First ebike conversion & Newbie

[John Mumby]

Hi All

I am new to this forum, so hello to all.

I have converted my mountain bike and have a couple of questions.

Firstly I dont think the rear cassette that came with my hub motor is compatible with my current chain/chainset, I,m running XT, its grumbly when pedalling, I tried to change the cassette but its not the same fitment, does anyone know if a suitable cassette can be purchased?

Second question is i want to use the pedal assist sensor but there is no gap between the crank arm and bottom bracket the XT uses a hollow BB so the magnetic disc wont fit in, plus the BB is too big for the magnetic disc to fit over it, is there a way around this?

Just like to add I am made up with my conversion so far and the electric bug is biting me hard.

Thanks John

 

[Laser Man]

For the pedal sensor -
Enlarge the hole in the magnet disc so that it fits over the bottom bracket (dremel, hole saw etc.).
Then glue the magnet disc to the granny chain ring : from your picture the chain ring is small, so you will probably need to make up a spacer like I did.
If the sensor bracket will fit as it is then great, but otherwise you will need to fix the sensor to the seat tube.
Here's a picture of my setup -

The spacer looks like this -

Can't help with the grumbly gears

 

[scott gaza]

Hi John, I think you have 9spd+ running gear on your bike. As such you would need to change over to the correct speed ie:7-8 spd sorry but that's a minimum new chain but probably mech's and chain rings as well. The only good news is that they are much cheaper than 9spd+ components.

 

[John Mumby]

Thank you

So you have the sensor attached to the frame and the mag disk glued to the low gear and a spacer to bring them closer together, is that correct?

How close do they need to be 1-2mm?

Thanks again

 

[John Mumby]

Hi John, I think you have 9spd+ running gear on your bike. As such you would need to change over to the correct speed ie:7-8 spd sorry but that's a minimum new chain but probably mech's and chain rings as well. The only good news is that they are much cheaper than 9spd+ components.

Thanks Scott

That’s a ball ache but it makes sense, your right it is 9 speed.


Why does this make a difference are the profiles of the 9 speed teeth and chains different to the 7-8 speed gears/chains?

 

[soundwave]

if you have a 9spd cassette then you need a 9spd chain cant mix n match without problems.

with a 12spd chain its so narrow it locks on to the sprocket

 

[wheeliepete]

Your motor prob. has screw-on freewheel, so you could fit one of these if your drop outs are wide enough.

https://www.aliexpress.com/item/Okfeel-BYDNP-EPOCH-ZF32T-Freelwheel-7-8-9-speed-Mountain-Bike-Bicycle-Fly-Wheels-rotate-21/32874957169.html?spm=2114.search0604.3.1.22a3187fej0x4z&ws_ab_test=searchweb0_0,searchweb201602_5_10065_10068_10130_10547_319_317_10548_10696_10192_10190_453_10084_454_10083_10618_10307_10820_10301_10821_10303_537_536_10059_10884_10887_100031_321_322_10103,searchweb201603_51,ppcSwitch_0&algo_expid=be074dda-f37d-429c-a70e-27d0500ab748-0&algo_pvid=be074dda-f37d-429c-a70e-27d0500ab748

 

[John Mumby]

Your motor prob. has screw-on freewheel, so you could fit one of these if your drop outs are wide enough.

https://www.aliexpress.com/item/Okfeel-BYDNP-EPOCH-ZF32T-Freelwheel-7-8-9-speed-Mountain-Bike-Bicycle-Fly-Wheels-rotate-21/32874957169.html?spm=2114.search0604.3.1.22a3187fej0x4z&ws_ab_test=searchweb0_0,searchweb201602_5_10065_10068_10130_10547_319_317_10548_10696_10192_10190_453_10084_454_10083_10618_10307_10820_10301_10821_10303_537_536_10059_10884_10887_100031_321_322_10103,searchweb201603_51,ppcSwitch_0&algo_expid=be074dda-f37d-429c-a70e-27d0500ab748-0&algo_pvid=be074dda-f37d-429c-a70e-27d0500ab748

Hi Pete

Its not a screw on, the hub motor cassette fits on wide splines with two different sizes on the hub so gears 1-3 have a larger bore and 4-7 smaller bore if that makes sense!

 

[Laser Man]

Thank you

So you have the sensor attached to the frame and the mag disk glued to the low gear and a spacer to bring them closer together, is that correct?

How close do they need to be 1-2mm?

Thanks again

On my setup I needed the spacer to keep the magnet disc clear of the chain - even with the spacer there is only just enough room. I think my granny chain ring has 22 teeth - if yours has more teeth (bigger diameter) then you might get away without the spacer.
The sensor should be 5mm or less away from the magnet ring - ideally 2 to 3mm. On mine it is about 1mm because everything is so cramped.

 

[jeff St.Clair]

Yeah I had to glue the magnet disc to the granny cog on my Rockhopper ,I used a two part epoxy ,then I made a new bracket for the sensor that I fastened under the plastic guide for the gear cables under the bottom bracket ..I had to get the gap down to 1.5 mm before the pas would work properly...even then I found the pas not very smooth cutting in and out ...mine has eight magnets ...but I found by setting the controller to twelve magnets ...it worked much smoother ???...one day I will up -grade to a twelve magnet disc .....

 

[scott gaza]

View attachment 27984


Thanks Scott

That’s a ball ache but it makes sense, your right it is 9 speed.


Why does this make a difference are the profiles of the 9 speed teeth and chains different to the 7-8 speed gears/chains?

Hi John, the profile/spacing is the same but the width of chain and sprocket spacing are different, also a 7-8 speed chain might not go through a 9spd derailleur without catching. soz Gaz