Hi, fellow eBikers//
Haven’t followed this forum for a bit - I guess the pandemic is cramping my style. Wanted to chat about the apparent speed differences between he Bosch cycling computers and other measuring devices.
I have an R&M Delite with the big Bosch motor, the Enviolo 380 Constant Variable Speed Hub, and the Gates belt drive. It came with two batteries and the Kiox display, which I did not care for - one bit. After spending some time on this forum, and paying attention to Alaskan, bought an 8 Gig Nyon from a company in Germany. Had my LBS swap out the Kiox for an Intuvia and had them install the Nyon controller. Stuck the Nyon on the Intuvia head and away I went. Absolutely love this machine. The Nyon is the best cycling computer I’ve ever owned. I used Garmin Edges for about fifteen years. Currently have a 1030, which is pretty good, but not in the same league as the Nyon.
One thing that Garmin does is allow the Edge to calculate the tire’s circumference and use it in its calculations. It’s fairly simple and uses the concept of ‘an infinite number of inaccurate measurements results in an exact measurement.’ That might sound like a geek-ism, but it’s true. That’s how Kalman Filters work and that’s how your cell phone is able to provide such an accurate position. I believe this is how it works in a cycling computer. Full disclosure - Garmin does not publicize this and it’s my take on how it could work.
First, the cycling computer has to have a GPS engine. And - you have to have a way of sensing the tire’s revolutions. The magnetic sensor will do it. Garmin now uses an accelerometer, which seems to work fairly well. Fire up the computer and the GPS gets your position. Time To First Fix (TTFF) on these newer engines is quite quick. The computer starts its routine when it senses the end or a revolution, which is the start of the next revolution. It also records the start position, and records positions at some interval throughout this process. You pick the interval - fifteen seconds? At the end of the routine you have the number of revolutions and can easily calculate the distance traveled. Calculating the circumference is grammar school math. How many revolutions? I’d start with 200. A two foot diameter wheel has a circumference of 6-1/4 feet or so. 200 revolutions is about a quarter mile.
The eBike has so much power available that you could run this routine every fifteen minutes or so and get a very large number of circumference measurements and not seriously impact the battery. This will yield a very precise measurement. Think about a bell-shaped curve with a very pointy apex. If you don’t believe me find someone who understands statistics and ask her.
For those of you who understand computer programming you’ll realize that this a very simple algorithm. And writing the code wold be a piece of cake.
The easy thing for Bosch to do is write the code and test it. Optimize it. Run it by the OEMs to ensure that they’re OK with it. Put it on the Nyons and allow the user a choice - input the circumference or allow the Nyon to calculate it. By the way - that’s what Garmin does…
And - oh, the new Nyon. It’s supposed to be available in North America by the end of the year. It appears to have a smaller display than the older one. It does include a touch screen that allows you to move from screen to screen with your finger tips. Maybe I’m a Neanderthal, but I really don’t like the idea of having to essentially change displays to get different information. I need to pay attention to the road. I’ve put together a custom screen on my old Nyon that has everything I need on it. I know exactly where to find any information I want. Just glance down and I have it. I like that. Have not seen the specs for the new Nyon, but will purchase another old Nyon as a backup in case the first one dies. Guess Bosch is trying to purge its inventory so the old Nyon is going for €273, which is a good price.
Finally - need to reiterate that the Nyon is the best I've ever used. Has everything I need - WiFi, Bluetooth, HRM, beautiful display, great navigation interface, and the ability to customize just about everything.
Anyway,
Happy eBiking…
Bob