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PostPosted: Wed Apr 21, 2010 8:08 pm 
Dirt Disciple
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Joined: Sat Feb 20, 2010 5:55 pm
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Location: Black Country
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


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PostPosted: Thu Apr 22, 2010 10:41 am 
Retrobike's #1 Comedy Genius
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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.


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PostPosted: Thu Apr 22, 2010 11:04 am 
Dirt Disciple

Joined: Sat Apr 03, 2010 7:11 pm
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Location: manchester/stockport
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!


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PostPosted: Thu Apr 22, 2010 11:43 am 
Retrobike's #1 Comedy Genius
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Aye- I came across a "how To" on a Bike site for fitting a bc1200 on a shooge rocket type thang....... :P
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. 8)


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PostPosted: Thu Apr 22, 2010 12:46 pm 
Dirt Disciple
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Location: Black Country
Lysander wrote:
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.


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

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


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PostPosted: Thu Apr 22, 2010 1:05 pm 
Retrobike's #1 Comedy Genius
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Aye- yer right enuff........I just had a look at the instructions.........it says Ws= mm :1.61, so its divide :oops:

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


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PostPosted: Wed Jun 30, 2010 10:46 pm 
Devout Dirtbag
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Joined: Tue Jun 29, 2010 11:10 pm
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Location: Lincs
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.


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PostPosted: Thu Jul 01, 2010 8:11 am 
Retrobike's #1 Comedy Genius
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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.


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PostPosted: Thu Jul 01, 2010 5:47 pm 
Devout Dirtbag
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Location: Lincs
Thankyou very much, new batteries fitted and back on bike 8)


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