I've been doubting the accuracy of my speedometer, so I added a Sigma Sport bicycle computer:

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It mounts to the handlebars using an included O-ring, which is used like a rubber band: http://gs500.specialgreen.com/img/cyclocomputer/side.jpg.

The included magnet is made to attach to a bicycle spoke, so I followed others' advice, threw away the included magnet, and bought a $2 pair of "rare earth magnets" at Radio Shack instead.  Most people seem to mount the pickup near the brake, and put the magnet on the rotor.  But I was a little nervous about the magnet maybe getting stuck in the brake pad housing and somehow interfering with braking.  Also, I noticed that the spedometer cable running down to the left side of the wheel provided a good path to run the cable for the new spedometer.  So I epoxied the magnets to the plastic bearing cover on the left side instead:  

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The pickup sensor/sending unit attached to the fork using the kit's own mounting hardware.

The built-in wire was not long-enough to reach from the fork to the handlebar, so I spliced-in some extra wire.  I soldered mine, but I'd recommend getting some 3M ScotchLok crimp connectors from Radio Shack or a hardware store instead (http://www.skyvision.com/store/mi2500061.html), which woud be faster, easier and more reliable.

About 1/3 of local bicycle shops sell the Sigma Sport cyclocomputers; my local REI sells 4 different models from Sigma Sport (http://www.rei.com/online/store/Search?textQuery=sigma), which was a better selection than any of the bike shops, and about 30% cheaper.

I haven't had time to calibrate it well yet, but it's useful already having the clock, stopwatch and an extra trip odometer.  Too bad there's no backlight; it would be really cool if the spinning magnet could generate enough power to drive a phosphorescent backlight!

Quote from: Rema1000Too bad there's no backlight; it would be really cool if the spinning magnet could generate enough power to drive a phosphorescent backlight!

Nice.  Is that the BC1200?

Why is it that so few bike computers have backlights???  I've been wanting to get one for the speedo and clock, but I really want to be able to see it at night.  Sigma makes a little light attachment, but I don't know how well it works/looks.

Anyone know of any other cyclocomputers that will handle motorcycle speeds?

I know you said you haven't had the chance to calibrate the bike computer yet, but what are the initial results?  How far off does your GS speedometer appear to be?

Yes, it's the BC1200.  The 1600 has cadence, which I didn't want .  The two cheaper models seemed to have a smaller screen with differently-shaped numbers.  There was an older model called the "Targa" which was metal and had big numbers on the screen, if you can find a deal on it.  I looked at a Specialized cyclocomputer, and the salesman thought that it would register up to 99mph, but there was no way to test this without buying one.  I think Sigma Sport is the only manufacturer who deliberately markets to the motorcycle/go-kart/hobbyist.

I measured the wheel circumfirence with the front wheel off the ground, and programmed the cyclocomputer from that.  Now, I find no difference between the analog speedo reading and the Sigma Sport digital reading up until about 45mph.  Above 45mph, there is about 1mph difference, and 2mph difference at around 72mph (analog speedo 2mph too high).

Frankly, I'd been hoping to find a bigger difference, since I had been wanting to ride a little faster :mrgreen: .  I'm still hoping that the analog speedo is reading low, but I'm not as confident about it now.

I know what you mean. I was all happy riding around thinking I had a 10% buffer. Recently, GSJack tested the newer model GS with those radar signs that displays your speed and he said the new speedo is much more acurate I have to slow down :x

My 95 is about 10% off, father has a concours with the bike computer and his is also 10% off, fast. So we just go by the bike speedo. 85 is about 72-73mph and with a 70mph limit is usually what we ride on the interstate here..

GS revs around 8-9k at those speeds tho..eats the oil up.

whats the top out limit on these speedo's? most ive seen only go to 85mph.  the BC1200 goes to what?

Strangely, the Sigma Sport manual and web site don't say a thing about this.

I haven't had it above mid-70s, but many web pages state that either all Sigma Sports, or just the 800 and higher, go to 183mph (do a websearch on "Sigma Sport" AND "183").  I have also found some 2003 catalog pages stating that the Targa and BC1400 had 183mph top speed, but no mention of top speed for the other models.  So perhaps 183mph is the top speed for a couple models in 2003 and all models in 2004.

I have seen the high 90's on my SigmaSport BC400.

hey jasonB,
you said "So we just go by the bike speedo. 85 is about 72-73mph and with a 70mph limit is usually what we ride on the interstate here..

GS revs around 8-9k at those speeds tho..eats the oil up."

When your speedo reads 85 your doing 8-9k rpm? That seems high, mines doing around 7k reading 85 mph.
93' GS
-ash

With my 15 tooth front sprocket, an indicated 90MPH is right on 8000RPM.

If I remember righ 8k is 80mph but I'd have to go out and ride to be sure. I also have a 150/60 rear tire on my bike with the stock size 110/70 front.