wheres the most accurate position to place the magnet on the spokes. i have a 26 inch rim and no body to drive along side of me to tune it.

No matter where you put the magnet, it will pass by the sensor once per revolution. That said, at higher speeds, the magnet will be passing the sensor faster, so you may want to position it closer to the hub, because if it's out by the rim it may pass the sensor too fast for it to be registered.

Then again I've seen people using cyclocomputers near the middle of the wheel on their motorcycles with no problems, so the advantages in placement are possibly academic.

Based on photos I've seen, the correct place for a speedo is up the crack of your butt.

Sorry, I couldn't resist. I've had a bad day at work.

Man, I thought you were talking bathing suits for a minute

I don't think the position of the magnet matters too much as long as it passes close enough to the sensor to be picked up and trigger an electrical impulse. The tuning of the speedometer (at least the ones I'm familiar with) is setting up the wheel diameter in the computer.

hahaha...you need a 6 pack or a bottle of wine

I don't know that it makes a difference. If anything having it further out on the rim will have the magnet go by faster which probably would improve the pick-up (faster motion ==> faster change in magnetic field ==> stronger induced current). "Speedo" reminds me of a funny commuting story. One day I'm three blocks from work getting an apple turnover at the local Italian deli run by a Korean guy named Lee. The large Italian woman who runs the checkout sees me and says "Lee! You see what that guy's wearing? THAT's a Speedo!". No joke. To her, bike shorts == "Speedo". What's funny to me also is that "Speedo" == a certain type of bathing suit in the US when it's no more than a brand name. Anyhow, if you're wondering, I'm now recognized as a regular at the deli and they don't mind if I roll my folder in there (time saver! don't have to fold).

I've found putting a rare earth magnet (strong little things) on the spoke magnet your computer tends to pick up better.

I've hit just shy of 50mph on my road bike and I have the magnet about 2" in from the edge of the rim on my road bikes. I've never had a problem with it picking up the magnet as it sweeps past.

BTW-I actually have a speedo bathing suit. I wear it under my wetsuit when surfing so that I don't have to worry about my junk popping out when I strip off my wetsuit at the car.

There really is no "accurate" position that is better than another. The magnet only tells the computer when the wheel has revolved and then the computer multiplies that by the wheel size you entered during the setup to calculate MPH and distance.

yeah i feel you on the brand name topic but they do make nice suits for competitions...i was on swim team throughout highschool and 1st year of college.

the correct spot for a speedo is left in the store, never to be bought.

I have speedo swim gear.... it's a nice pair of trunks. It's just a brand. They make lots of other things.


i keep my magnet as close to the hub as I can get, but it really shouldn't matter.

whats the animosity towards speedo. if your smart you goto marshall/tj maxx and get it dirt cheap.

It can if you have a dynamo hub. Both the Schmidt and Shimano have been known to interfere with the magnet pickups. I've not had issue with my Shimano hubs but I keep my magnet 3/4's of the way to the rim.

Seriously, having the magnet closer to the rim produces a stronger "spike" and or pulse which is what needs to go through the wiores. It's shorter, but stronger. Shorter doesn't matter. Stronger does.

All of mine have used reed switches. Sometimes you can hear the contacts close when you move a magnet to the sensor.
As there is no current induced it can't get stronger when moving the magnet faster.

QFT. If it used induction, it would have trouble picking up slow speeds.

Honestly, I installed my magnet pretty much halfway on my commuter hybrid. This is where I've seen it installed on almost every bike I've seen, so that's why I put it there.

When I bought my new road bike and a rack, computer, headlight, and seat bag, the shop manager just grabbed everything and tossed it on for me. The computer's magnet ended up being pretty much in the middle of the spoke.

There's one guy I ride with on Monday nights, whose computer has a single "brick" that goes over the non-drive side chainstay. It has a sensor on the inside for the rear wheel and the outside for crank cadence. On his bike, the magnet is about 2-3 inches from the rim. He's never had a problem, either.

I have mine as close to the hub as possible, I want the wheel to be as balanced as possible and having a magnet right near the rim isn't going to help.

What computer do you use that has a reed switch?

I thought by now someone would have posted a pic of a speedo worn correctly!
I shan't be the first