ST5 motor stopped working, E 210101 code, works after some time


New Member
I had a strange failure on my ST5. This is same bike that had charging problems (along few others). Any words of wisdom on below are appreciated.

I had bike repaired by New Wheel in SF due to charging problem and torque sensor issues (plus few other minor things). It worked well for few weeks then I went on a monthlong trip and left bike plugged in - so battery was full. Few days ago I took it on 15 mile commute to work only to discover that Shimano shifter battery was dead (my bad). No worries - I'll paddle it in middle gear at 15mph - I'll get there and back. Then after some time - about 8 miles into my commute - I noticed it was really hard to paddle and realized that my motor was just not helping. I cycled through assist levels, turned system on/off, calibrated sensor, and even removed battery. No luck. After some time - I started getting E210101 error code.

I reached work and left bike on as I often do. Usually it shuts down on its own after a bit - but this time it actually drained battery completely when I noticed it at the end of the day. Charging was intermittent - I could charge for some time then had to remove battery and charge internally. It is possible I had to power off charger before plugging it in - I read about it - but it worked fine before without need to do that.

Any suggestions on troubleshooting? How does one "reboot" the bike short of draining battery. How long must one remove battery before true reset happens?

Paddling 70 lb bike w/o motor assist was not fun... I am nervous about finding myself in similar situation again...


  • 7E722CED-2222-474B-AA40-A1E276F861D8.jpeg
    334.7 KB · Views: 115
  • D1F7543D-359B-4C41-831B-9BACD5F4D80C.jpeg
    363.6 KB · Views: 116
  • 9BFBE009-8530-4757-A158-EDD813AC2A7F.jpeg
    327.2 KB · Views: 132
That’s pretty strange. I also have an ST5 from The New Wheel and have had the sensor problem (that Stromer themselves caused with a bad firmware update) and once, when I removed the battery, the OMNI unit died when I put the battery back in. The OMNI had to be replaced, of course. In fact, with the 4G update, I’m now on my third OMNI on an 18-month old bike.

My suggestion, before taking your bike in, is:

1) do a visual inspection around the motor and torque sensor for any disconnected or loose wires
2) turn off the bike, remove the battery, then put the battery back in and restart the bike
3) recalibrate the torque sensor via menus in your OMNI

If none of that works, then The New Wheel’s service department is your best bet. They really know this bike well and will get it fixed. There’s not much self repair you can/should do on this bike when it comes to the electronics.

Despite the quirky, somewhat unreliable nature of this bike, I love riding it. It’s fast, sporty and pure enjoyment. Every time I’ve had to take it in for service or repairs and had to ride my back-up (R&M Superdelite GT Rohloff), I’m reminded how awesome the ST5 really is.