Pedelec sensor - missing magnets

[Phil the drill]

Hi,

I just discovered that the rather 'lumpy' power delivery on the pedelec system of my 905se is down to magnets having seemingly fallen out of the disc on the pedal crank. Is this a common problem? is it worth keeping a spare disc? - I don't know how much they cost, but since my bike is only 5 months old @ present I'm assuming they are covered under warranty (I haven't contacted ETS yet, where I bought the bike).
One question though: When I replace the disc, it looks like a simple job to put it back on the left crank, rather than the right, and to move the sensor to the left also. Will it work if I do this, or will it 'think' I am backpedalling and fail to energise the system? I'm not sure if the system senses direction of travel by measuring uneven gaps in the placement of magnets?
If it is possible to move the sensor system over to the left side, then I can fit a proper chainguard over the chain on the right - and - bingo oily trouser problem sorted!!
Incidentally if it does sense direction by measuring gaps between magnets, is it possible to obtain mirror image discs?

Cheers, Phil.

 

[carpetbagger]

when i first got my powabyke there was a squeaking every so often,i traced to the magnets rubbing against the sensor. i adjusted the disc and everything has been ok since then but i do periodically inspect it

 

[Blew it]

Phil,

There should be 5 magnets in the disc, Sorry, I don't know the answer to your other question.

Bob

 

[Andrew harvey]

I've tried that one before, to lazy to do it properly.
You'll keep knocking the sensor and eventually have to bite the bullet and swap it over. It is no hassle to fit it onto the chain side, unless you have fancy chain guards, or a lack of clearance.
They are normally polarised, try pedalling backwards.

If for some reason you can not fit it to the chain wheel try swapping the magnets, use a good glue.

 

[Phil the drill]

It is no hassle to fit it onto the chain side, unless you have fancy chain guards, or a lack of clearance. They are normally polarised, try pedalling backwards.

If for some reason you can not fit it to the chain wheel try swapping the magnets, use a good glue.

Hi, it is already on the chain side on the 905se, I'm wanting to move it to the other side, so I can fit a fancy chain guard!
Pedalling backwards - on a pedelec and freewheel hub !! I don't think so. I reckon I'd be giving less than minimal assistance to the motor that way!
Cheers, Phil

 

[flecc]

You can put it on the left as long as you can reverse the disc so that the same magnet pole is facing the sensor. The direction of rotation doesn't matter.
.

 

[Phil the drill]

You can put it on the left as long as you can reverse the disc so that the same magnet pole is facing the sensor. The direction of rotation doesn't matter.
.

Many thanks, Flecc.
Now I should be able to avoid that 'well oiled trouser' feeling and get some peace at home to boot.....
Cheers, Phil

 

[ElephantsGerald]

Now I should be able to avoid that 'well oiled trouser' feeling and get some peace at home to boot.....

Hi Phil,

I'd be interested to know what chain guard you end up fitting. I'm slowly running out of trousers that aren't covered in oil

Regards,

Elephants

 

[Phil the drill]

Hi Phil,

I'd be interested to know what chain guard you end up fitting. I'm slowly running out of trousers that aren't covered in oil

Regards,

Elephants

Hi Elephants,

What started as a rather modest dream (just keep the trouser bottoms oil free) is turning out to be something of a nightmare. I spotted what looked to me to be an ideal chainguard in my local bike shop - it attaches to the bottom bracket, held in place by the outer ring of the bracket, surrounds the chainring and extends a fair way back over the upper part of the chain. So far so good. To fit it would require moving the pedelec sensor ring to the left (seems pretty straightforward) and putting the disc with the magnets on the left crank. Now for the hard part.......the owner of the local bike shop only has one in size 46-50t. The original Wisper is 52t (mine has been modified to 42t), hence it won't fit. He is reluctant to tell me who makes it, insists that it is a 'professional' job to fit and says if I bring my bike in he will see if it can be made to fit and if so order me one in the correct size prior to fitting it.
I, on the other hand, am completely prepared to take the risk of fitting it myself and am too mean to pay him (quite a lot) to do a job which I am perfectly capable of doing myself. He won't order me one unless I let him fit it, nor will he tell me who makes them or where I can get them from....Oh dear, we have an impasse..........
In a nutshell, until one of us cracks (sorry about that!) I'm going nowhere with this.
If anyone out there knows of the whereabouts of this type of chainguard, I'd be delighted to know and will post pictures of finished results when available!

Cheers, Phil

 

[the_killjoy]

Did the 42 fit without trouble ~ is it standard chainwheel, I could do with a bit more speed on the flat.

 

[Phil the drill]

Did the 42 fit without trouble ~ is it standard chainwheel, I could do with a bit more speed on the flat.

Hi Killjoy,

The 42t chainring is a standard single ring 5 hole 110bcd ring, and as such fits easily in place of the standard 52t one. I sourced mine form SJS, over the internet.
A couple of points though
1) A 42t ring will give you less speed on the flat not more, since you are reducing the circumference of the front ring. I fitted mine to improve the hill climbing ability of my 905se - I found it to be overgeared for the many nasty switchback climbs on the narrow lanes around me.
2) I combined mine with a change of rear cassette to an 11t-34t one. These are difficult to get hold of, but in my opinion worth it. In combination with the chain ring above you will get significantly lower gearing for the hills, combined with a slight increase in speed in top gear. In other words, increased gear range.
3) If you fit a smaller front chainring on the 905se it is likely to keep falling off in the low gears, due to the angle of the chain path. This is easliy solved by bolting the new chainring on the inside of the crank bracket (as though it were a 2nd ring) rather than in the top gear position on the outside.
4) The plastic chain guard won't fit the ring, but is easy source cheap and equally ineffective chainguards - if you really want one. A 'proper' one would be nice, but that's a whole different story.....(see above).

Cheers, Phil

 

[the_killjoy]

I realised after I posted that I had the comment on gearing round the wrong way ~ It had been a long day.

 

[ElephantsGerald]

2) I combined mine with a change of rear cassette to an 11t-34t one.

Hi Phil,

How did you deal with the motor wire coming out of the axle when you fitted the new 11-34T freewheel?

Did you cut the cable, or did you undo all the connections at the controller?

Regards,

Elephants

 

[Phil the drill]

Hi Phil,

How did you deal with the motor wire coming out of the axle when you fitted the new 11-34T freewheel?

Did you cut the cable, or did you undo all the connections at the controller?

Regards,

Elephants

Hi Elelphants,

I unclipped the wire from the frame, traced it into the wiring box and just disconnected it there. The wiring's rather tight so its a bit of a squeeze getting it all back in again afterwards, but its not too hard.
What you will have to watch is the tool you use to undo the cassette - Shimano's own, and the the Park one won't work because the axle diameter is too great to fit through the hole in the centre of the tool. Drilling that hole out is almost impossible as the alloy is so hard. I have a (cheaper) alternative made by Cyclepro (CPT203) which has a square hole designed to take a socket driver (not needed as you usually just clamp it in a vice and turn the wheel to remove the cassette), which is large enough for the axle and wiring to be easily threaded through.

Hope that helps, cheers Phil

 

[BrizzleBoy]

Hi Phil,

I'd be interested to know what chain guard you end up fitting. I'm slowly running out of trousers that aren't covered in oil

Regards,

Elephants

I dont know why but that tickled me

 

[Mussels]

Hi 4) The plastic chain guard won't fit the ring, but is easy source cheap and equally ineffective chainguards - if you really want one. A 'proper' one would be nice, but that's a whole different story.....(see above).

I have found the plastic guard is essential on the 52 teeth chainring to stop the chain falling off, I managed about 100 feet until it dropped off the inside. Incidentally I am now running a 36 tooth chainwheel with the original freewheel and it is much better, I use all the gears and can still pedal up to about 25mph. I have a suntours 13-28 freewheel waiting to be fitted but I have to wait for the toolkit to arrive to do that.

Back to the subject - my pedelec sensor is broken, I suspect it was my chain derailing that did it. I'm looking at alternatives and a thumb switch on the left hand grip is tempting, what does the controller look for from the pedelec switch - is it just a closed circuit or does it need a constanty switching circuit?
Edit: answered my own question now, the magnets are not evenly spaced and the controller knows if I'm back pedalling. Not going to be an easy one to get round.

 

[Mussels]

I'm getting individual tools now, can someone tell me if this will fit the Megarange freewheel on the Wisper? The internal diameter is good but I'm not sure if all Shimano Freewheels use the same tool. It says Uniglide but is pictured with a Hyperglide sprocket and I'm suspicious.
Park Tools FR1C Uniglide Shimano

 

[Phil the drill]

I'm getting individual tools now, can someone tell me if this will fit the Megarange freewheel on the Wisper? The internal diameter is good but I'm not sure if all Shimano Freewheels use the same tool. It says Uniglide but is pictured with a Hyperglide sprocket and I'm suspicious.
Park Tools FR1C Uniglide Shimano

Are you sure that the axle will fit through this tool? I bought a Park one and the oversized axle on my motor would not fit through the centre of the tool. It is almost impossible to drill this out as the alloy is so hard. I used the cyclepro equivalent (link: Cyclepro Multi Freewheel Remover Shimano Uniglide Cycle Accessories Workshop Bicycle Tools General Maintenance Cyclepro Multi Freewheel Remover Shimano Uniglide ). This is a well made equivalent, fits and the axle goes though it, plus you can use a socket set on it if you don't wish to go through the normal routine with a bench vice. Oh, it's cheaper too!

Cheers, Phil

 

[Mussels]

Are you sure that the axle will fit through this tool? I bought a Park one and the oversized axle on my motor would not fit through the centre of the tool. It is almost impossible to drill this out as the alloy is so hard. I used the cyclepro equivalent (link: Cyclepro Multi Freewheel Remover Shimano Uniglide Cycle Accessories Workshop Bicycle Tools General Maintenance Cyclepro Multi Freewheel Remover Shimano Uniglide ). This is a well made equivalent, fits and the axle goes though it, plus you can use a socket set on it if you don't wish to go through the normal routine with a bench vice. Oh, it's cheaper too!

Cheers, Phil

I'll go with the cheaper option and stop arguing.

 

[torrent99]

Irratic pedelec on Wisper 905se

This morning on the way in to work my pedelec started acting up in a similar way to what's described here (lumpy, irratic, pulsating power).

Did anyone ever manage to get a solution?

Cheers

Steve