Hello,
I am trying to get your bridge to work with my Kettler ergometer FX1 (I am hoping that since you say it works with EX1, it will also work with my FX1). I bought an R Pi Zero WH.
Great of you to have made this bridge, by the way ! 
I have a question. I have gone through steps including the npm install, which I believe succeeded (lots of messages).
BUT - how do I connect the Kettler AND the keyboard at the same time? It has only one USB port.
Now, without bike connected and the keyboard connected, when I run “sudo node server.js” I get:
“[KettlerUSB] port is not open, retry in 10s” looping until I Ctrl-break
I assume that is because the bike is not connected?
But if I connect the bike, how do I type in “sudo node server.js” since I wil not have the bkeyboard connected (due to lack of a second USB)?
2 - I also tried to go through the steps “automatic launch with the raspberry”
BUT when I try to create the symlink “sudo systemctl link /home/pi/kettlerUSB2BLE/kettler.service”
It does not find the file, and in fact ot is true - that folder does NOT contain a file kettler.service.
Thanks for any help and explanation!