We had a similar issue...Speedster CoPilot and we damaged the wire twice (replaced once) when transporting. We then switched to the Cateye Double Wireless which we are happy with. The stoker didn't really want/need the cadence feature, but because of it the sensor is mounted on the chainstay, allowing the distance to the unit be sufficiently small to read consistently. Minor issues is the sensor on the chain stay sometimes gets pushed out of alignment (its zip tied in place) when transporting....but a little nudge by hand is all it takes to correct it. I just replaced the battery on the sensor last week, after 2-3 years of use and about 3,000 miles. Not great, but it takes a cheap and easy to find 2032 battery. The only demerit I give the Cateye are the instructions for set up and syncing the sensor. Cryptic. http://www2.cateye.com/uk/product_detail/556