# Are spoke magnets universal?



## deviousalex (Aug 18, 2010)

Will they work with any speed sensor? I would think so, but I'd rather double check than buy something useless.


----------



## RUFUSPHOTO (Oct 14, 2010)

Yes they are.


----------



## MR_GRUMPY (Aug 21, 2002)

Unless you have bladed spokes. Then, you need a magnet made for this type of spoke. The traditional "Dot" magnet will not fit on a bladed spoke, because of the shape of the spoke.
.
.


----------



## FBinNY (Jan 24, 2009)

A magnet is a magnet. They may vary in size or strength, and spoke mounting system, but from an operational standpoint they're all the same. 

What matters to the sensor is that the magnet passes the right area and is close enough to be sensed as it goes by.


----------



## stevesbike (Jun 3, 2002)

magnets have polarity - put the wrong one between a carbon fork and a sensor and the field generated can make the carbon explode...


----------



## FBinNY (Jan 24, 2009)

stevesbike said:


> magnets have polarity - put the wrong one between a carbon fork and a sensor and the field generated can make the carbon explode...


It gets so hard to tell these days, but I sure hope you're being facetious.


----------



## cohiba7777 (Jul 6, 2006)

Interesting question - I am now running Kyserium SL wheels with bladed spokes and even though I ordered the bladed spoke magnet (from Mavic) it isn't staying 'found' by my Garmin 705 sensor. Been to bike shop once already & going back again - very frustrating. Not sure if it's the Garmin, maybe my battery in the sensor itself - magnets are magnets I agree - no reason shouldn't work.:mad2:


----------



## FBinNY (Jan 24, 2009)

cohiba7777 said:


> Interesting question - I am now running Kyserium SL wheels with bladed spokes and even though I ordered the bladed spoke magnet (from Mavic) it isn't staying 'found' by my Garmin 705 sensor. Been to bike shop once already & going back again - very frustrating. Not sure if it's the Garmin, maybe my battery in the sensor itself - magnets are magnets I agree - no reason shouldn't work.:mad2:


Be sure the magnet's track crossed the sensor at the right height. 

Years age when i sold Sigma computers, errors in track height were a regular problem. Sigma's reed switch was a seesaw, and when consumers very carefully set the magnet to pass right through the middle of the sensor it wouldn't work because it was passing the fulcrum so the switch didn't move.


----------



## JCavilia (Sep 12, 2005)

FBinNY said:


> A magnet is a magnet. They may vary in size or strength, and spoke mounting system, but from an operational standpoint they're all the same.
> 
> What matters to the sensor is that the magnet passes the right area and is *close enough to be sensed* as it goes by.


And keep in mind that the way in which the magnet is "sensed" by the sensor is rather simple and crude. The sensor is simply a reed switch, with a spring-loaded contact that is pulled by the magnet to close the circuit when the magnet is near, and then springs open again when the magnet goes away. The strength of the magnetic field in the vicinity of the switch, and the time it stays that strong, are the only important variables, and those are determined by the strength of the magnet and how close it gets. If your system is acting up, go to Radio Shack and buy a little rare-earth magnet, and attach it with a ziptie and some silicone sealant. Get it close enough and it will work. Of course, with a wireless unit the battery in the sensor assembly has to be good, too, or the signal won't get to the computer.


----------



## FBinNY (Jan 24, 2009)

JCavilia said:


> ....and the time...


A good and often forgotten point. There's a certain amount of time required by the reed switch to close and register the magnet's pass. If it goes by too fast it can pass without registering.

For that reason, you'll get better results with the sensor fairly low and the magnet closer to the hub where it's linear speed is lower.


----------



## MR_GRUMPY (Aug 21, 2002)

I've never had a problem with the magnet going by too fast. I always put the magnet about two inches from the rim (rear wheel) so that all my wheels are interchangable.


----------



## Kontact (Apr 1, 2011)

deviousalex said:


> Will they work with any speed sensor? I would think so, but I'd rather double check than buy something useless.


Sigma computers use a much more powerful magnet, and won't work with others. So they aren't universal, but pretty much.

You can buy a rare earth magnet and epoxy it to a spoke, if need be.


----------



## pmf (Feb 23, 2004)

MR_GRUMPY said:


> I've never had a problem with the magnet going by too fast. I always put the magnet about two inches from the rim (rear wheel) so that all my wheels are interchangable.


Me too, although mine is a little further down. Every bike my wife and I have has the sensor in exactly the same place so any front wheel will work on any bike. 

We had Spinergy Rev-X wheels years ago And I ended up gluing a piece of magnet to them with tubular tire cement. It worked just fine. A magnet is a magnet, no matter how it's attached.


----------



## MR_GRUMPY (Aug 21, 2002)

I still have a set of Rev-X on my old steel Bianchi RC, that I had to attach the magnet with tape.


----------



## tihsepa (Nov 27, 2008)

Get several magnets. The more the better. 

I usually run at least two but if I am going to race three or more is the norm.


----------



## pmf (Feb 23, 2004)

MR_GRUMPY said:


> I still have a set of Rev-X on my old steel Bianchi RC, that I had to attach the magnet with tape.


I haven't ridden mine in years. I sold my wife's set on ebay for $415.00 last year.


----------



## ROAD&DIRT (Mar 27, 2009)

A magnet is a magnet and will work with any sensor... mine will also work with standard and bladed spokes.


----------



## Kontact (Apr 1, 2011)

ROAD&DIRT said:


> A magnet is a magnet and will work with any sensor... mine will also work with standard and bladed spokes.


So you've tried this on a Sigma?


----------



## deviousalex (Aug 18, 2010)

I've managed to attach the Standard Garmin magnet to a set of Easton EA90s with bladed spokes even though the magnet is meant for standard spokes.


----------



## ROAD&DIRT (Mar 27, 2009)

Yes my cateye magnet works with my Sigma and vise versa.... I have the following two computers

View attachment 249006


View attachment 249007


----------



## paulfeng (Jun 10, 2011)

stevesbike said:


> magnets have polarity - put the wrong one between a carbon fork and a sensor and the field generated can make the carbon explode...


As a physicist, I need to correct an error in this statement.

"explode..." should read "asplode..."


----------



## nightfend (Mar 15, 2009)

Magnets are so two years ago...


----------



## FBinNY (Jan 24, 2009)

cohiba7777 said:


> Interesting question - I am now running Kyserium SL wheels with bladed spokes and even though I ordered the bladed spoke magnet (from Mavic) it isn't staying 'found' by my Garmin 705 sensor. Been to bike shop once already & going back again - very frustrating. Not sure if it's the Garmin, maybe my battery in the sensor itself - magnets are magnets I agree - no reason shouldn't work.:mad2:


I'm not familiar with your sensor, but keep in mind 

1- strength, magnets vary, but I've never found any that didn't work
2- distance, magnetic field stength falls off with distance, so stay as close as possible
3- polarity, While it doesn't matter which pole is toward the sensor, there's little on no field in between. Use a paper clip to find a pole, and that's what needs to pass the sensors hot spot.
4- track- the pole of the magnet is what should pass through the sensors hot spot, some sensors have a mark or marks to identify the hot spot.
5-speed, the magnet moves slower at the hub, keeping it in working range longer.

Lastly, something many people don't think about. the reed switch operates in a plane. If, for example, you have wide fork blades, and are angling the sensor inward to reach the magnet, the magnet will be pulling the reed switch sideways not in and out. Most instructions have a top view showing the sensor. You want to stay as close to that as possible. That's one more reason I mount closer to the hub where the spokes come to the blade, rather than having to swivel the sensor to reach.


----------



## vagabondcyclist (Apr 2, 2011)

Kontact said:


> Sigma computers use a much more powerful magnet, and won't work with others. So they aren't universal, but pretty much.
> 
> You can buy a rare earth magnet and epoxy it to a spoke, if need be.


I've been using a Cateye magnet with my Sigma. Couldn't really get the Sigma magnet to be stable on the spoke.


----------



## froze (Sep 15, 2002)

FBinNY said:


> A good and often forgotten point. There's a certain amount of time required by the reed switch to close and register the magnet's pass. If it goes by too fast it can pass without registering.
> 
> For that reason, you'll get better results with the sensor fairly low and the magnet closer to the hub where it's linear speed is lower.



Interesting thought, but I've never mounted mine low to the hub, in fact I mount mine about an inch from the nipple, never had a problem with registering speed even on a primitive 32 year old Paramount I once had, or on a couple of different wireless units, and now a wired again unit. I've registered speeds up to 58mph and not once had a failure to register read. Also no instructions I have ever read, including other computers friends had different from my own never mentioned that point. You sure about that?


----------



## MKO (Sep 19, 2011)

the pros glue their magnet onto the rim










bikeradar


----------



## calgary_jim (Jan 3, 2009)

I don't agree. My crank magnet is a different polarity than the wheel magnet and I can't find a replacement wheel magnet.


----------



## FBinNY (Jan 24, 2009)

calgary_jim said:


> I don't agree. My crank magnet is a different polarity than the wheel magnet and I can't find a replacement wheel magnet.


What don't you agree with, especially since this is an 20 month old thread?

In any case, polarity of the magnets is immaterial, since they activate a non-magnetic reed switch or sensor.


----------

