Bike Computer mounting question

Post by **bimrluvr** » Wed Mar 08, 2006 6:06 pm

I have one of those bike computers that uses a magnet on wheel and a magnet sensing unit to give you speed, distance, trip, etc.

Somebody here recently mentioned having one and it got me thinking. Anyway, can anybody with one of these gizmos recommend the best way and location to attach the magnet and sending unit? Pix would help.

Post by **Boxer** » Wed Mar 08, 2006 7:43 pm

I have the pix here somewhere of Robbie's install. I'll find them by tomorrow if no one else gets it by then.

I want one of those. Where did you get yours?

Post by **bimrluvr** » Wed Mar 08, 2006 10:16 pm

Thanks Boxer.
I bought two at a local bicycle shop when I had our mountain bikes refurbed, and then I never mounted the 2nd on my wife's ride.
It's a nice way to address the inaccuracy of our speedo's. Once calibrated (which the user does) the speed is accurate to within 1% up to about 200 kph.

Post by **taosports** » Wed Mar 08, 2006 10:27 pm

A few links that may help :

http://mywebpages.comcast.net/billingsley/sigma.htm

http://www.canyonchasers.net/shop/generic/sigma.php

http://www.houseofthud.com/bikecomputer.html

Post by **bimrluvr** » Wed Mar 08, 2006 10:50 pm

Thank you, Michael. The links were just what I needed. I love this place.

Post by **taosports** » Wed Mar 08, 2006 11:03 pm

Glad to help.

One tip...make sure that when you do your roll out to calibrate the computer, your tire pressure is where it should be and you are sitting on the bike with what ever you plan to carry - all of this will have an effect on the guide number.

Boxerboy · Post by **Boxerboy** » Thu Mar 09, 2006 8:00 am

http://www.stephenbottcher.net/BMW/GS/0 ... SCF540.jpg

The magnet is superglued to the steel disc...for extra security.

Post by **rdsmith3** » Thu Mar 09, 2006 9:41 am

taosports wrote:Glad to help.

One tip...make sure that when you do your roll out to calibrate the computer, your tire pressure is where it should be and you are sitting on the bike with what ever you plan to carry - all of this will have an effect on the guide number.

Yes, this is good advice. What I do with my bicycles is to put a dab of grease on the tire, then ride in a straight line on my driveway for two revolutions. You could sit on your motorcycle and roll it with the engine off. I measure the distance from the first mark on the driveway to the last, then divide by two, then convert to centimeters (inches x 2.54).

Post by **CycleRob** » Fri Mar 10, 2006 12:24 am

Try these pics for a much more seccure installation:

http://r1150r.smugmug.com/photos/18789448-L.jpg
http://r1150r.smugmug.com/photos/18789447-L.jpg
http://r1150r.smugmug.com/photos/18789449-L.jpg
http://r1150r.smugmug.com/photos/18789450-L.jpg
http://r1150r.smugmug.com/photos/18789452-L.jpg

It has been trouble free for many years.
On the calibration method, I used 4 wheel rotations then divide by 4 for the rolling circumference starting point. I say starting point because for near perfect accuracy you'll need to utilize the very exacting divided highway mile markers to check and correct the error. Choose an interstate with lots of straight-a-ways and see if your indicated mile comes up short or long. Then stop and change the cal number by one digit and try again. You need to use the highway milemarker method because of tire growth and it's also eliminates any cumulative error (800 plus wheel turns per mile) you made in measuring. I was able to get an error of less than 5 feet per mile (5,280) in only 2 trys.

soggybottom · Post by **soggybottom** » Sat Mar 11, 2006 9:24 am

I use a light duty metric measure tape and measure the circumferance of the tire, this I beleive is most accurate, when I check with GPS they are very close, I do beleive the bike computer is more accurate, especialy in the odo. I use the Sigma Sport usually available on flebay for $25, I've read on some forum that this one works best and I'll confirm that, I've tried several. This is one of the most usefull cheapest mods you can do.

Post by **bimrluvr** » Sat Mar 11, 2006 3:37 pm

I was thinking along the same lines as Soggybottom, metric seamstress tape around the wheel while up on centerstand, and then on the ground with weight on to see how much it varies, if at all.

Post by **rdsmith3** » Mon Mar 13, 2006 1:09 pm

The tire is not compressed when you measure its circumference with a tape measure. That would affect your measurement.

I have not done this on a motorcycle. I just know from bicycle experience that measuring the length of the roll-out, with your weight on the bike, gives very accurate results.