View Full Version : cyclocomputers and magnets out there!

05-30-2006, 12:53 PM
Does anyone else experience this (and do you have a solution/recommendation)?

I have a basic, Nashbar brand wireless cyclocomputer. It records speed, time, average speed, max speed, and distance, and then has an odometer. It uses a magnet on the front wheel to track it's info (pretty standard, I think), and I've got it calibrated (checked by riding with others for comparison).

I am VERY frustrated, however, by how magnetic fields out there in the world constantly mess with it, and screw up my data! I work at big hospital complex with Lord knows what for radiation and magnetics. And I regularly ride through technology central (aka. Kendall Square at MIT) which also messes it up. And by "messes with it" I mean: I'll be at standing at a stop light going 75mph! As you can imagine, it messes with average speed and distance and time. It even does this if I hold it near a computer.

HELP! Is this normal, or is it just my cheap device?


05-30-2006, 01:00 PM
I suspect it's not the magnet, but the RF signal between the wheel sensor and the computer. I've not heard of such problems with wired computers, even in Kendall Sq. Wireless units seem much more susceptible to interference. There was a thread several months ago discussing wireless computer problems.

05-30-2006, 01:15 PM
That sounds totally frustrating.

Have you talked with other cyclists who are riding through the same areas? I remember seeing a bicycle parking area at MGH (I didn't make that up, did I?) - can you talk to some of the other riders at the hospital to see if anyone else is having the same problem?

It also might be worth trying a step up from your inexpensive Nashbar device. I've been using a Cateye wireless computer and I've been happy with it. I just checked online, and the model is the Cateye Wireless CC-MC100W. It has the same functions you mentioned, nothing fancy. I picked mine up at REI, but I imagine you can find them at a local bike shop too.

--- Denise

05-31-2006, 07:37 AM
I used to use a Cat-Eye wireless, but I had too many problems with it not picking up or going haywire so I switched to a wired Sigma Sport.

The problem you get at stop lights is from the induction loop sensor that is used to change the light. Wired systems aren't affected by them. My heart rate monitor is affected by some things too - invisible dog fences most notably.

05-31-2006, 09:40 AM
Thanks for the suggestions and insight...more reason for me to race to those green lights so I'm not stuck at them! Yes, Denise, there is a bike cage at MGH but surprisingly I rarely run into other bikers when I'm in there, and when I do not everyone appears to be equipped with 'puters. But I'll take a closer look!

I'll also take a look at the sales on new computers recommended.


08-25-2008, 06:17 PM
A bit late on this but I've been away from the forum for a while...but I've got a Nashbar wireless and I've noticed some wacky max speed readings as well. Everything else seems to work just fine, but I'd get to the end of a 3 hour ride and my max speed was between 60 and 74 mph - HA!! I'm trying to find a good computer with cadence - was thinking I wanted wireless but after reading about all the problems, wired is fine as long as it works.

I also noticed the Nashbar would go nuts if I got it near my wireless laptop, ruining my data until I figured out that I need to step AWAY from the laptop when I'm inputting the data. I think this is just a problem inherent in less expensive wireless computers (I got mine in a package deal with a Polar HRM watch - LOVE the HRM, not so much the computer).

I just got a Blackburn Delphi 2.0 for my *NEW* Specialized Rockhopper; I thought it had wired cadence (misread the package and didn't research it - my fault), but it doesn't so I'm returning it after reading bad reviews and discovering the lack of a cadence feature (and, apparently, no way to upgrade and add the cadence sensor). I've read that the Sigma BC1606L is pretty good, so I think I'll order it and see what happens. I'm not a racer by any means, but I am doing the 65 mile LIVESTRONG ride in October and would like to be able to train well so I can finish it without dying.

Just my $.02. :D

08-26-2008, 03:09 AM
Unfortunately, this is a problem with wireless computers. It seems to be most prevelant in cheaper ones, or those that use analog wireless signals. However, my $100+ digital VDO still succumbs to this occasionally, mostly because of high-voltage power lines, not so much with induction loops, HRMs, invisible fences, etc.

Going to a digital wireless computer will help, but probably won't alleviate the problem in all situations.