Wireless computer and canti interference?
 

Hi all,

My wife bought me a Knog Nerd 12 function wireless computer for my birthday. I ride a Surly Crosscheck, so have canti studs on my fork.

I can't seem to get the computer and sensor attached to my bike in a way where the computer picks up the sensor. The only place that worked was having the sensor on the back of the fork and the computer at the junction between the downtube and headtube, a less than ideal location.

Is the problem that the canti studs are interfering with the signal? Has anyone else had this problem?

Thanks!

-Chris

Cannot be . it's a radio frequency transmitter-receiver set not a laser beam.

Have to get the spoke magnet to pass very closely to the sender on the fork.

Will having the spoke magnet close to the sensor increase the signal strength? If I hold the computer closer to the sensor, then it does pick up the signal.

I would replace the battery as it should pick up the signal a lot further away than that. Most wireless computers want the sensor to be within about 24 inches as per instructions. I have seen some rechargeable light systems or heart rate monitors that can interfere as well, but I have not worked with this brand of computer before, but the basics are the same. You will also find that in some cases other electrical things(building alarms or transformers) might interfere with the computer as it is on the lowest rung of the power scale. But for the most part they look clean on the bike and work as well as most wired computers..

I'm going to disagree with the other posters. I've installed a good number of wireless computers and have noticed significant differences in reception vs. head location. I don't claim to be an electronics expert, but it looks to me like a clear line-of-sight helps. I own a couple of recumbents both of which "stretch" the advertised range of their wireless computers. (31" for my single recumbent, 33" for my tandem) In both cases, mounting the pick up on the side opposite the chain made the difference between working and not working.

My regular practice is to install the wheel magnet and sensor first. Then I spin the wheel and hold the head close to the sensor to be sure that I get a MPH reading. Finally I hold the head in various locations on the handlebar and stem to see where I continue to get a signal.

I have installed wireless computers that came with a sheet showing how the location effected the operation. It had to be line of sight and fairly close. Just having the bars in the way was a problem. The location diagram confirmed this. It is a very weak signal, that's why it has problems. I agree about replacing the batteries in the sending unit and the computer head. Weak batteries in the head can have trouble picking up a signal as well as the sending unit batteries.

Retro grouch is right. Most computers send out a narrow cone shaped beam vs. transmitting 360°. This serves two purposes, first it lower the power requirements extending battery life. Second it reduces cross talk or interference when two owners of the same computer ride together.

There are a few steps to getting a good connection.

1- try for line of sight, yes it's radio and not light, but metal obstacles interfere. If you have canti's and a short stem, mounting the sensor lower may help.
2- note the correct orientation for the sender, some only transmit in one direction, so there's a top and bottom, and you might have to switch sides on the fork.
3- know how the reed switch works. Some are single ended so work best with the magnet passing low on the sensor. Others like SigmaSport are teeter/totters and work with the magnet passing above or below, but not at the center.
4- make sure magnet distance is short, about 1/8" or less.

Lastly when setting up and testing, be aware that some sensors and computers have a sleep mode to save batteries. For example a SigmaSport computer won't begin receiving until a bump or vibration wakes it up and turns on the radio. This used to drive machanics crazy when they couldn't get them to work on a repair stand. If your's won't receive, bounce the front wheel, or in a stand give it a good shot.

Reading all of this makes me more certain than ever that wired cyclometers are THE way to go. There is only one battery, the head location is only limited by the length of the wire and no crosstalk or RF interference with anything. To say nothing about the fact they cost less.

For the majority of cyclists and applications, wired computers do make a lot of sense.

Let me see if I understand. Half the price, twice the reliability. Sorry, no one will ever go for thatl.

Thanks all for the advice.

Strangely the signal is stronger with the sensor mounted the wrong way. There are arrows indicating which way should be up, but it works better the opposite way. Weird.