Everything you need to know about choosing the right Bosch electric-drive system (motor, batteries, charger, display) when investing in an electric cargo bike for you or your family

In our experience, electrical engineers aren’t always that great at communicating in ways that most of us understand.

As pioneers of both cargo and electric bikes, we’ve seen too many people get really excited about adopting a bicycle lifestyle only to then get overwhelmed and lose momentum. Why? With all the different products—and different types of a single product—out there, it’s really easy to get confused.

So we spoke to the e-bike experts at Bosch and asked a bunch of questions to help you make sense of your choices. If you’re contemplating an e-bike purchase or assisting a friend with the process, read on. We welcome your comments and questions below!

XTRACYCLE: Why does Bosch offer two different Performance Line e-bike motor upgrade options, the CX Drive Unit and the Speed Drive Unit?

BOSCH: The CX is geared toward mountain- and cargo-bike applications. It’s what you want when you need the most assistance from the motor, traveling up to 20mph. Think of it as setting up your electric cargo bike as a truck or workhorse, with the addition of a feature called eMTB mode [explained below].

The Speed is geared toward commuting, so it doesn’t have quite as much power assist as the CX, but it goes up to 28mph—and will tend to drain battery life faster. Think of it like relaxing the speed governor on an engine in exchange for a lower absolute torque (i.e., turning force) output: it’s faster, but you trade off some power that could help when hauling heavy stuff up steep hills.

Depending on where you live, you might be exchanging access to a higher assist speed for less access to some bike paths. The CX has 75 newton-meters (N m) of torque, and the Speed has 63. The CX is considered a Class 1 e-bike system, whereas the Speed is rated as Class 3, so it’s more limited as far as where it can go, since some places permit only Class 1 e-bikes.

XTRACYCLE: Why would someone prefer the Performance Line CX Drive Unit?

BOSCH: It’s ideal for cargo- and mountain-bike applications, plus it’s got a Class 1 rating with maximum power assist. And in some states and cities, Class 3 e-bikes, with a max speed of 28mph, have further usage restrictions (e.g., New York City).

People for Bikes has a great resource where you can learn about the evolving laws in various places. For instance, California allows all three classes of electric assist, whereas some places allow only Class 1 e-cargo bikes, which top out at 20mph.

XTRACYCLE: Why would someone prefer the Performance Line Speed drive unit?

BOSCH: If you’re a strong and dedicated cyclist accustomed to riding at high speeds, you might not need as much power as the CX offers. Commuters often prefer the Speed drive unit because they ride fast to work anyway, and this decreases their commute time vs. riding a traditional bike or using the CX motor.

XTRACYCLE: Can you tell us a little more about the eMTB (electric mountain bike) mode that the CX drive unit features?

BOSCH: Bosch’s eMTB is a dynamic mode (i.e., electric-assist setting) developed for the rigors of riding mountain trails, but it’s an excellent feature for electric cargo bikes as well. eMTB automatically toggles between the Tour, Sport, and Turbo settings, depending on your speed and the amount of power you’re putting into the drivetrain via the pedals.

On the fly, the eMTB sensors gauge your speed, torque, and cadence to provide the exact amount of electric assistance you need when you need it. We also find eMTB optimizes battery usage and thus maximizes range. It’s kind of a “set it and forget it” mode; the drive will take care of you. Of course, it’s best used in varying conditions where you need to focus on riding, like a trickier city route with hills, gravel shortcuts, and the like.*

ROSS: When we originally launched our Bosch-equipped cargo e-bikes, in 2015, neither CX nor eMTB mode existed. But we asked for Bosch to help us program our bikes for exactly this type of function. Here’s what eMTB mode means in the “real world” of cargo bikes: 1. You’ll get the maximum amount of torque and assistance available from the system when you are getting started from a stop. We have found this to be crucial for safely crossing intersections as well as speed-generated gyroscopic stability when first getting started with an awkward or wobbly load. 2. The motor won’t assist as much when you aren’t pushing hard. In other words, it’s smart about how much assistance you need based upon the power input from your legs. This helps conserve your battery capacity and also helps with speed control when navigating in crowded conditions. 3. Sometimes hills sneak up on us, and we forget to switch to turbo mode in time. eMTB mode means that you’re ready for anything without having to think about it. 🙂

XTRACYCLE: Can you explain the difference between having more torque with the CX motor vs. a higher top speed with the Speed motor?

BOSCH: You could say that having more torque with the CX is like having more strength to carry and climb. The Speed, as its name suggests, is better for going all out under less extreme riding conditions, when you’re not so worried about climbing steep hills or hauling heavier cargo.

XTRACYCLE: Can you tell us more about the Walk Assist mode that your Performance drive units offer? And is it different on the CX and Speed motors?

BOSCH: Walk Assist is particularly helpful with heavily loaded cargo bikes. If for some reason you need or want to push your loaded cargo bike up a hill, Walk Assist will help you get to the top more easily by slowly, automatically driving the pedals forward while you walk alongside, guiding the bike with your hands on the handlebars. Simply press the Walk Assist button; it’s at the bottom of the Purion display. Then, to activate, press and hold the “+” bottom while you walk. Both CX and Speed motors feature Walk Assist mode.

XTRACYCLE: Why might someone want to have two 500 watt-hour batteries for a total of 1,000 watt-hours on an electric cargo bike?

BOSCH: “Range anxiety” is real. If you want to maximize your range and not have to recharge batteries as often, go for two batteries and a total of 1,000 watt-hours. It’s a great feeling knowing that you have sufficient battery capacity to ride fully assisted for miles and miles and miles.

XTRACYCLE: Does Bosch have anything to help people determine that range and what best suits their needs, if they’re trying to decide between getting a 500 or 1,000 watt-hour electric-assist system?

BOSCH: Yes, if you go to the Bosch website’s Range Assistant, it can help answer all those questions. Just enter your riding weight, terrain type, wind, hills, and so on and the Range Assistant will help you calculate your range. 

ROSS: The Range Assistant is a really cool tool, but we have found it can sometimes be inconsistent with our own experience riding electric cargo bikes on a daily basis. That said, the RA is great for helping you better understand all of the variables that can impact your range: level of assistance chosen, combined rider and cargo weight (the RA has a max. input of 331 lbs for calculating range), type of drive unit, number of batteries, stop/start frequency, road conditions, hilliness, etc. Also, bicycling lifestylists tend to ride year-round in all kinds of weather conditions, so temperature variations can be a significant variable when it comes to calculating battery charge and life. But this kind of all-season riding isn’t the norm, so it’s no surprise that Bosch has excluded temperature from the Range Assistant tool. That said, Bosch does recommend always charging and storing batteries indoors, rather than, say, leaving a battery connected to a bike stored in a cold garage throughout the winter.

XTRACYCLE: Do you see electric cargo bicycles beginning to fundamentally change transportation in the U.S., Europe, and beyond as we progress further into the 21st century and employ more sustainable solutions for moving people and their stuff?

BOSCH: Yes! We see the cargo bike as a great tool for humanity, and it’s even better with electric assist. An electric cargo bike gives people a lot more access to a lot more things without having to drive a car or walk to public transportation. Cargo e-bikes also provide health and fitness and a great experience. We’ve seen more and more cargo e-bikes replacing cars over the years, and it’s not slowing down. There are huge benefits not only for people but for the environment and people-oriented cities as well.

ROSS: There are many, many manufacturers of e-bike components worldwide. Here at Xtracycle, we have over 20 years of experience with different, unreliable electric-drive systems, plagued by poor diagnostics, impossible repair, and unobtainable replacement parts. So we were delighted when Bosch, an automotive- and electrical-parts giant, entered the e-bike world. Early on, Bosch proved itself in the European market as the go-to system for e-bikes. We lobbied hard and were fortunate to be chosen as the first U.S. customer for Bosch eBike Systems USA. Bosch continues to set the standard for parts, service, reliability, and product quality—and still manages to play a key role in leading the legal-advocacy movement for electric bikes. We like them and think you will, too.

Thanks to Brian Sarmiento, Brian Cleveland, Jonathan Weinert, and the rest of the Bosch USA crew for all their help!