Differences between Derby Cycles Impulse2.0 and Impulse2.2 (EN)

The durable Impulse1.0 motor that was developed in coorperation with Daum Inc. in 2011 was developed further and installed as Impulse2.0 in several bikes model year 2014, 2015 and 2016.

After a few motor failures in the first half-year of 2015 and the statement of Derby Cycles field staff that these ocuurences are one time failures only (1st failed motor: 75 mi) followed a large number of motor failures in the second half-year (2nd failed motor: 1,976 mi). Somewhere in between there was the peak level, where the owners had to wait several weeks for their bikes because the motors were fixed and installed again.

Based on my own experiences with the Focus Crater Lake Impulse2 (german only- sorry) and a complex internet forum research I created a google table with all occured failures and the possibility that affected people can add theirselves with their information about bike and failure.

In this time Derby Cycle improved the service quality. The failed motor and the new one were send at the same time, so the customers could get their bikes back very soon (4th failed motor: 3,221 mi).

In summer 2016 the idea for the pedelecmonitor came up and I summarized the data. The mileage of the failed units was really low.


Meanwhile Derby Cycle has a really good service. A motor change can be performed in 2 or 3 days. The special thing about the new Impulse motors is that you have an additional two years warranty on the motor.

Due to the large number of failed units, Derby and Daum made construnctional changes and software modifications. The first step was to change the inner parts of the failed units like crankshaft and gears. But the motors failed even earlier (5th failed motor: 530 mi).

The completely new build motors are now called Impulse2.2. I think the production line started arround November 2016 from motor-ID 600,000+. I contacted some biker in the german Pedelecforum and they share their mileages and experiences now frequently.

From the two sources, here and here, I got the information about changes of Impulse2.2.

Changes in the production line:

  • fine balancing of the rotor
  • after completing the production line the motor go on a bench for noise measurement
  • the application of Lubricants is now performed by robots
  • the lubrication is performed by graphit oil

Constructional changes:

  • the big metal gear is fine grounded
  • the big white plastic gear got larger bearings
  • some constructional changes at the freewheel
  • the pawls are vibritory grinded
  • constructional changes at the bottom bracket sealing and the cable bushing
  • there is a small sticker on the housing, behind that is a Gore-Tex membran
  • the crank shaft has a anti rust alloy

Service improvements :

  • New Software for the Impulse II motor and the diagnostic tool from April 2017 available
  • With the new software the motor could be calibrated and checked for a failed force sensor

Root causes for the design changes

You can read in different forums about motor problems of Kalkhoff-, Focus- and Univega-bike owners.  In most cases the failures are

  • croaking / squeaking noise, later also vibrations in the crankshaft
  • clicking or clacking noise from the pawls
  • wheel spin at crank shaft due to cracked free wheel
  • support interruptions


The member ebicker1 (#117) provided me photos of his Univega. Many many thanks. His new Impulse2.2 motor is running without failures since approx. 1,400 mi.

The current runtimes of all failed and intact Impulse motors you can find here, they will be updated every month!