Help finding 200mm Centrelock Sram rotors in stock

[All Mountain Coaching]

Here is the RT-EM900 overlayed on the levo rotor. The magnet is further out but it does like it will still work.

View attachment 6716

what about height of the magnet. the specialized magnet bolts onto the 6 bolt, ending up about 3/4” proud of the rotor surface. this EM rotor appears to have the magnet tucked flush with the spokes.

also they are using ferrite magnet. why cut costs like that? beats me.

let us know if it works!

That's very true, one thing I noticed that was putting me off.

I've got 2x 10mmx4.5mm magnets arriving tomorrow that have a 2.5kg pull. Tomorrow is d day. Fingers crossed

 

[r23ves]

let us know if it works!

I can't test the bike at the moment but there doesn't seem to be any clearance issues and wheel rotation is picked up in the mission control app so its looking good.

 

[All Mountain Coaching]

Ok so the magnets arrived. Put one on in the below position, closest to the centre and next to an original bolt.

And set off. Power for 5 seconds then a red and blue light and power loss. Gutted! View attachment 6761 View attachment 6762

 

[All Mountain Coaching]

So there's a few different factors and it's the frustrating game of process of elimination.

Magnet location, strength and distance from the sensor.

 

[All Mountain Coaching]

So I did, or think I did, a factory reset just in case all these tests screwed something and put the magnet, totally out of position, but most secure (pic1). Fail. Same thing.

Then I put it in the most insecure place, it's barely contacting a 1/3rd of the magnet, but replicating pretty much where it would be using the OEM bracket and magnet. Fail.

I'm starting to think I'm pissing in the wind. That position couldn't be closer to the original IMO. So it's either sticking out too much, so I need a thinner magnet, or is the wrong strength.... Or something else?!?

 

[r23ves]

Or something else?!? View attachment 6769 View attachment 6770 View attachment 6771

At the risk of sounding like an idiot, does the polarity matter? It it the same way round as stock?

 

[ccrdave]

At the risk of sounding like an idiot, does the polarity matter? It it the same way round as stock?

yeah that what I was about to say but checking my levo magnet it sticks to the rotor so im sure @All Mountain Coaching has it the right way round but it is weird why it doesnt work!

 

[ccrdave]

it must be distance from the sensor is there any way you can cable tie the original to the disc just for a test

 

[khorn]

Can you somehow zip tie the stock magnet in approximately same location iot test if there is built in a microchip for authentication. I know it sounds far out but it seems like Specalized have gone over the top iot prevent tampering with the speed sensor signal(speed limits)

Karsten

 

[All Mountain Coaching]

Success!

I'll tell all shortly...

 

[Gary]

The suspense is killing...

 

[All Mountain Coaching]

Ok guys, I've never used magnets before so I'm guessing it's an easy mistake. I don't mind holding my hand up, even if it might make me look dumb.

So the magnet came in like a metal shell. I was sticking the magnet to the disc so the sensor couldn't pick it up. Luckily there was just enough pull to put the magnet on backwards and stick to the disc, tested... And then it worked. So I glued it in place with the 2 part epoxy and left it over night.

You'll see what I my mean on the two pics...

 

[All Mountain Coaching]

I also had the best outcome with the rotors. Took the ones off the Enve and they are 6 bolt fitment with 6 bolts?!? So I just put the levo ones straight on, no adapter needed and no centrelock rotor needed. All those are going back. I guess I should've just looked at it all first. I don't know why my hubs are like that. There's 6 pins and a lock ring. See pics. Only really noticeable when the lock ring is off.

So I'm a happy bunny... And over £100 better off.

Total cost...£3 for magnets from rs components and £5 for 2 part epoxy glue from Screwfix.

 

[All Mountain Coaching]

Thanks to everyone that pitched in to help.

I also had the lightest outcome too. I weighed the 180 rotors, 200s, 200 centrelock and 200 with adapter. Pics below for reference.

 

[All Mountain Coaching]

Keep us posted. If these work then it's another option for people needing a new rotor.

 

[All Mountain Coaching]

That's interesting. There's a few places in the UK that stock the 203 em900 rotor. It's a hefty £69. A centerline at £30, plus £3 magnets, £5 glue is quite appealing, but not as trick.

 

[r23ves]

i installed it and it does work. im returning it and im going to wait for the 203mm.

How well did you test? The em900 seems to work for me initially but cuts out sometimes with the LED lights on the top tube showing "motor error". The disc seems like the likely culprit.

 

[r23ves]

My child didn't look to impressed when I canabilised one of his toys to extract a magnet
But I stuck it on top of the existing em900 magnet and that fixed the issue. So it must be just slightly too far out of range to reliably register with the sensor.

Doesn't seem worth it pay more for the em900 if you have to do gluing anyway.

 

[ccrdave]

can you not just mount it the other side of the disc to where its bolted on

 

[r23ves]

can you not just mount it the other side of the disc to where its bolted on

Not sure, I think the plastic bracket might interfere with the lock ring. Will check later.

 

[ccrdave]

yeah i meant the little bracket that holds the magnet on

 

[Lad]

In case some Focus owners are going to play with rear rotors:
The OEM setup uses 6 bolt rotor with a third party magnet holder like this:

If changing to centerlock wheel, the Shimano rotor with integrated magnet can be used, but the magnet is either too weak or it is offset way back compared to the pic above. It may work on other bikes, on Focus it will give W011 error (no speed data detected).

Solved this with a small neodymium magnet with M3 countersink hole thru it (got it on eBay from China, cost peanuts, used them for some other DIY job).

Used JB Weld steel epoxy (saved my bacon few times in my moto days), it is tough stuff.
Made around 500km with the mod, holds well, I think that plastic magnet cavity will break before magnet gets undone. Rock solid.

 

[urastus]

Ok so the magnets arrived. Put one on in the below position, closest to the centre and next to an original bolt.

And set off. Power for 5 seconds then a red and blue light and power loss. Gutted! View attachment 6761 View attachment 6762 View attachment 6763

I was just reading through this post - I'm gluing a magnet too. I think your problem above is that the magnet is up against the lock ring. The lock ring is magnetic - I think you've made the lock ring an extension of the magnet! The sensor wouldn't work with that - I think it wouldn't record any movement.

As an aside, I measured my shimano rotor with magnet - 68mm diameter. The rotor was still on the wheel on the bike so I used verniers. Essentially, 34mm from center of rotor; easy while holding ruler across centre of rotor.