Help needed for Sigma Sport Computer setup

Having just replaced the battery in my Sigma Computer I have had to reset the wheel size. (sorry no model number on the computer)

I set MPH then had to input wheel size. I am using 700x23 tyres on Rigida wheels.

I tried online manual stating 2133 but this was way out. I tried measuring the diameter and x 3.142 again way out.

Tonight i measured a straight line rotation distance. This came out at 2105 not far out from the 1998 from the PI method.

I went out on a measured 10 mile ride and ended up doing 15.6 miles

Whats going on? At one point I clocked myself doing 55 mph. Computer is way out?

Anyone got any suggestions or had similar problem? I seem to be doing 1/3 more distance and speed than I am actually doing :evil:

Thanks

If you are using MpH as oppsed to KmH, you have to multiply the wheel circumference in mm by 1.61...........that may well explain why yer ten miles ended up as 15 or so.

Incidentally, once they're properly set-up, these sigmas are really accurate up to some pretty high speeds: I had one on my old motorbike which I used on the track a fair bit, and clocked it within 1mph accurate of my gps logging device at about 130mph. Anything faster than that and I'm looking at the track, not the speedo!

Aye- I came across a "how To" on a Bike site for fitting a bc1200 on a shooge rocket type thang.......
Only hassle I've ever had from sigma computers is the battery life of the wireless setups.........use them on all my bikes, the oldest from 1996 is still going strong.

Lysander":29l7njzt said:

If you are using MpH as oppsed to KmH, you have to multiply the wheel circumference in mm by 1.61...........that may well explain why yer ten miles ended up as 15 or so.

Click to expand...

If I multiply by 1.61 I get 2105x1.61=3368

Do you mean divide to give me 1307? This would make more sense.

Aye- yer right enuff........I just had a look at the instructions.........it says Ws= mm :1.61, so its divide

mehh..........it was much easier when everybody used cubits and furlongs, ye knew how fast yer chariot was going then........

Does anyone know how to change the battery in the Sensor on the BC 1200?

I presume I need to undo the tiny screws but these are very tight.

Thankyou

Nige.

http://www.sigmasport.com/en/service_ce ... kecomputer

http://www.sigmasport.com/en/service_ce ... kecomputer

Should let ye download the manuals- I use a jeweller's phillips screwdriver to unscrew them- I also discovered that if ye take out the battery from the handlbar receiver between rides (it's retained in clips to the battery cover), it really saves juice.

Thankyou very much, new batteries fitted and back on bike