Sigma Speedo for RT Help

[Mr. Frank]

I'm installing a Sigma bicycle speedo on my R1150RT. Does anyone have an accurate circumference for the Metzeler Z6 120/70X17 front tire?

[GCD]

I've installed these on two of my bikes so far. The easiest way I've found is to mark the bottom of the tire and the floor next to it, roll the bike forward until the mark is at the bottom again, mark the floor and use a tape measure to get the distance. Also, I purchased a package of very small "rare earth magnets" from radio shack, and glued the magnet to the brake rotor in a good place to go by the pickup coil.

 

Greg

Evergreen, CO

 

'00 1100RT

'73 R75/5

[Mr. Frank]

I've installed these on two of my bikes so far. The easiest way I've found is to mark the bottom of the tire and the floor next to it, roll the bike forward until the mark is at the bottom again, mark the floor and use a tape measure to get the distance. Also, I purchased a package of very small "rare earth magnets" from radio shack, and glued the magnet to the brake rotor in a good place to go by the pickup coil.

 

Greg

Evergreen, CO

 

'00 1100RT

'73 R75/5

 

Thanks for the reply, Greg. I used the paint dot method which seemed to work well. You are right on about the little magnets. Someone else tipped me off about that.

 

What I'm stuck on now is figuring how to attach Velcro to the back of the unit which is concave. I'll want that surface to be flat to mesh with the dash.. Any ideas?

[GCD]

Sorry, no help from me there...I mounted mine on the right handelbar next to the switch housing.

 

Greg

[mrsoup]

I used the brackets made to secure conduit/plumbing pipe to mount my Sigma. They come in various sizes so you can find one to match the shape of the back, made of steel or plastic. Trim to fit and secure with Super Lock velcro type material (Radio Shack).

[Mr. Frank]

I used the brackets made to secure conduit/plumbing pipe to mount my Sigma. They come in various sizes so you can find one to match the shape of the back, made of steel or plastic. Trim to fit and secure with Super Lock velcro type material (Radio Shack).

 

Thanks! That's a very creative solution. It allowed me to attach the bracket to one of the dash screws.

[Tschamp]

Curious, why would you put a bicycle speedo on your motorcycle?

[Mr. Frank]

Because I have a BMW speedometer, it is not accurate. If you want to go exactly 5 or 9 mph over the posted limit, you have to know your exact speed. Many people use a GPS for that purpose.

[Vincent]

I'm not sure of the circumference, but I key the setting of 1169 for this tire (Metzeler ME-Z6), on my sigma. (I have the circumference somewhere, would have to search). I've been using a sigma for about 5 years now, love it. And more on the question of why; the sigma is accurate to over 150 mph, it gives average speed, ride time, maximum speed, and gives a 2nd odometer. It's a great trip computer and I would not like riding without it. I use a rare earth magnet from radio shack on my front brake rotor.

[Mr. Frank]

Using the paint dot method I came up with 1144, a 2% difference from you. The speedometer error seems to be what I've determined pacing friends with GPS's.

[rdsmith3]

I'm installing a Sigma bicycle speedo on my R1150RT. Does anyone have an accurate circumference for the Metzeler Z6 120/70X17 front tire?

 

On my bicycle, I use the roll out method. It is very accurate. Put a dab of grease or paint on the front tire. Sit on the bike. Roll your bike in a straight line until you have completed two full rotations. Use a tape measure to determine the distance from the beginning mark to the last (third) mark, then divide by two. Convert to mm.

[Vincent]

Mr Frank, I found my original notes, 1169 is for a Metzeler ME-Z4, my bad on post above. I guess I need to re-measure for the ME-Z6. You should find a 4mph error at low speed, and at highway speeds up to 6mph error. Good riding!