Carrera Crossfire/Vulcan Torque sensor

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I recently stripped one down so i can describe how it works.

To disassemble it, you take the crank/chainwheel off, then remove the 4 screws in the back. There's 4 shim washers in there, so be careful not to lose any. The sensor is held on with three small screws.

The sensor is partly mechanical and partly electronic. There are two adjacent castellated ridges. One is fixed to the crank and the other to the chainwheel, and there are springs between them. They line up together when there's no load, but when there's load on the crank, one moves out of phase from the other against the springs, so the gap between the castellations decreases. The sensor is optical. It measures the frequency and size of the gaps, and sends that info to the controller so that it knows how dast and how hard you're pedalling.

To me, the whole arrangement is a bit rough. It's too easy to get dirt in there, which will mess up the optics. Mine was full of dirt. I don't think it's a good idea to use one of these in salty winter conditions or anything that involves mud. I can see the need to regularly disassemble and clean all the parts, especially the slots in the sensor.

The main mechanical part:
20180216_151643.jpg

The cover plate to which the sensor attaches over the little window (right of photo). Note the shims:

20180216_151651.jpg

The sensor:

20180217_233435.jpg

The middle part of the cover-plate is free to rotate relative to the outer part, but the sensor screwed to it has two anti-rotation lugs to hold it still while the outer rotates with the chainwheel. Mine has a lug broken off:

20180217_233412.jpg
 

egroover

Esteemed Pedelecer
Aug 12, 2016
970
575
56
UK
Fascinating d8veh, thanks for sharing. That one is seriously caked in s$£t, no wonder it was playing up. I sometimes think that the Suntour HESC system is too clever for it's own good, and partly the reason why I wanted to trade my old crossfire-e in for a new one and get another 2 year warranty (although happy to report didn't use it on my old bike)
 

dedPiksil

Finding my (electric) wheels
Sep 5, 2017
7
2
39
London
I recently stripped one down so i can describe how it works.

To disassemble it, you take the crank/chainwheel off, then remove the 4 screws in the back. There's 4 shim washers in there, so be careful not to lose any. The sensor is held on with three small screws.

The sensor is partly mechanical and partly electronic. There are two adjacent castellated ridges. One is fixed to the crank and the other to the chainwheel, and there are springs between them. They line up together when there's no load, but when there's load on the crank, one moves out of phase from the other against the springs, so the gap between the castellations decreases. The sensor is optical. It measures the frequency and size of the gaps, and sends that info to the controller so that it knows how dast and how hard you're pedalling.

To me, the whole arrangement is a bit rough. It's too easy to get dirt in there, which will mess up the optics. Mine was full of dirt. I don't think it's a good idea to use one of these in salty winter conditions or anything that involves mud. I can see the need to regularly disassemble and clean all the parts, especially the slots in the sensor.

The main mechanical part:
View attachment 23426

The cover plate to which the sensor attaches over the little window (right of photo). Note the shims:

View attachment 23427

The sensor:

View attachment 23428

The middle part of the cover-plate is free to rotate relative to the outer part, but the sensor screwed to it has two anti-rotation lugs to hold it still while the outer rotates with the chainwheel. Mine has a lug broken off:

View attachment 23429
Hi d8veh, just browsing and I stumbled upon your post. I too have a lug broken off the sensor casing. How are you holding it in place so it's locked to the small metal bracket?
 

John Barnes

Just Joined
Jun 14, 2018
3
3
uk
Hi d8veh, just browsing and I stumbled upon your post. I too have a lug broken off the sensor casing. How are you holding it in place so it's locked to the small metal bracket?
I fixed that problem ...that sensor casing is very weak and in a bad spot.
I first rotated the small metal bracket clockwise about 20 Deg then made a new steel lug in 3 mm zintec steel fastened on with m4 a2 screws, I drilled two holes in the back plate to the right of the sensor, the original sensor broke a lug when the chain fell off as it seems the Vulcan e has a sloppy chain on the small tooth sprockets. You could rotate the whole assembly away from where the chain could hit it, say inline with the stay.
 
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Milky bar kid

Just Joined
Feb 10, 2019
2
1
I recently stripped one down so i can describe how it works.

To disassemble it, you take the crank/chainwheel off, then remove the 4 screws in the back. There's 4 shim washers in there, so be careful not to lose any. The sensor is held on with three small screws.

The sensor is partly mechanical and partly electronic. There are two adjacent castellated ridges. One is fixed to the crank and the other to the chainwheel, and there are springs between them. They line up together when there's no load, but when there's load on the crank, one moves out of phase from the other against the springs, so the gap between the castellations decreases. The sensor is optical. It measures the frequency and size of the gaps, and sends that info to the controller so that it knows how dast and how hard you're pedalling.

To me, the whole arrangement is a bit rough. It's too easy to get dirt in there, which will mess up the optics. Mine was full of dirt. I don't think it's a good idea to use one of these in salty winter conditions or anything that involves mud. I can see the need to regularly disassemble and clean all the parts, especially the slots in the sensor.

The main mechanical part:
View attachment 23426

The cover plate to which the sensor attaches over the little window (right of photo). Note the shims:

View attachment 23427

The sensor:

View attachment 23428

The middle part of the cover-plate is free to rotate relative to the outer part, but the sensor screwed to it has two anti-rotation lugs to hold it still while the outer rotates with the chainwheel. Mine has a lug broken off:

View attachment 23429
Hi what tools are needed to remove this please.
 

Paddy Druid

Finding my (electric) wheels
Oct 28, 2019
7
1
I recently stripped one down so i can describe how it works.

To disassemble it, you take the crank/chainwheel off, then remove the 4 screws in the back. There's 4 shim washers in there, so be careful not to lose any. The sensor is held on with three small screws.

The sensor is partly mechanical and partly electronic. There are two adjacent castellated ridges. One is fixed to the crank and the other to the chainwheel, and there are springs between them. They line up together when there's no load, but when there's load on the crank, one moves out of phase from the other against the springs, so the gap between the castellations decreases. The sensor is optical. It measures the frequency and size of the gaps, and sends that info to the controller so that it knows how dast and how hard you're pedalling.

To me, the whole arrangement is a bit rough. It's too easy to get dirt in there, which will mess up the optics. Mine was full of dirt. I don't think it's a good idea to use one of these in salty winter conditions or anything that involves mud. I can see the need to regularly disassemble and clean all the parts, especially the slots in the sensor.

The main mechanical part:
View attachment 23426

The cover plate to which the sensor attaches over the little window (right of photo). Note the shims:

View attachment 23427

The sensor:

View attachment 23428

The middle part of the cover-plate is free to rotate relative to the outer part, but the sensor screwed to it has two anti-rotation lugs to hold it still while the outer rotates with the chainwheel. Mine has a lug broken off:

View attachment 23429
Hi, Im new.
Can I buy this somewhere? Or a throttle kit for my Vulcan e?
Thanks
 

skunkyman

Finding my (electric) wheels
Jul 4, 2020
6
0
You can remove the sensor without removing the chainset, but each to our own. This is a common problem which suntour has none about for some time now. I've read a lot of complaints about the torque sensor. I took mine off before it broke and used some araldite to strengthen the locating lugs.
 

egroover

Esteemed Pedelecer
Aug 12, 2016
970
575
56
UK
You can remove the sensor without removing the chainset, but each to our own. This is a common problem which suntour has none about for some time now. I've read a lot of complaints about the torque sensor. I took mine off before it broke and used some araldite to strengthen the locating lugs.
Sensor available to buy here
 

mn6200

Just Joined
Nov 27, 2020
1
0
Does anyone know if it's possible to get a new backplate for one of these? The rubber seal has disintegrated on mine :(