Choosing an eBike System

eBike Systems Overview

There’s no doubt the Australian eBike market is growing rapidly. Not even 18 months ago, we didn’t have all that many quality hub drive options, let alone any mid-drive systems to choose from. With the adoption of EN15194, we’ve now had a flood of high quality Pedelecs (electric assisted bicycles) hit our shores.

There are close to a dozen eBike drive systems to choose from, with 7 of them mid-drives that have arrived in the last 12 months. These are the likes of the Bosch Classic+, Bosch Gen2 Active Line, Bosch Gen2 Performance Line, Bosch Gen2 Performance CX Line, Impulse 2.0, Bafang and Shimano STEPS. Then you have dozens of eBike models from different manufacturers equipped with these different drive systems. If you’re new to the world of eBikes it can be a little overwhelming trying to understand the differences between each system.

So we decided to create a drive system overview of all the eBike systems we’ve tested so far including Pedelecs conforming to EN15194 (250 watt eBikes without throttle), and eBikes still using 200watts (with throttle). The overview summarises the drive system and its operation along with any electronics that are standard with a specific system. The idea is that this can be used as a reference for buyers looking at their first eBike, and for us to reference in reviews and previews so we’re not always repeating ourselves from testing the same drive system on a different eBike.

You won’t find any performance comparisons here, since each eBike is different in weight, components, and has different handling characteristics. For example, an eBike with a drive system capable of 80Nm of torque may have the best climbing ability with the right components and weight on paper, but the same kit may be fitted on a trike, which may not exhibit the best climbing ability. Therefore it would be unfair to say a single drive system is the outright best performer, as this depends heavily on what eBike it’s equipped to.

Instead, comparisons will continue to be more related to reviews, where eBikes are given a score which is comparable to other eBikes in the same category.

This is a live document, so as we continue to test more eBike systems and learn more about them, we’ll continue to update these pages.

You can check out an overview of the eBike systems we’ve tested so far:

  • Shimano STEPS
  • COMING SOON Impulse 2.0
  • Bosch Classic+
  • COMING SOON Bosch Gen2 Active Line
  • Bosch Gen2 Performance Line
  • COMING SOON Bosch Gen2 Performance CX Line
  • COMING SOON Bafang BBS02 750w
  • COMING SOON Bafang BBS02 500w
  • COMING SOON Bafang Max Drive
  • COMING SOON Geared Hub motors
  • COMING SOON Direct Drive motors

Batteries

The most common cell used in OEM eBikes are 18650 cells which have a nominal voltage of 3.6v and a max voltage of 4.2v. These cells are produced by manufacturers such as Samsung, Panasonic, and Sony to name a few. Not all cells performance are equal, even if they have the same capacity. Some distributors will simply say their battery packs are Samsung Cells, which can catch a first timer’s attention. However sometimes these cells are low grade and have poor discharge and voltage sag. So it’s always best to ask what cells come in your battery pack if it’s from a small distributor. You’ll tend to find most reputable manufacturers won’t mention where their cells are from or they will simply say “Made in Japan”, however many DIY enthusiasts are pulling packs apart on forums and posting their findings.

Battery capacities are determined by multiplying voltage and amp hours to give you watt hours. Most OEM eBikes in Australia come with 36v batteries. This means that there are 10 cells in series (10S) which gives 3.6v nominal x 10 cells equals 36v. You can then calculate the capacity in watt hours by first determining how many cells are in parallel, and the amp hour capacity of each cell.

Shimano STEPS 36v 11.6Ah (10S4P) battery • <a style="font-size:0.8em;" href="https://www.flickr.com/photos/ebikereviews/19751206363/" target="_blank">View on Flickr</a> Shimano STEPS 36v 11.6Ah battery

For example, Bosch uses Samsung 29E cells or LG 11865 cells and we know Samsung 29E cells have a capacity of 2900mah per cell. Bosch’s Powerpack 400 is 11.6Ah and in fact 418Wh. We know it has 4 cells in Parallel (4P) since 2.9ah multiplied by 4 equals 11.6Ah. We know the nominal voltage of the pack is 36v, so 36v multiplied by 11.6Ah equals 418watt hours. Therefore the technical configuration of the battery pack is 10S4P, and you’ll often see those in the DIY community referring to their own packs using the same numbering system.

Custom battery for offroad use only: 21S9P, Samsung 25R cells (75.6V, 22.5Ah, 1701Wh) • <a style="font-size:0.8em;" href="https://www.flickr.com/photos/ebikereviews/15824966639/" target="_blank">View on Flickr</a> Custom battery for offroad use only: 21S9P, Samsung 25R cells (75.6V, 22.5Ah, 1701Wh)

Efficiency is discussed in watt hours per km or wh/km. Although no OEM bike manufacturers currently display this output on their LCD’s, you can often find your efficiency by calculating the capacity of your battery pack divided by how many km you’ve traveled.

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Pedal Assist System (PAS)

In order for an eBikes controller to know when and how much assistance to give you, eBikes come fitted with sensors. Some of these sensors measure how fast the pedals are rotating (cadence sensors), and some measure how much force is being applied to the pedals (torque sensors). Others use a combination of both, and include the speed of travel to determine when and how much assistance to give you. Assistance isn’t just about starting from a standstill or climbing, but also how natural the system feels to human input as you pedal.

Torque sensors

Torque sensors measure how much force is being applied through the pedals. Based on a reading the torque sensor feeds the controller, the controller can then calculate how much assistance to give you based on how much force it’s reading. The ‘harder’ you pedal, the more assistance you will get based on a torque multiplier. For example, in a hill climb, you will be pushing down harder on the pedals then you would if you were pedalling on a flat surface, so the torque sensor tells the controller you need even more power. This also depends on what assistance level you have set. Some eBikes come with 3 levels of power, while others come with up to 7.

There are also a variety of torque sensors available from different manufacturers. Some torque sensors simply measure torque by detecting flex in the dropouts, other torque sensors are built into the drive unit (common among mid-drives) or bottom bracket (common among hub motors) and measure torque from the force directly applied to the pedals, and others go as far as hiding it in a rear hub!

Torque sensor located in the dropouts • <a style="font-size:0.8em;" href="https://www.flickr.com/photos/ebikereviews/9457876878/" target="_blank">View on Flickr</a> Torque sensor located in the dropouts above the axle nut cover
Bionx torque sensor strain gauge in hub • <a style="font-size:0.8em;" href="https://www.flickr.com/photos/ebikereviews/9668315197/" target="_blank">View on Flickr</a> Bionx install their torque sensor strain gauge in their hub

Some then take it a step further and bundle torque sensors with cadence and speed sensors, calculating thousands of readings per second to know how much assistance to give you and when, based not just on force, but how fast you’re travelling, and how many revolutions per minute the cranks are doing.

Bosch Gen2 Active Line processes 1000 readings per second • <a style="font-size:0.8em;" href="https://www.flickr.com/photos/ebikereviews/14425859644/" target="_blank">View on Flickr</a> Bosch Gen2 Active Line processes 1000 readings per second from Cadence, Torque, and Speed Sensors

Some torque sensors may feel like you need to put in a lot more effort to get more power, even on the highest assist setting, while other systems may take awhile to react to small changes in pedal force or cadence. Both these points affect how fluid the system feels to a rider as they pedal. The less abrupt the changes in assistance feels based on how you’re pedalling, the more natural the ride will feel.

Every torque sensor-ed eBike system we’ve tested to date has felt different!

Cadence sensors

COMING SOON

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Geared motors

COMING SOON

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Direct Drive motors

COMING SOON

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Mid-drive Systems

Mid drive systems are located where the bottom bracket would usually be and allow you to make use of bicycle gears allowing the motor to run at its optimum RPM. This also means that assistance is directly applied through the bottom bracket axle/chainring. The torque from mid-drives acts directly on the bracket shaft, and there’s no drive sprocket as such. This means you’re getting power directly through each one of your pedal strokes when riding. Mid-drives generally run more efficient (get more range from a battery) than hub drives, because you’re able to select an appropriate gear depending on the terrain you’re tackling while being in the optimal RPM range. The negative to this is if you’re in the completely wrong gear, it’s likely the mid-drive your riding will feel like it’s not delivering any power, since it’s not operating at an optimum RPM. Mid-drives therefore require you to always be in the correct gear (or at least close to), so you get the most available power from the motor, and this is critically important with all mid-drives on the market.

Inverted Bosch Classic+ Drive Unit • <a style="font-size:0.8em;" href="https://www.flickr.com/photos/ebikereviews/13424422874/" target="_blank">View on Flickr</a> Inverted Bosch Classic+ Drive Unit
Impulse 2.0 Drive Unit • <a style="font-size:0.8em;" href="https://www.flickr.com/photos/ebikereviews/16217912518/" target="_blank">View on Flickr</a> Impulse 2.0 Drive Unit

One thought on “Choosing an eBike System

  1. My wife and I have been looking into different systems for biking, and we wanted to learn more about EBikes! I love that they actually have systems in place to assist you with pedaling and sensors to see how fast you are doing so. It would be interesting to see how fast we are able to go in the end.

    June 16, 2017 at 12:54 am

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