that slight edge in weight and efficiency.
Derailleurs also make it easy to adjust your gearing for different conditions (swap to a bigger cassette if you plan a trip to the mountains, for example).
However, one scenario where an internal hub could appeal in long-distance or trekking use is reliability in harsh conditions.
If you’re e-biking across a desert or through a rainy week-long tour, not worrying about clogging your derailleur with sand or mud has advantages.
Some adventurous riders choose IGH for that peace of mind, accepting the efficiency loss. It really comes down to how extreme your rides are and whether you favor performance vs maintenance-free consistency.
Recommended: Torque Sensors in E-Bikes: Your Complete FAQ Guide for Smoother Rides
Cargo Hauling and Heavy Duty Use
For cargo e-bikes, family e-bikes carrying kids, or any situation with extra weight and strain, durability and torque handling are key.
This is almost a split decision: many cargo e-bikes use internal hubs (often with belts) because they’re robust and low-maintenance for daily utility use – the last thing you want is a delivery bike whose derailleur got bent in a parking lot mishap.
Being able to shift while stopped is also invaluable when you have a heavy load and need to get moving from standstill (imagine a loaded cargo bike at a red light – with a hub gear you can click into an easy gear before accelerating that weight).
On the other hand, very heavy loads and powerful motors can put a lot of stress on internal hubs.
If the e-bike has a high-torque mid-drive motor (common in cargo bikes), it can potentially strain or even damage some IGHs if used carelessly.
In these cases, either the bike will use a specially robust hub (like the Rohloff or Enviolo heavy-duty models), or it might stick to a derailleur which, while it wears out chains faster, is cheap to replace when it does.
As a user, if you’re pushing the limits of carrying capacity or using a tuned high-power setup, you might lean towards a derailleur system or only the most proven heavy-duty hub gears.
In summary, for utility bikes that prioritize ease of use and longevity, an IGH (especially paired with a belt drive and maybe even automatic shifting) is a fantastic choice.
For raw pulling power and serviceability under extreme use, a derailleur can still be a pragmatic option (with the understanding you’ll replace the chain and sprockets more frequently due to the extra load).
Budget and DIY Considerations
We can’t forget the practical aspect of budget. If you’re shopping for an e-bike (or building one) on a tight budget, derailleur-equipped bikes tend to be more affordable.
You’ll find plenty of reasonably priced e-bikes with a simple 7-speed or 8-speed derailleur that do the job.
Internal gear hubs, being more complex, usually appear on pricier models. Similarly, a DIY e-bike builder converting a standard bike will often stick with the bike’s existing derailleur gears because it’s the economical route – you likely already have them on the bike, and they mesh right up with a mid-drive motor kit or hub motor setup.
This brings us to DIY enthusiasts and gear choice in more detail.
Special Considerations for DIY E-Bike Builders
If you’re building or modifying your own e-bike, choosing the right transmission requires a bit of extra thought.
DIY builds often use aftermarket mid-drive motors (like Bafang kits) or hub motor kits installed on regular bikes. Here’s what to keep in mind:
Compatibility
Most off-the-shelf conversion kits assume a standard derailleur drivetrain.
For example, a mid-drive motor kit will usually mount at the crank and drive your chain, working with your rear gears. These kits often work best with an 8, 9, or 10-speed cassette (derailleur system).
If your donor bike has an internal hub, it can sometimes still work, but you must ensure the motor’s output cog aligns with the IGH sprocket and that the hub can handle the motor’s torque.
Be aware that some internal hubs are not designed for the stresses a powerful e-bike motor can put on them.
Torque and Hub Strength
A general rule in the e-bike community is that if you’re running under 500 watts, most quality internal gear hubs will cope fine.
But when you get into high-power builds (750W, 1000W and beyond), you risk overloading the internal hub gears.
The sudden jolt of a strong motor in a high gear can damage IGHs not rated for that power. People have had good success with top-end hubs like the Rohloff or the enviolo (Nuvinci) in higher power setups, but those parts are pricey.
For mid-range hubs like Shimano Nexus/Alfine, 750W is about the upper comfort limit in practice – and even then you must use good shifting technique (ease off power when shifting) to avoid problems.
If you’re a DIY builder planning a very powerful e-bike, a traditional derailleur may actually last longer (even though you’ll go through chains faster) because there are fewer delicate internal parts to break.
Maintenance and Tinkering
Many DIY folks don’t mind maintenance – in fact, you might enjoy tweaking your bike.
A derailleur system offers a lot of tweakability. You can change gear ratios easily by swapping cassettes, adjust the derailleur stops and indexing to perfection, or replace parts piecemeal on a budget.
Internal hubs are more “set and forget,” which is great if you don’t want to fuss with gears, but less engaging if you love to fine-tune.
Also, if an internal hub does need service, it’s often not DIY-friendly (special tools and knowledge are required to open a hub gearbox). Keep that in mind if you live in an area without bike shops familiar with IGHs.
Custom Builds (Chain vs. Belt)
Some garage builders are enticed by belt drive conversions for utter silence and cleanliness.
If you want to do a belt on your DIY e-bike, you’ll have to use an internal gear hub or a single-speed setup.
Converting a frame to belt drive can be non-trivial (the frame needs a break in the rear triangle to slip a belt in, or an adjustable dropout for belt tension).
It might even dictate your frame choice. This is an advanced project consideration, but worth noting: the transmission you choose (hub vs derailleur) could affect other design choices in a custom build.
Overall, DIY enthusiasts should choose a transmission that matches their technical comfort level and the performance of their build.
If you’re converting a basic commuter and want it to be bulletproof, you could opt for an internal hub wheel for low maintenance.
If you’re hot-rodding a high-speed e-bike, a derailleur with readily replaceable parts might be the prudent choice.
And if you’re modding a bike for fun and learning, starting with the good old derailleur setup is recommended – it’s simply easier to work on and there are countless resources online for troubleshooting it, whereas internal hubs are a bit of a black box.
Conclusion
In the end, “Which transmission should I choose?” doesn’t have a one-size-fits-all answer – it depends on you. The right e-bike transmission is the one that best aligns with your riding conditions and how much tinkering you’re willing to do.
Finally, think about the experience you want: Do you enjoy feeling the precise click of gears and being in tune with your bike’s mechanics? Or do you prefer a seamless ride where you hardly think about gears at all?
Answer that, and you’re halfway to your decision. Whichever transmission you choose, it should enhance your e-bike journeys by making pedaling feel natural and empowering. Happy riding, and may you find the gear system that keeps you smiling mile after mile!
