Other Rail 5 - mullet setup and 504 error?

[Drewf]

OK, I did search the forum and was surprised to not find any results on "mullet" and "504 error".

I have a 2020 Rail 5 and threw a 27.5 rear wheel on a couple weeks ago. No issues other than speedo being off since I dont have the Kiox (mine is Bosch Purion) to change wheel diamter. Rode it many times with the mullet setup with no issues, but today suddenly getting the 504 Error. Bike still lets me ride without issue so far no limp mode, but not sure if the 504 error is somehow related to the smaller rear wheel? I have not have any firmware updates done yet, so I am sure my firmware is out of date. Just odd that I never had any issues until the 27.5 rear wheel.

Thanks for any input here.

 

[Paulquattro]

Hi
I would not have thought it was related as the bike / Motor doesnt know what size the back wheel is .

 

[Jujujuice]

Hi there I had the same error on my previous rail and it was just a firmware update! It could be the timing is coincidental.

 

[Juise]

Test if the wheel magnet sensor in the rear triangle reacts to magnet. If not, the sensor is gone.
The replacement is a bit pain in the butt as you need to cut the rear brake line and possi ly drop the motor to get the sensor routed.
This is warrantied by trek and i suggest you get them to do it.

 

[Paulquattro]

With reference to the magnet
Just make sure its bolted on correctly ive seen them the wrong way round before with the curve not in line with the bolt circle if you get my meaning .

 

[Drewf]

Hi All and thanks for the replies. After doing some research is seems the the Bosch engineers have some sort of anti-hacking measure in place to keep folks from messing with the wheel sensor to make the bike go faster. (could be other reasons they do this, but this seems to be one reason) I looked up the code in the Bosch manual and it relates to a wheel sensor issue. I double checked the sensor was mounted tight and aligned correctly and not caked with mud or anything.

Just for reference of anyone else that has this issue, while the error was present the pedal assist was severely impacted. The pedal assist usually cuts out at 19.9mph but with the error it would cut out at 13mph. It would also randomly cut pedal assist at random times. It was very annoying, but did reset on its own after riding it with the wheel size the computer expected.

I ended up putting my 29 wheel back on the rear and had to ride it for about 1.5 hours and then the computer error finally reset and everything is back to normal. Long story short, if you use a 27.5 rear wheel you need to change the wheel diameter in the computer or it thorws the wheel sensor for a loop.

 

[Juise]

Hi All and thanks for the replies. After doing some research is seems the the Bosch engineers have some sort of anti-hacking measure in place to keep folks from messing with the wheel sensor to make the bike go faster. (could be other reasons they do this, but this seems to be one reason) I looked up the code in the Bosch manual and it relates to a wheel sensor issue. I double checked the sensor was mounted tight and aligned correctly and not caked with mud or anything.

Just for reference of anyone else that has this issue, while the error was present the pedal assist was severely impacted. The pedal assist usually cuts out at 19.9mph but with the error it would cut out at 13mph. It would also randomly cut pedal assist at random times. It was very annoying, but did reset on its own after riding it with the wheel size the computer expected.

I ended up putting my 29 wheel back on the rear and had to ride it for about 1.5 hours and then the computer error finally reset and everything is back to normal. Long story short, if you use a 27.5 rear wheel you need to change the wheel diameter in the computer or it thorws the wheel sensor for a loop.

This cannot be. When you put smaller diameter wheel, the wheel turns faster and the sensor turns faster - > assist cuts earlier than actual land speed of 25.

The sensor reads only the frequency of the magnet passing the sensor (how many times per second) and calculates with the preset wheel circumference when the 25km/h is reached.

Id say the magnet was wrong way around so the signal was weak and gave an error or some thing similar.

I have a mullet setup for bikepark and such and i went to the bosch dealer so they set the correct smaller diameter to the.motor so i could still reach almost 25 actual km/h with the 27,5" tire.
Now when i ride trails with my 29" rear wheel it goes little bit faster than factory setup, since the rear wheel circumference has been told to the motor to be the ~2100mm of the 27,5" tire (instead of the stock about 2300mm)