Motors, batteries and standardisation | What’s next for e-MTBs?

Remember when e-MTBs looked like DIY jobs with a motor and battery crudely bolted onto existing frames? This is quite a contrast from some of the latest models like the Scott Lumen, Trek Fuel EXe, Santa Cruz Heckler SL and Focus VAM² that could just about pass as analogue mountain bikes, until you look closely.

Only a few years ago if you’d said that we’d be toying with the 15kg mark for a pedal assist mountain bike, we’d have laughed in your face, but that has become a reality. Same goes for fully integrated systems that can shift for you, regardless of whether you’re pedalling.

But where are things headed, and where is there still room to improve? We posed that question to Daniel Theil, TQ’s Product Manager who has been with the brand since the e-MTB wing only had two employees — now there are 120 people.


The e-Bike wing of TQ is only a small part of the tech that the German outfit produces. TQ also makes motors and electronics for aviation, medical, optoelectronics, shipping, and industrial applications.

But I feel the bigger trend is to bring the power bikes, kind of closer to the SL.

SL vs Full Power

Two pretty distinct categories of e-MTB have emerged over the past couple of years, light and nimble SL bikes like the Fuel EXe, the Specialized Levo SL and the Scott Voltage, and the full-fat options like the Orbea Wild, the Pivot Shuttle AM, and Canyon Spectral:On to name a few.

But then there is a bit of a sub-category between the two with bikes like the Giant Trance X Advance E+, Cannondale Moterra and the Orbea Rise, which see a full power motor (in the case of the Rise that has been de-tuned) and small battery splitting the difference between full power and SL.

While it’s still in the early days, Theil believes that we will see the two categories continue to converge.

Theil believes that full power and SL e-MTBs will continue to converge, and even the beastly full fat options will become quieter, lighter and more sleek.

“The big motor, small battery is making best use of what’s out there,” he says. “It’s not ideal, just a different interpretation, a different niche they are aiming at.”

With that said, he also pointed to SRAM’s Powertrain drive system as evidence that full power e-MTBs aren’t going anywhere.

“The SRAM Powertrain system they launched, it’s not very SL-ish. It’s still a very beastly e-Bike. So there’s definitely that, and like the 900Wh batteries,” he says. “But I feel the bigger trend is to bring the power bikes, kind of closer to the SL. Make them lighter, make them more sleek, and integrated. Make them quieter for sure.”

As an example of this he pointed to the latest iteration of the Orbea Wild, which we reviewed back in October, which sees a 750Wh battery that’s not removable. Theil notes that this not only saves weight, but it also makes the downtube look a bit sleeker. He expects this type of blending and borrowing of weight-saving techniques we often see on SL e-MTBs to become more common among the full power options.

Maybe if we have SL bikes that are 13kg or something, maybe we can call it a day…I think there’s definitely potential to move both categories into a lighter, more integrated space.

As it stands, there is about a 5kg gap between the two categories, and Theil believes there is still quite a bit to be made up for both.

“Maybe if we have SL bikes that are 13kg or something, maybe we can call it a day, and we don’t have to become even lighter. But until then, I think there’s definitely potential to move both categories into a lighter, more integrated space,” he says.

Battery tech and capacity

Every week, there is a big news story about a new battery technology or cell chemistry that was discovered, which is pegged to change the world. With the focus on green energy and moving away from fossil fuels, battery technology will be — and already is — an area of innovation at insane speed.

While Theil and TQ are up to speed on all of this, he says it will be some time before any of that new technology makes its way into an e-MTB.

“They’re definitely improving, and you can read in the newspapers about this new cell chemistry that was found, and it’s going to change the world. But then you have to be honest. First, it’s going to get into electric cars and the big numbers where the big money is at, and then someday it will trickle down into e-Bikes,” he says

The Norco Sight VLT has the option for 900Wh battery. That is a tonne of range, that most people will struggle to drain in one ride.

“The amount of cells we need is so small compared to electric cars, and that puts us pretty low on the priority list of the cell manufacturers,” he continues.

Even still, there are things happening with e-MTB batteries, like the 5.8Ah cell. The standard size for a battery cell used in an e-MTB is 21mm in diameter and 70mm long. Previously these could only store 5Ah, but have jumped to 5.8, which is about a 15% increase in capacity.

I think we have understood how much (capacity) we need, and most people have a really hard time draining such a big battery.

Some brands are experimenting with new chemistry and solid state options, however Theil tells us the main gains there would be faster charging or creating a safer, more stable battery. While we wait for the next significant innovation in technology to trickle down, he says the most immediate improvements will come from being smarter with the layout of the cells and trying to make the entire unit more compact to better match the shape of the frame.

The battery is one of the heaviest parts of an e-MTB, and a bit of rough, back-of-the-napkin math shows you get about 200-250Wh/Kg. Where all that weight is placed in the bike can have a significant impact on the way the bike rides — if there are a couple of kilos hanging out up near the head tube, the bike is going to ride like garbage. To put it simply, the larger the battery, the higher it creeps in the downtube.

While we’ve seen the energy capacity arms race stall out at 900Wh for the time being, Theil believes that someone will release a 1,000Wh battery for the sake of the unique selling point. But he also thinks the negatives of the cost, weight and size outweigh the extra capacity.

“I think we have understood how much (capacity) we need, and most people have a really hard time draining such a big battery,” he says.

Rather than go bigger, Theil thinks the next thing will be reducing the size and weight of the battery packs and improving modularity to make it more feasible to swap batteries out based on how big a ride you’re planning.

In the Spectral:ON, Canyon re-oriented the cells in the battery pack to make it more compact. According to Theil this is the type of immediate action brands can take to make for significant improvements to the weight of bikes and where it sits in the frame.

Matching motors to legs for max efficiency

Every e-Bike has an electric motor and some form of synchronisation gears, because electric motors spin fast — we’re talking thousands of RPM. Whereas humans tend to prefer a cadence down in the double digits, so the reduction gears are needed to match that fast-spinning motor and the slow-spinning human.

“Electric motors inside e-Bikes are pretty similar. They’ve been around for so long, they’re pretty well engineered, and you could fight for a few per cent of efficiency here and there, or make them a little lighter or more compact. But that’s not the big change, the big change is the gearing, and that’s why our motor is round and small, and others are kind of egg-shaped and bigger,” he says.

It’s these synchronisation gears that create the cadence sweet spot where you can get the maximum performance out of the motor. For many systems, this sweet spot seems to be somewhere between 80-90 RPM, which is an achievable cadence just spinning along — but mountain biking is rarely just spinning along.

Every e-MTB motor has a cadence sweet spot where you can extract the max performance out of the drivesystem. Sometimes it can be difficult to hit that sweet spot when you need it most.

“I think we need to try and stretch the sweet spot. Because even if your happy cadence is around 85, there will always be situations when you’re stuck in the wrong gear, or because it was too steep or you have to tackle some steep ledge,” he says

“That’s where the motor ideally has a wider bandwidth of a good efficient sweet spot. So if you’re stuck in one of those situations, you’re not punished that much,” says Theil.

To achieve that, he says, ultimately, that comes down to the design of the electric motor itself, that is, designed for the purpose and matching that with similarly purpose-engineered gearing rather than potentially adapting something off the shelf.

That added efficiency and extraction of maximum performance out of the motor also comes to the heat management. Of course, the existence of the heat is a byproduct of system inefficiency, and it’s something that has to be managed within an e-MTB, not just for performance, but there are also rules around the maximum temperature of parts deemed to be touch surfaces.

According to Theil, maximising performance here again comes from the motor manufacturers exploring different options to create the most fit-for-purpose combinations for batteries and drive units.

The synchronisation gears are the reason that most e-MTB motors are so big, and finding a way to keep them quiet and efficient without adding too much size and weight is quite a balancing act.

“It’s always a balance, and there is no perfect cell for every application. A smaller motor will have less of a peak power demand, so you can use different cells that offer more capacity, so you get more range out of the same battery weight and size. A bigger motor will need a cell that is more capable of delivering high peak power, but will have less capacity because it is fine-tuned in a different direction,” he says.

Theil explains some of this also comes down to the software controlling the bike. Especially when it comes to adaptive riding modes, the key is for everything to be intuitive, so don’t actually realise how well everything works until you ride something else.

I think as a first step, and a big step is to find standardisation on parts that are wear parts.

He tells Flow that in the TQ motors, they can get a ballpark on how much you weigh and determine if you’re riding flats or clips after a few pedal strokes among other things.

“We can see the average power you’re putting down, and we can say, okay, where is your comfort zone, and now where is the rider really going out of their comfort zone,” he says.

The software that controls an e-Bike system is key to how it reacts to your inputs, there is always room to improve to make the experience more intuitive.

“A lighter rider coming out of their comfort zone might be 150 watts, and for a heavier rider going out of the comfort zone might be 300 watts, so the motor has to react differently.

The motor should go with you. It’s what makes e-bikes really exciting. It’s like the first real blend of motor and human. On a motorbike, you have a throttle and tell the machine what to do. And then an e-Bike it really blends in, the electric motor reacts to what you’re doing,” he says.

E-MTB parts

When we asked the folks from Merida to look into the crystal ball about where e-MTBs were headed, they mused that we might see development in terms of the components boiled onto electric mountain bikes.

In the last couple of years, there has been a brand new segment of e-MTB-specific parts that has emerged. Ranging from drivetrain components like Shimano’s LinkGluide to tyres like the Maxxis E-50 tyres, and DT Swiss’ Hybrid (yes, confusing name) e-MTB wheels and hubs.

Shimano’s LinkGlide is a heavy duty groupset aiming to maximise longevity but it does add some weight.

“Oftentimes the “E” tag components are just a little bit heavier — you take the enduro wheels and make them the e-Trail wheels — it doesn’t really seem like there is much research going into that,” he says.

For example, the Maxxis E-50 tyres aren’t any different structurally from those of the same casing and compound that don’t have that logo on the side wall. It just signifies that the tyre model has undergone an additional testing protocol. However, there are instances where e-specific components actually make a lot of sense.

“More components are being electrified, so it’s the logical next step to bring them into the ecosystem. For example, electric dropper posts — why do they still need their own battery? Why don’t they have a little cable coming off the bottom, and they’re just hooked up to the system?” muses Theil.

On the one side, they tried to create USPs for their system, and on the other side, they still make their money selling drivetrains. If one of them opens up, then it’s a really nice chance for them to steal quantities for the other one.

The Maxxis E-50 tyres are no different to those that don’t bear this symbol on the hot patch. It simply means that tyre has undergone an extra bit of testing.

This is something that’s already commonly done with electronic drivetrain components. Theil says the litmus test for an “E” component is that it needs to answer the question: what do I want to solve with it, and what benefit does it give to the rider? Regardless of your take on electronic dropper posts, having one less battery to worry about is positive.

If that case for adding an e-Component doesn’t have a good answer to these questions, Theil says you can probably write it off as marketing bull dust.

Integration and standardisation

With the latest e-MTB offerings from Shimano and SRAM, each features a version of auto and coast shifting modes if you are running the matching electronic drivetrain. Shimano’s EP801 requires the Di2 shifters and derailleur for the coast and auto-shifting. In the case of SRAM Powertrain, while you aren’t required to run an AXS dropper, being that you need all of the buttons on the pod shifters to access all the features of the motor— in addition to T-Type Transmission — you’re sort of ergonomically handcuffed to the wireless Reverb.

This holistic approach creates a bit of an e-MTB ecosystem, which the brands argue allows the rider to extract the best possible riding experience out of their bike. And they aren’t totally wrong, however they’ve created the conditions in which to be able to make that argument.

SRAM’s Powertrain requires a T-Type transmission and to access all of its features. While you aren’t required to use an AXS Reverb, using anything else is going to greater issues with the layout of your cockpit.

Taking the SRAM Powertrain, given that it’s Brose hardware, like the Specialized motor but with SRAM software and logos, there is a pretty good case to be made that the software could also be ported to a TQ or a Bosch or even a (gasp!) Shimano motor.

Theil says there is pressure on SRAM and Shimano to open the firmware up to other manufacturers because those brands are the big fish in the drivetrain market, and smaller players in e-Bike hardware.

“Of course, they are trying to use it as a USP (unique selling point) for their system, but there are other really big players out there. There’s Bosch, who quantity-wise is definitely a really big one, and Specialized is always up there, and we are really pushing on the innovation front,” he says.

“For them (SRAM and Shimano), it’s a narrow line they have to follow. On the one side, they tried to create USPs for their system, and on the other side, they still make their money selling drivetrains. If one of them opens up, then it’s a really nice chance for them to steal quantities for the other one,” Theil says.

While integration and each brand’s e-Bike ecosystem is one thing, consumers are always hungry for standardisation to make their lives easier. Theil doesn’t expect e-MTBs to go the way of Apple and introduce a standardised charging plug — which, to be fair, Apple only did when it was forced to— he does see serious ground to be made up on this front.

“I think as a first step, and a big step is to find standardisation on parts that are wear parts. For example, chainrings. Like why can’t we find a standard interface for e-bike chainrings — for direct mount chainrings — to make it easier?” he says.

There has been a technological arms race when it comes to e-bikes, and we’ve seen a boatload of innovation in a very short time in this segment. With the speed at which we are seeing new innovations in motors, batteries and the ecosystems which support them, it will be interesting to see how things move forward with the drive systems, which bike brands ultimately design the rest of their bikes around.

Photos: TQ, Flow MTB

This feature was made possible with the help of TQ

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