Why is my speedo moving when I'm not on my bike??

Anonymous

Hi.

Well today whilst I was in class I've travelled an extra 32 miles and averaged 33mph, just by sitting here!!!.

Anyway to stop this happening to my current speedo I cant afford a new one!, when its near my mobile phone and I turn it on it happens and a guy in my class put it near his iPod and when he was pressing buttons or scrolling it made the speedo start moving? Messed up my speedo and had to guess how long I travelled today to put on cycling log , about 11.1 miles in 40 mins I think but I cant remember due to the speedo moving by itself!!.

schilbach

I get this at home as well - when I'm trying to input data into my laptop - thought it might be the wireless or something!

Gussio

Unless you have suspension forks, then a non-wireless computer might be the best choice to avoid this problem.

el_presidente

or alternatively some sort of faraday cage

Barrie_G

el_presidente wrote:

or alternatively some sort of faraday cage

Which still isn't going to be much use to a wireless unit as it would block out the signal from the sender :roll:

el_presidente

Barrie_G wrote:

el_presidente wrote:

or alternatively some sort of faraday cage

Which still isn't going to be much use to a wireless unit as it would block out the signal from the sender :roll:

well take it out of the cage when you put it on the bike DUURRR

whyamihere

Barrie_G wrote:

el_presidente wrote:

or alternatively some sort of faraday cage

Which still isn't going to be much use to a wireless unit as it would block out the signal from the sender :roll:

You could extend the cage to cover the transmitter. Then again, there may be a cadence meter, so the cage would need to cover basically the whole bike, and the rider too if there's an HRM. The added weight would probably require some extra kind of propulsion, and in order to keep the whole thing stable, an extra wheel would be necessary. On the upside, lighting systems could be integrated into the cage, and larger batteries could be easily carried.

In fact, there's been a prototype already built, link here.

geoff_ss

All 'wireless' devices use a carrier frequency of 2.4ghz. When it's used for sophisticated things like the latest model RC transmitters they search for an unused channel to avoid cross talk (disastrous for a flying model). Simple, very short range devices like wireless cycle computers are probably open to everything in the spectrum, which will include wireless internet connections, with unknown effects.

A way of preventing problems might be to keep your computer read-out unit in a metal tobacco tin, for example, as sort of Faraday cage, when not fitted to to the bike. Just a thought - are metal tobacco tins still available? I have a loads inherited from my father - very useful for all sorts of things

Geoff

redvee

No 'baccy tin? Try an empty foil crisp packet. Much better to empty a crisp packet than to empty a 'baccy tin

johnno_uk

Geoff,
many of the new wireless transmitters are coded, so the Receiver / Transmitter pair have a unique code, making it much harder for interference to be seen or interpreted as spurious data. i.e. the transmitter sends data plus an address/identifier code , usually separately, and if the receiver sees some data but no address code within a window, it ignores it . The sensitivity is also much better on the receivers of the latest ISM band chips that are inside these kind of parts, and also the co-existence with other 2.4GHz like wifi is also much better making them much more robust. Should have stuck with the 868MHz EU ISM band perhaps , but thats no good if you want to sell worldwide.

I used to have this problem with the first VDO wireless computer i brought from the shop - and it would lose data and also pick up spurious data. It was uncoded. I took it back and swapped for another one that was coded - happy bunny ever since. Many of the shops have mixed coded / uncoded stock and its not always printed, so you have to look on the manufacturer web site at the model and revision dates etc.. a right pain.

WILLHUB, take it back to the shop where you bought it - explain the problem, if its a reputable shop they will swap it assuming thats where you got it from.