First ebike conversion & Newbie

John Mumby

Finding my (electric) wheels
Dec 2, 2018
5
0
50
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

file-84.jpeg
 

Laser Man

Pedelecer
Jul 1, 2018
196
122
Michelmersh SO51
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 -
PP1020116.JPG
The spacer looks like this -
pP1020128.JPG
Can't help with the grumbly gears
 

scott gaza

Pedelecer
Oct 20, 2018
162
24
scone
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

Finding my (electric) wheels
Dec 2, 2018
5
0
50
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

Finding my (electric) wheels
Dec 2, 2018
5
0
50
47CE96F5-2504-4108-B9A8-860E4DC6C2BF.jpeg
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

Esteemed Pedelecer
May 23, 2015
15,971
6,292
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 ;)
DSC_0110.JPG
 

Laser Man

Pedelecer
Jul 1, 2018
196
122
Michelmersh SO51
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

Pedelecer
Sep 5, 2018
53
20
70
Crete
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

Pedelecer
Oct 20, 2018
162
24
scone
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
 
Last edited: