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Ebikes had their origins in modular drive systems that were assembled by enthusiasts and specialty companies choosing their own motors, batteries, battery controllers, motor controllers, and displays. Systems of this kind can offer a high degree of user control and modular repairability.

The landscape has moved away from that model since the mainstreaming of ebikes, and the vast majority in the world are now closed proprietary systems. Each manufacturer has their versions of the above parts and most have sophisticated (compared to the early days) software applications that interface with their parts for setup, diagnostic, and service purposes.

Many ebike drive systems use DRM elements such as manufacturer-supplied dongles and/or passwords to impose various controls or limit software access. In many cases this access is needed to make major changes to the bike, i.e. replacing a broken component.

If one wants to buy or build an ebike today and be assured they will have good control over the use and repair of their property, what does one look for? If one wants to avoid being left with an unusable bike due a drive system manufacturer closing or dropping support, or certain components becoming unavailable, what should one look for? How can a layperson buyer identify what DRM elements in the systems are easy versus impossible or impractical to defeat? What does one give up by prioritizing these factors?

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  • Let's see... How about keeping the owner alive (twitter.com/FDNY/status/1656012965206794245) as a basic parameter of a mutually rewarding long-term connection with said owner? nytimes.com/2023/06/21/nyregion/… Not an answer of course. You're asking an advanced question. Still it's worth noting a much more basic parameter.
    – Sam7919
    Jun 21, 2023 at 18:13
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    @Sam My answer includes that one -- "that have a safe charging system protecting against charging a damaged battery pack and subsequent fire"
    – juhist
    Jun 21, 2023 at 18:19

4 Answers 4

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China has developed an ecosystem of interchangeable parts. While there is typically one proprietary interface (controllers communicating with displays), much of the interconnection is using simple analogue voltages and signals.

For example, a thumb throttle might use a potentiometer emitting 0 to 5V DC voltage to indicate how strongly it is pressed, rather than a digital communication protocol. This can easily be replaced with another thumb throttle from a different manufacturer that uses the same principle.

Typically the interfaces might be:

  • Motor: brushed DC (2 wire) or three phase brushless DC (3 wire, either sensorless or plus hall sensor). You need to buy either a brushed or brushless (BLDC) controller to match the motor you have. Generally any motor will work, with other parameters adjustable in controller settings
  • Display: manufacturer-specific protocol talking to controller
  • Battery: DC voltage (two wires), no communication with BMS. Charging is typically direct into the battery/BMS, not via the controller
  • Gas gauge: voltage-based only, no watt counting (although your BMS may offer that, the controller is unaware. A Bluetooth BMS can be used via its phone app, though)
  • Pedal sensor: torque or cadence, DC voltage based
  • Thumb throttle: DC voltage
  • Brake sensor: dry contact

Here's a picture from a listing for the KT controller: KT pinout

With the exception of the display and the 3-phase motor, every signal there is a DC voltage.

Many Chinese ebikes use this ecosystem. You are free to change out parts as you wish, the main thing is that you change out the controller and display together since that's the only proprietary communication protocol. Typically there are several kinds of displays available for a controller, from simple to fancy. More basic controllers don't have a display and just use DC signalling to the peripherals.

Parts can be found from Chinese sources such as eBay, Aliexpress or importers such as PSWPower. Some examples of manufacturers are:

but other brands and no-brands can be found on Aliexpress.

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    "China" developed these parts? Or did specific companies operating in China?
    – Paul H
    Jun 22, 2023 at 21:32
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    The Chinese ebike market developed this way. I have no idea how it happened, whether it did so organically or via coordination. Jun 22, 2023 at 22:15
  • Thanks for such a great answer! Hopefully this info will be easier to come by in the future. Aug 25, 2023 at 23:41
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Future-proofing can be understood two ways:

  • the user is able to replace broken components by standardized ones.
  • spare parts will be available for the lifespan of the bike, possibly at a cost.

The first one requires the definition of standards, and legislative action to mandate the use of standardized components (or at the very least the interfaces, for example so that a motor from one brand can be replaced by a motor from another brand). As long as these standards do no exist and are not enforced, I don't see a way in that direction, as the bike industry has shown in the past that "creating standards" is the norm rather than the exception. There's maybe one exception though: regular bikes converted into electric ones, as it possible to revert them to regular bikes, or change motor brand - a lack of integration is both an advantage and inconvenient in that case, depending on the priorities.

The second one is basically to go with the dominant successful players in your region, and to count on the network of the service centers or the second-hand market. There may be some regional variation, but in Europe, my impression is that Bosch is the dominant player, Shimano and Emotion/Fazua are present in certain niches (mostly "not too heavy" MTBs and light commuters respectively - although I image that Porsche has other ambitions with Fazua), and brands like Yamaha or Brose are in practice limited to one brand (Giant and Specialized respectively) - of course with online retail, it's to buy exotic brands, but it's very likely that this option will be regretted when the motor will need to be serviced. That being said, big brands can also drop the support of one generation of product after some time (and given bikes can last long, it's likely to happen within the lifespan of the bike).

Otherwise e-bike startups can fail or be bought by larger companies (which is very often followed by a product discontinuation). LBS can also change suppliers, so if future proofing is the criteria, I would not consider brands that are in practice only available from one bike brand, even if it's a major bike brand.

About startups that are selling only a few products with loads of proprietary parts (Cowboy, Vanmoof), that and rely on cloud infrastructure to work, future-proofing is not only an issue for the electric part, but for all components.

But at this stage, my impression is that if future-proofing is the criteria, there are currently rather bets than rules. Some are less unsafe than others, but they remain bets.

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If one wants to buy/build an ebike that is the most future proof as it can get, I would recommend to stay away of the following:

Closed ecosystems

Popular manufacturers of those systems are Shimano, Bosch, Brose, Yamaha , Panasonic, etc. Their development mentality is to control every variable of the systems (hardware, software, user interface, protocol, replacement parts availability, etc) much like Apple does in the tech industry. The advantage is to have a very optimize system, but your are completely tied up when it comes to fixing.

They also do not sell small replacement parts like bearings and tell you that your whole mid-drive motor needs to be replaced when the bearings are worn-out (which will happen, they are bearings!).

For some of them like Bosch, you also need to attend their certification course (only available to authorized bike shops) to even have access to their diagnostic probe and software.

Mid-drive motors

Most of the mid-drive motors need a frame with specific mount points. Those mounts points are not standardized so if you buy an ebike with a Shimano system and want to swap it later for a Bosch one, you can't. Even within the same brand, the mount points can change between generations.

Some mid-drive motors can be installed on a regular bottom bracket shell (e.g. Bafang), so those would be to prioritize if one wants to go the mid-drive way.

Custom-shaped battery packs

Even if an ebike uses a more open ebike system (i.e. mostly Chinese brands), the battery pack enclosure could be custom made for the specific bike model so it can, for example, fit inside the downtube (semi-integrated or integrated). If the pack goes bad and you need a replacement, you are totally dependant on the bike manufacturer.

One can of course go to a company that can replace the Li-Ion cells, but if the BMS is fried, things get harder. It is better to prioritize ebikes with the battery mounted on a rear rack or using the water bottle cage holes.

OEM parts

Even if an ebike uses open components, it does not mean you can buy them. Some of those components are OEM parts, which means the parts manufacturer (e.g. Bafang) will only sell them to bike manufacturers that get them in large quantity and not to bike shops. This make finding a replacement very hard and will often lead to replacing the controller/lcd/wiring combo (and something even the torque sensor which output signals are less standardized than the throttle for example).

Re-branded parts

Some ebike manufacturers will re-brand third-party ebike parts to put their name on. For example, we can recognize that RadPower uses the King-Meter SW-LCD. The thing is, we do not know if they ask King-Meter to put a custom firmware inside or to change the connector type making the original LCD incompatible. We would then need to rely on the bike manufacturer to get a replacement instead of the part manufacturer, which is a less reliable source.

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I think by far the most important ability is the ability to re-cell a battery pack, since battery packs wear out even if left unused. The cells almost always are standard quality cells from for example LG, Panasonic or Samsung.

However, this does not necessarily preclude using systems with DRM. For example, Bosch battery packs can be re-celled simply by providing power to them at all times. So there must be an external power supply during the re-celling operation. If power is interrupted only for a brief moment, the battery pack is bricked. There are companies that have the skills to re-cell Bosch packs.

I think ideally one should prefer systems where the pack can be opened by standard tools and it's a matter of simple soldering to re-cell, but how on Earth does one find such a system? Probably all of the quality mid-drive systems where one can expect the components to last for a long time, that have good control software (so that the drive assist doesn't feel jerky), that have a safe charging system protecting against charging a damaged battery pack and subsequent fire, and that have enough torque to be actually useful, are the DRM systems by Bosch and similar companies (Yamaha, Shimano, maybe I'm forgetting something here?).

In practice, recelling is often more expensive than simply buying a new pack, since the labor needs to be priced in too. The manufacturers know this and price the battery packs at maybe five times what an equivalent electric vehicle pack would cost. However, on old bikes that may be the only possibility to fix an otherwise unusable bike. So usually it makes sense to buy new packs as long as they are available, and switch to re-celling once packs become unavailable.

It's true that there's a danger of something becoming damaged or stolen on a very old bike, thus making it unusable since replacement parts may not be available. I would say it makes sense to prefer systems that require tools to steal something, rather than systems where the defense against stealing is simply expecting the cyclist to remove the bike computer when parking the bike.

The DRM is annoying as hell. I can't re-program the wheel diameter to my bike. I understand this is intended to make it harder to "tune" the bike (by changing assist cut-off speed from 25 km/h to for example 26 km/h by slightly altering the wheel diameter), but it makes simple operations like swapping to a different type of tire sacrifice speed.

An ebike that one actually uses is far better than an ebike one doesn't use because it feels so powerless, jerky, slow or dangerous due to lack of lights. Thus, the absolute minimum features are:

  • Mid-drive
  • Lots of torque
  • Good control software that makes the assist feel natural rather than jerky
  • A clutch that disables the drive system once speed exceeds 25 km/h, or else the ebike can actually be slower than an equivalent non-ebike
  • Ability to attach lights powered by the ebike battery

Using major Western brands is advisable. If some brand has more market share, it's always a better choice since the manufacturer is less likely to exit the ebike drive system market.

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  • 7
    For years I stuck to recommending Bosch and Shimano because of what I presumed was the probability that they would be bulwarks of long-term support. After seeing how Bosch has completely abandoned support for their first generation system, I've been re-evaluating. Some of those bikes are now bricked without various kinds of hacky cottage industry support. Meanwhile I've heard tell that Bafang systems (hub and mid-drive but moreso hub) are structurally pretty close to modular systems, which I have perhaps seen bear out a little in the ease of some component swaps I've done on them. Jun 21, 2023 at 22:44
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    I beg to differ. Depending on the indended use, and your surroundings, a mid- or a rear-wheel-drive might be more suitable. And i would strongly recommend NOT focussing on western brands. The chinese, as @NathanKnutson pointed out, are looking a lot more modular and open.
    – Burki
    Jun 22, 2023 at 8:53

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