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Misplaced priorities?
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Discussion Starter · #1 ·
I have a no-frills Cateye Velo 2 computer on my bike. One of the clips that holds the magnet on the spoke has broken, so the magnet likes to slip off the spoke at high speeds & flap loosely. Thus, I can't get a reading on the computer. I've tried taping the magnet onto the spokes, but the tape won't hold. It seems that a new magnet is in order, so my question is: Will I have to get the same "between spoke" style of magnet, or would a "single spoke" style magnet (a la some of Cateye's other models like the Enduro & Mity) work with my Velo 2?
 

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Any magnet will do. The sensor is just a normally open magnetic reed switch that closes when the magnet flies by. As long as the magnet is strong enough, and all that I have tried are, it will work. I use the magnets that screw on to a single spoke on my wire-spoked wheels. The magnet on the wheels in my avatar was intended to be used on a crank for a cadence sensor.

Jim
 

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kpcw said:
The micro needs to know the size of you wheel etc and the sensor and magnet need to be positioned per the instructions (placement away from the hub = x inches etc).
It makes no difference where on the spoke the magnet is positioned as long as it passes close enough to the sensor.
 

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JimP said:
Any magnet will do. The sensor is just a normally open magnetic reed switch that closes when the magnet flies by. As long as the magnet is strong enough, and all that I have tried are, it will work. I use the magnets that screw on to a single spoke on my wire-spoked wheels. The magnet on the wheels in my avatar was intended to be used on a crank for a cadence sensor.

Jim
Never heard of an open magnetic reed switch.
A lot of magnetic sensing use the Hall-effect principle to sense
the proximity of a magnet for an electronic switching action to occur.
 

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Come on, think about it for a second

kpcw said:
The micro needs to know the size of you wheel etc and the sensor and magnet need to be positioned per the instructions (placement away from the hub = x inches etc).
The sensor measures angular velocity (revolutions/radians per unit time), then the computer multiplies it by the outer tire circumference that is programmed into it to get distance, current speed, etc. The magnet can be located anywhere on the wheel.
 

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kpcw said:
My thrust in putting the sensor x inches from hub on the fork...is cause if you read the directions, they tell ya that...so (the obvious) the sensor is close enough to the magnet etc.

Speed=D/T :)
I have 5 bike computers, none have such directions, and the sensors are not mounted on the forks.
 

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Misplaced priorities?
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Discussion Starter · #7 ·
I appreciate everyone's help. I'll just waddle on over to the LBS later today and see if we can reach a deal on just a magnet (they'll probably try to sell me a whole new unit, but they wouldn't be proper salespeople if they didn't). All the directions that I've seen (all Cateyes) only ask that you input the wheel size and leave no more than 5 mm of space between the magnet & the sensor. Perhaps some other brands' directions do tell you to place the sensor x inches away from the hub to ensure the proper proximity between the magnet & sensor. Cheers!
 

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As you are looking for replacements, check out the Sigma product if you run across it. As long as you're not using bladed spokes, it's the slickest one that I've seen.

Not that it really matters - a refridgerator magnet and a dab of hot-glue would do the trick if you could get it positioned.

Trivial info regarding magnetic reed switches vs. hall effect generators: both are used in cyclometers. Reeds are usually a bit less expensive, though not necessarily less reliable. Reeds tend get used more in wireless sensors for energy budget reasons. If you spin a wheel, reed switches make a very faint 'tink', 'tink' noise as the magnet passes, while hall generators are solid-state and silent. Of course, just because you can't hear a reed doesn't mean it's not there.
 

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Misplaced priorities?
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Discussion Starter · #10 ·
danl1 said:
Not that it really matters - a refridgerator magnet and a dab of hot-glue would do the trick if you could get it positioned.

Trivial info regarding magnetic reed switches vs. hall effect generators: both are used in cyclometers. Reeds are usually a bit less expensive, though not necessarily less reliable. Reeds tend get used more in wireless sensors for energy budget reasons. If you spin a wheel, reed switches make a very faint 'tink', 'tink' noise as the magnet passes, while hall generators are solid-state and silent. Of course, just because you can't hear a reed doesn't mean it's not there.
Well, I transferred the magnet from my MTB to my road bike & picked up a new magnet at the LBS for my MTB. Given what they charged me for the magnet (5 frickin' dollars), I should've considered gluing a refrigerator magnet onto my spoke. I try to support my LBS as best I can, but sometimes, their prices aren't even close to reasonable. :mad:

Yes, I heard the 'tink, tink' noise when I was messing with the positioning of my new magnet.

Problem solved. Thanks for everyone's help! :cool:
 
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