Speed pickup - tight chain stays

Anybody experienced the chainstays being so close to the wheel you can't get the speed pick up in?

I found positioning the speed sensor vey fiddly - eventually, after a lot of speed sensor error messages, a couple of very thin zipties through those tiny slots helped secure it into a position that works. Maybe compress a sticky pad or two, or fashion a small triangular wedge of some material, glued and held tight with zipties between the sensor and the chainstay, a little further to the right?

 

It'd be helpful, if there was an extension mount which could rotate and lock into position.

 

https://www.amazon.co.uk/TorqueTech-Extended-Mounting-Bracket-Extension/dp/B07T9G4SJ1/ref=

Try the mount on the outside of the stay with the sensor on top /not the best but a workaround

This is the furthest apart I can get them with the supplied mount and it's still hitting. There is a kick stand bracket underneath which is annoying.

If I were desperate, and couldn't find any other way to mount this sensor, I might try cutting a longish thin piece of rust-proof metal, araldite the speed sensor mount to it (red in pic below) and attempt to secure it to the chainsay using a couple of zipties situated further up (black in pic below). The double sided sticky tape adhesive under the speed sensor mount can be dissolved using any oil, which of course you would have to use alcohol or something similar to remove, before using araldite. If the position is correct, araldite it to the chainstay in it's final position? Araldite is hard to remove and if it didn't work, you might need a new speed sensor mount, plus the paintwork would be damaged if you bonded the metal piece to the chainstay... therefore I hope you can find a better bodge. Maybe try securing the long metal piece to the chainstay using sticky pads and zipties first?

 

 

Edited September 17, 20223 yr by guerney

So, slept on it and turned the pickup around and put the magnet on a spoke on the opposite side. Seems to with, light blinks, no errors. Although my controller speed seems to read garbage. Don't know if that's related.

Extension cable:

 

https://www.amazon.co.uk/Almabner-Extension-Electric-Sensor-Bafang/dp/B083XVT71Q/ref=

Cable length isn't the issue. The issue is that my chain stays are so close to the spokes there wasn't room. This set up seems to work.

The magnet needs to be about 1mm away, the sensor light switching off and on apparently isn't enough, the magnet needs to be closer than in the photo. Mine was fiddly to set up, after altering the angle of the end of the speed sensor a bit using zipties - the sensor isn't perfectly parallel to the magnet, but I eventually got it close enough to get accurate speed readings on the display. Too much flex at the cable makes me nervous. Internal wires could break over time.

The nice thing about 4:1 self-adhesive heat shrink, is that once the hot glue within cools down, it sets into shape - there would still be strain on the internal wires at the bend but it wouldn't move around as much, therefore still isn't ideal. You want a straight cable run, which is why I linked up an extension cable.

 

I don't trust IPV ratings, and I'm often cycling in the rain for hours, therefore I've waterproofed all the connectors on my bike using this or self-amalgamating rubber tape.

 

https://www.ebay.co.uk/itm/203043868181

The magnet needs to be about 1mm away, the sensor light switching off and on apparently isn't enough, the magnet needs to be closer than in the photo. ------ close enough to get accurate speed readings on the display.

OK so that's interesting. I was presuming that light blinking and no error codes meant all was good.

The issue is that if I put it on a spoke on the near side it smashes into the sensor. Maybe if I used an extender I could try placing it on the seat stays.

Have you set the wheel size on the display makes big diff to speed displayed

Yes I set the wheel size.

OK if wheel size is ok . Then magnet needs to be closer to the sensor

One can place another magnet on top of the spoke magnet to close the gap, my bbs worked ok at 5mm spacing.

If you've got some old inner tube, maybe wrap some around the chainstay, build it up a bit, then very tightly ziptie the sensor on to bring the it closer to the magnet? If it works, maybe glue the inner tube wrap to itself? I wouldn't glue it to the chainstay directly, as that would damage the paintwork.

Edited September 18, 20223 yr by guerney

The distance can be critical with many sensors. Too close and you get garbage, too far and nothing. You will need to experiment with the distance, but in any case it must be less than 7mm. Set the bike up so you can observe the display as you turn the wheel, the display should give you the mph. Ideally for most sensors 2-4mm is the correct distance.

Don't fix anything permanently until you ascertain the correct distance for your particular sensor/magnet combination. I experimented with mine until I found turning the sensor through 90degrees so the cable exit was vertical and the distance was 2mm gave me the best result.

Another sleep, another plan. This one seems to have worked. Chopped the back of the bracket and reversed it so it sits on the outside of the chain stay. I can now get the correct distance and it's working fine. (Yes I have secured the probe in the bracket) Thanks all for the input.

Glad it’s sorted ,, the sensor is only a reed switch , the magnet “pulls” both contacts together , as it’s travelling at “speed” makes the controls box think it’s permanently switched on . ( for them with more knowledge than me , I give it in layman’s terms ). So if you naff-it up it is easy to make a new one only costing less than a quid

Another sleep, another plan. This one seems to have worked. Chopped the back of the bracket and reversed it so it sits on the outside of the chain stay. I can now get the correct distance and it's working fine. (Yes I have secured the probe in the bracket) Thanks all for the input.

[ATTACH type=full" alt="48903]48903[/ATTACH]

 

[mention=19370]peter.c[/mention] was right again in post #3