If you have inverted forks (and you should) it will not do this. Rayder.. a Sigma is a little bicycle computer you can put on your bike to use as a speedo if you've changed gearing on your bike (bikes without the front wheel speedo cable). It measures top speed, distance, average speed etc. Love mine.
i don't have an add on speedo on the gixxer, but I thought I would my $.02
I have had several bicycles with speedos. The wires always got in the way. Eventualy I changed my mounting methods. I use to use zip ties. But the suck at holding the small gage wires. I use clear electrical tape to run the wires. I route the wire up the fork, across the brake cable, and to the bars. Then I run the clear electrical tape over the wire. I run the tape with the wire. At the ends I use electical ties to prevent the tape from coming lose and peeling back. And the ties work as a back up incase the tape comes lose. With the tape, you can usualy position the wires so they dont hit anything.