Modifying the Bionx Default Settings

Via E-mail:

I bike currently on a Trek 700 Navigator 2011 with BionX G2 controller. This bike has an adjusted speed of 25 km/h in Europe. I would like to increase the speed to 35-40 km/h. What opportunities do I have with my current set or what is needed to achieve this adaptation.

With BionX G1 and G2 controllers, there are five programming modes/codes for the user. These modes allow you to adapt the system to your bike, your preferences, and the regional units of measurement (miles or kilometers).

All other BionX codes are intended for authorized BionX dealers. This includes modes that can turn off the maximum throttle speed and the maximum assist speed. When this mode is on (which it is by default) the maximum speed is 33 km/h or 20.5 mph.

The user accessible programming modes are:

  • Select km/h or mph: Set your speedometer and odometer to km/h or mph.
  • Regeneration/Brake output: Fine tune how your brake lever actuates your regeneration mode.
  • Clock adjust: Set the clock to your local time.
  • Tire circumference: Set the accuracy of your speedometer and odometer by inputting the correct tire circumference. (I’ve heard of people who intentionally have put in an inaccurate tire circumference in order to circumvent the speed limit. This only fools the system into thinking the bike is going slower than it actually is, but it does not eliminate the default upper limit of the Max Speed setting. This is not recommended, because with an inaccurate tire circumference setting, your speedometer and odometer readings will be inaccurate.)
  • Flip Display: On G2 units, you may choose whether the power level is displayed on the left or the right.

These programming modes are on Page 20 of the BionX User Manual.

Via E-mail:

The “BionX CANBus 350W HT SL G2 Motor for 20″, 24″, 26″, 700c wheels” in your parts list does not have an option to choose the wheel size. The speed limit is coded into the hub according to the wheel size.
I used to ask this question and you told me that you will check with BionX. I also told you that I bought the BionX 20″wheel from an online shop and it was coded wrongly for the 700C. Therefore the top speed is reduced from 32 kmh to 22 kmh.

You must be referring to the inaccurate information found on regarding this motor.

There is only one BionX CANBus 350W HT SL G2 Motor for all wheel sizes.


The motor must be programmed for size of the wheel on which you have installed the motor (18″, 20″, 24″, 26″, 27″, 700 c, or 28″).

After you have received the motor, reprogramming the motor can only be done by a BionX dealer with BBI software (BionX Bike Interface).

It is possible for a dealer to order the motor from BionX pre-programmed for a particular wheel size, but this is unusual since BionX mostly sells motors directly to dealers who have the BBI software.

Once the motor is programmed, the wheel circumference can be fine tuned within a particular range. (See above for the relevant manual page.)

For example: A 700 c wheel comes pre-programmed for a tire circumference of 2199 mm. You can adjust that to anywhere from 2111 mm to 2331 mm. But you cannot adjust it down to, say, 1463 mm (the average circumference of a tire on a 20-inch wheel) without reprogramming the motor using BBI.

When BionX motors are purchased as part of a complete kit where the motor comes already in a wheel the controller is pre-calibrated for an approximate corresponding tire circumference.

These are the default circumferences that come with pre-programmed BionX motors:

18-inch wheel = approximately 1436 mm circumference
20-inch wheel = approximately 1596 mm circumference
24-inch wheel = approximately 1915 mm circumference
26-inch wheel = approximately 2075 mm circumference
27-inch wheel = approximately 2156 mm circumference
700 c wheel = approximately 2199 mm circumference
28-inch wheel = approximately 2234 mm circumference

But because a fat tire will have a greater circumference than a thin tire, the most accurate way to calibrate your BionX controller is to measure the circumference of your wheel yourself by rolling the wheel one exact rotation, and measuring that linear distance with a tape measure. The controller will accept a range of circumferences based on the wheel.

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