BNB

I'm not sure if this is the correct section to post this issue - I'm sure you'll let me know.

I have a new e-bike tandem with Bosch system. We had a fabulous 300 miles (12 rides) on it before the assist erratically started cutting out on us. I'm hoping there might be Bosch e-bike knowledgeable people here.

We were rather surprised on our last ride and didn't understand what was going on. Today the issue was worse and I could see on the smartphone hub that the speed was jumping around from our true speed of about 13mph in Eco mode on flat terrain up to 30mph with readings all over the place when it cut out but always above 20mph (which I believe is the limit for this system, though not sure).

I've attached pics of the battery, motor and magnet/sensor location. Any help is appreciated. Our local Bosch service shop must be the worst shop in the country -- the owner makes it a sport to fire his mechanics so turnover is high and skill level is low.

well biked

We have sold quite a few ebikes in my shop that use Bosch drive systems. In the rare cases where there have been problems of any kind with anything Bosch-related, Bosch warranty has been great. Since you say it's a new bike, go through the proper channels, even if it means contacting Bosch directly, to get the problem covered under warranty.

Bmach

+1 👆

HillRider

Agree that Bosh is the place to start with this problem. However, I did notice your picture shows the wheel magnet and the pickup sensor farther apart than I'm used to with my cyclometers. Try adjusting the gap between them smaller and see if that helps.

BNB

Will try Bosch (have to find contact info). How best to get magnet and sensor closer? It the magnet in the correct position along the spoke?

thanks for suggestions.

LeeG

Can’t tell looking at the photo but the correct position is what works for the sensor and magnet not the spoke or chainstay. How well do they align when at closest position? On the photo it looks like the magnet is below the sensor, it should align with the round section on the sensor.

fooferdoggie 

the sensor needs like this https://www.google.com/search?q=bosc...80YjA0dCBS-TKM
but there is a line on the sensor and the magnet needs centered on that. the line can be closer to the bulb end. you see the line right after the logo on the inside? thats where the magnet need centered. the magnet does not need to be really close though.

BNB

I will realign and test as soon as temps drop below 90F here! I suspect it's the sensor at this point.

fooferdoggie 

yep it is. seems there are two sensors one with the it close the back and the more front one. .I ended up paying to shop to adjust mine as I bought it was the bulb on back. as long as the magnet is in the right position I ahve had it spin almost 90 degrees around the spoke and it still worked. bosch can be finicky about the alignment. now I know why trek pot the magnet on the disc brake so it never has to be adjusted

richosti

I'd suggest moving the sensor a bit further up toward the line just before the "B" in Bosch. Certainly sounds like a sensor issue. To get the sensor closer put it on a different spoke that is further out if possible

speedy25

Find a dealer somewhere that actually has the interface and software. THEN you can find out the REAL error and fix it correctly. My guess would be a crappy speed sensor or damage to the sensor wire.
I had a customer come to me because his bike didnt work. he wasted a couple hours at another shop that strangely enough was listed for Bosch repair. I had the correct answer in 3 minutes. He had a failed battery that couldnt be revived.
I hope you find your problem easily.

-SP

speedy25

An admin should move this post over to the ebike group.

-SP

fooferdoggie 

no looking at the pic the magnet is just in the wrong position. the magnet needs centered on the line. I had no clue about the line either when I put a magnet on a new wheel. took it in cost me 30.00 to check it over and then just adjust the magnet. if that does not fix it then take it in. Now I have a Nyon that the mount tends to new a bit loose that can cause connection issues. but taking it off and putting it back on solves that issue.

veganbikes

This is a Bicycle Mechanics issue. Correct it is an e-bike but it is more related to this section.


Basically any shop can help out if they have a QBP account and a phone they have support. Obviously helpful to have the Bosch Diagnostic tool but I am sure a lot more shops have them these days. Sad your original shop cannot help but make sure you have all of your receipts and such. You might try adjustment of the magnet but looks like decent enough positioning.

You could also call another shop that is at least on the same coast and see if they can walk through it or give you some tips.