Overview of Bosch Electric Assist

I just finished the Certification process for Bosch e-assist maintenance and repair.  While it’s still fresh in my head I thought I would share with you some of the details of the Bosch system.

One of the big problems with the e-bike industry is that players come and go.  It’s hard to know who will still be around to honor warranties or offer replacement batteries.  Bosch is a global company employing over 400,000 people.  They were the first company to use lithium-ion batteries in a power tool.  They make automotive parts, power tools, on-demand water heaters, home appliances-their products are everywhere.  The first version of the Bosch e-motor was a repurposed power steering motor from a Mercedes-Benz automobile.  The chairman of the board, Dr. Volkmar Denner, is an avid cyclist who was responsible for the e-bike division being created in the first place.  In Europe, half of all bicycles sold have e-assist and Bosch is the leading brand.  All that points to them being in the e-bike market for the long haul.

Bosch divides their e-bike system into three subdivisions; on-board computer, batteries and drive units.  There are three on-board computers; Purion, Intuvia and Kiox.  Purion looks about the size of a regular cycle computer but has the motor control buttons built in, Intuvia has more screen room for all the riding data. The motor control buttons are separate so the computer can be placed on the stem and the motor switch near your thumb for better control.  The Kiox has a color screen and can be paired with some low energy Bluetooth accessories like heart rate monitors.

There are three versions of batteries available.  The Powerpacks come 400 w/hr or 500 w/hr in either rack or frame held versions.  The Powertube is a 500 w/hr battery which is designed to integrate into the bike frame for a more unified look.  The DualBattery configuration allows for two batteries to be connected for longer range.

The Drive Units come in four models; the Active Line, Active Line Plus, Performance Line cruise/speed and the Performance Line CX.  It’s best to talk about e-assists in terms of torque, that is a measure of how hard it can push you down the road.  The Active Line is the smallest, lightest and quietest motor in the line-up.  With 40 Nm of torque, 250% maximum assist and an average range of 35 to 45 miles, this is the perfect around town e-bike system.  This is similar to the Shimano STEPS e5000 unit you may see on some HP Velotechnik trikes.  The Active Line Plus has 50 Nm of torque and 270% maximum assist with the same range.  This is the motor you will see on the Terratrike EVO tadpole trike.  Other recumbent companies such as Ice and HP Velotechnik will offer the Shimano STEPS e6000 as an alternative.  The Performance Line comes in two versions; the cruise and the speed.  Both have 63 Nm of torque; the cruise has an assist limit of twenty mph and the speed twenty-eight mph.  You will see the Performance Line used in power hungry applications like mountain biking and cargo bikes.  The similar 70 Nm Shimano STEPS e8000 will be offered on Ice, Azub and HP Velotechnik recumbent trikes.  The Performance Line CX is the strongest of the Bosch units at 75 Nm of torque and 300% maximum assist.  This is what you will see on mountain bikes made for serious climbing.  The CX Line has an optional eMTB mode which provides power from 120% to 300% based on pedal pressure instead of having to switch assist levels with your thumb.

All the Bosch units have five riding modes; off, eco, tour, sport or eMTB and Turbo.  The off mode allows the cycling computer functions to display without powering the motor for times on the ride when you don’t need assist.  Eco supplies 40% to 50% assist (depending on motor) to provide a slight amount of help and allow the maximum amount of distance per charge.  This is the mode most companies base their distance figures on.  The distance numbers I quoted earlier from Bosch are based on the average mileage during real riding using all the assist levels.  Tour mode supplies 100% to 120% assist. That means the motor is suppling the same amount of power as the rider.  I think this is the mode most folks will use to keep up with the group.  Sport mode is 170% to 190% of assist.  This is the “motor up the big hill” setting.  It’s best not to stay in it too long to save battery power for the rest of the ride.  The Performance CX motor can replace this setting with eMTB.  The difference is that the assist range is wider (120%-300%) and allows more finesse when climbing using an e-mountain bike.  All that power might cause the tire to lose traction without the increased rider input based on pedal pressure.  The last mode is Turbo which provides the maximum amount of assist (250%-300%).  This is the “here comes the big, angry dog” mode.  Great for a sprint or to climb the last steep pitch but nothing you want to maintain very long because it will eat up the charge in the battery.

Something to know about e-assists is that they all have proprietary software that bike shops need to have to be able to work on your trike.  Part of the training I received was how to use the software and special hardware needed to connect our computer to the assist.  One of the considerations when buying an assist is where you need to take it to be serviced.  The good news for Bosch and Shimano e-assists is that many regular bike shops have access to the training, software and tools they need to work on your new e-trike.  Trek dealers sell e-bikes that use Bosch e-motors; shops that sell bikes equipped with Shimano Di2 electric shifting have everything they need to work on Shimano STEPS e-motors. That’s why we have chosen to sell recumbent trikes equipped with them over other brands.

I came away from the training excited about Bosch e-assist systems and about the company in general.  They are going the extra mile doing the training they provide and are setting the standard of what other brands should offer.  Like everything, there are trade offs with the style of assist Bosch offers.  It is not something you can add to a bike or trike you already own.  The frame of the bike or trike must be made specifically with the Bosch motor in mind.  The upside is that the motor looks like part of the trike and is fully integrated into the design.  The hub motor style kits look like an afterthought with wires routed with electrical tape, zip ties and Velcro straps running the length of your trike.  The direction the industry is headed is toward integrated systems like Bosch and Shimano.  The major recumbent companies like Terratrike, Ice, HP Velotechnik and AZUB are offering systems with either Bosch or Shimano mid-drive motors.  For more information about Bosch or other e-motor related subjects contact Lee@bicycleman.com.

January 25, 2019 |