# Serfas True 500 + Cateye Strada Wireless = Fail



## rccardude04 (May 17, 2009)

So, just wondering if anyone else had something like this happen.

I have been troubleshooting my Cateye Strada Wireless computer the last couple weeks because it intermittently didn't work. Could get almost 4 feet away without issues while testing, magnet reads fine, whatever. Go on a quick test ride, no problem. Go out on our normal night rides and WHAM, 0.0mph almost the whole time. 10-15 mile rides would show 1-2, sometimes 3 miles on my odometer.

What was the culprit? After exchanging for another Cateye and trying different sensor and computer locations, I realized the only thing different between testing and riding was my Serfas True 500 light. It seems to interfere with the Cateye's weak signal, especially on the lower settings. Something about the switching frequency of the dimming circuit in the light makes my Cateye freak out and just not work hardly at all. Seems to work OK with the light on 100% power, but that's not enough burn time for a full night ride. So, back to the Night Rider MiNewt 150 on the bars and I'll save the 500 for the helmet I guess. Not going to get as much use that way but what else can I do?

Maybe I just got a bad light?

Or maybe I should just sell it and get something different? Or is it common amongst high-powered lights to not get along well with wireless computers?

-Eric


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## gmcttr (Oct 7, 2006)

It's not that uncommon. My Cateye Micro Wireless has to be at least 8" away from my MJ-872 for it to work.


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## fightnut (Jul 5, 2007)

rccardude04 said:


> Or is it common amongst high-powered lights to not get along well with wireless computers?


Correct.


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## dirtydawgnz (Jun 5, 2008)

*noise*

There are 2 main types of circuits within most LED light. Linear and Switching.

Switching regulators produce electronic 'noise', this noise can be minimised by the designer if they arrange the circuit in a particular way. Most of the time it is not minimised and you get the situation you are experiencing - interference with other electronics.

A linear regulator does not produce 'noise'. It does however produce heat if the battery voltage is not matched with the output voltage (excess voltage is shed as heat).

Most companies use a switching regulator as it can be designed to suit most LED combinations and while using the one battery type. All this equals cheaper manufacture and therefore interference.


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## rccardude04 (May 17, 2009)

I'm sure there's a regulator to bring the battery voltage down so the LED doesn't draw too many amps, but I also assumed there was an FET switching circuit that manages the LED's on/off frequency similar to a fuel injector duty cycle in a modern car's engine to produce the actual dimming. It's interesting to see the projection of the light on a spinning tire because of the strobing effect of an LED bike light set to less than 100%. 

As for my other options, I guess I'll just leave the 500 as a helmet light. I was shopping around for lights but it sounds like anything with good power is going to have a similar issue. The local shop has a Light & Motion 600 in stock that was catching my eye but if it's likely to do the same thing I'll just stick with what I have. 

Thanks! Never thought it'd be an issue but it's a good thing to know for sure. 

-Eric


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## Buster Bluth (Sep 11, 2008)

You should see what these dang lights are doing to my pacemaker!


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## lou2uanme (Oct 11, 2009)

*High powered lights and wireless cycle computers*



rccardude04 said:


> So, just wondering if anyone else had something like this happen.
> 
> I have been troubleshooting my Cateye Strada Wireless computer the last couple weeks because it intermittently didn't work. Could get almost 4 feet away without issues while testing, magnet reads fine, whatever. Go on a quick test ride, no problem. Go out on our normal night rides and WHAM, 0.0mph almost the whole time. 10-15 mile rides would show 1-2, sometimes 3 miles on my odometer.
> 
> ...


The problem is not with the Serfas light. The problem is that the Cateye Strada Wireless is an analog sensor computer. You need to get a Digital sensor computer if you want to use a high powered light with a wireless cycle computer.

A digital wireless signal will not have a problem with the RF (radio frequency) interference that the high powered lights give off.

Check the data sheet for the Cateye Strata Wireless Computer for "Wireless Transmission" at the Cateye website.

You will see that it has an ANALOG sensor. You need to get a computer with a DIGITAL wireless sensor.


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## rccardude04 (May 17, 2009)

lou2uanme said:


> The problem is not with the Serfas light. The problem is that the Cateye Strada Wireless is an analog sensor computer. You need to get a Digital sensor computer if you want to use a high powered light with a wireless cycle computer.
> 
> A digital wireless signal will not have a problem with the RF (radio frequency) interference that the high powered lights give off.
> 
> ...


Not sure I understand what you mean by digital vs. analog? All the cateye wireless computers, I learned, use the same frequency for transmitting, which is apparently easily interfered with. Everything from high-powered transmitters to bike lights. I didn't think it would have anything to do with 'digital' or 'analog' but moreso to do with the extremely low transmission power and required high sensitivity of the receiver.

Could you explain the difference between digital and analog in this case?

-Eric


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## lou2uanme (Oct 11, 2009)

*Analog vs Digital wireless technology in cycle computers*

To give you an answer as to what is the difference between analog and digital wireless technology would take up a lot of space.

If you want a detailed answer do a search for "digital wireless technology vs analog"

The quick answer is that the analag wireless signal has very poor RF noise immunity, while digital wireless signal has a very high immunity to RF noise.

There are many wireless digital cycle computers available in the market, they are the more expensive ones. The analog cycle computers are the cheaper ones. Usually it is listed obviously on the packaging or on the data sheets at the company website.

I haven't checked all the Cateye computers but the Cateye Strada has an analog wireless signal and Cateye V3 has a Digital signal.


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## Cat-man-do (May 16, 2004)

...So, in keeping with the subject at hand; Can anyone recommend a good wireless bike computer that won't be effected by LED drivers? If you know of one that also has a "night light" function that too would be the icing on the cake. Hopefully I'm trying to keep it under $100. I'm setting up a new commuter bike and right now the pocketbook is taking some heavy hits with all the accessories I need.


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## string (Jan 13, 2004)

Try mounting your computers next to your shifter/ grip & place the light / battery on other side (I mount my light close to stem for centering).

I have had some success doing this with my strata wireless & a Dinotte 1200 light. It's not 100% effective but seems to provide enough distance to work 75% of the time (no idea why 75%... would have thought all or nothing).


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## rccardude04 (May 17, 2009)

lou2uanme: I should have looked around at the computers a little bit before asking you. I understand the basic difference between analog and digital technology, just not so much applied to wireless electronics. A quick 2 minutes on google has answered that question though. lol

It just seems like people tend to throw around digital vs. analog on a lot of topics and don't actually know what they're talking about. I'm sorry to admit I assumed you were throwing words around without any actual basis. So I apologize. 

I remember when radio-controlled hobby electronics went from the analog world to digital (AM/FM to so-called PCM). I never really knew how it works, but now it makes sense. Rapidly varying negative/positive shifts to spell out binary words corresponding to different values to be decoded by the receiver rather than a simple positive or negative shift from the central frequency (or amplitude). Makes sense now.  I do remember PCM technology having a LOT better interference tolerance, even to the point where if someone was on FM on the same channel, you could still drive your car. It was pretty cool!

Only makes sense that this would apply to bike computers. I guess the Strada wireless is a pretty basic unit. I didn't do much research before I bought the thing since it was just what the bike shop had. I may try to upgrade to one of the Garmin GPS-based units when the prices start to come down a bit and just live with this one for now. I've figured out how to make it work if I put the light on the bar between the brake lever and grip. It looks funny but it does work out at the right angle. Good enough for now! The Serfas is generally on my helmet while trail-riding anyway. It only goes on the bars while riding around town. And even then, my Nite Rider MiNewt 150 is enough. 

Thanks guys!

-Eric


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