ready for my first 'cycle computer' ride!

So I spent part of the evening installing my wired MEC cycle computer on my 29’er. I am anticipating my first commute to work on it tomorrow, that is if the torrential rains abate a little as promised.

I chose a wired computer as I felt it would give me options in terms of mounting positions given that apparently the wireless can be a bit finickedy when it comes to picking up the signal. For the time being I just have the computer mounted about midway along the seat post tube but eventually I hope to have a touring handle for my Big Apple Bedford 29’er and if all goes well I may have a spot to mount the computer where I can acutally read it while riding. In the meantime it will be fun to see what my average speeds and top speeds are as well as get a sense of distance travelled.

The only thing I am wondering is why I hear a faint sound every time the spoke magnet passes the sensor on the fork. The two parts are the required 2 mm apart and are not touching but still can hear a slight sound as they pass each other. Anyone else notice this on their set up? Any idea what it is?

Well the test run will be interesing, I’m looking forward to riding my newly wired uni!

Does it sound like a muffled click? Both my setups do it, and it shouldn’t be anything to worry about. I don’t know the exact science behind it, but the sensor is basically a magnetic switch, and it records an event every time the magnet on your spoke passes by close enough to trip the switch. All the data is then calculated out by the number of times the switch is tripped, multiplied by the info you entered on your wheel circumference. This is why if you have your magnet positioned incorrectly, the act of idling can drive your Top Speed through the roof.

As long as the noise you hear is not from the magnet hitting the sensor, I’d say ignore it.

Thanks Tom, I think you described the sound exactly and explained what is happening clearly, thanks!

Also I have the sensor and magnet mounted about midway up the frame as that’s where there is appropriate space to have them pass accurately. I take it by your explanation that it doesn’t matter so much how close or far from the hub the parts are located as long as one passes the other reliably so that the revolutions of the wheel can be noted, is that correct?

Ok, still dark out but not raining so I’m about to the hit the road. Here’s hoping all the bits stay where they are supposed to and I arrive at work/school with some ride data. :smiley:

they are 2mm apart when you are not riding it and flexing it. that noise is the two pieces making contact

twist the ‘fork part’ around so it is not so close to the spokes (or slide it a little up the fork (as well as the spoke magnet)

there can be a pretty large space between the two pieces and it still register fine.

I dunno Brian, it made that sound even when I was spinning the wheel while holding the uni off the ground…and I could see that the sensor and magnet were clearing each other fine. I think its more like what Tom was talking about.

Anyways, I’m back in now from a great ride to work in the clear morning light and a windy, stormy ride home. Still it was all worthwhile given the ride data that I was able to collect. What fun! I’m liking the average speed, top speed and distance travelled options. Some day it will be cool to actually see my current speed while riding but that’s going to be a part of another project.

Tom gave you an accurate description of the operation of the magnet/switch unit. Everyone knows that Brian is a lunatic and can’t be trusted. I think he lies occassionally just to annoy people. He’s a Canadian; what do you expect? Oh…sorry. He’s from ONTARIO; what do you expect? There, that’s better.

Greg, did you forget to take your senility pills again?

Glad you clarified that Greg. :smiley:

And the resulting data was???:smiley:


ok, so its early in the season for me…


it was a hilly route…

average speed 15 kmph

total distance 17 km

that’s it for today…

stay tuned…

… bound to get faster and longer as the year continues. :wink:

Correct. Optimize for the right distance between sensor and magnet. Whether they are both close to the hub or closer to the rim doesn’t matter, because the wheel still makes the same number of revolutions regardless, and that’s all the sensor cares about.

thanks Tom. :slight_smile: