I have 2 PK Looptails, one has a small piece of rubber in between the 'seatstays' just behind the seatpost tube, not sure if my terminology is correct there, but anyway i'm sure you know what i mean
.......the other hasn't got this piece of rubber....
What was the rubber for? Was it just part of the manufacturing process? Did they all originally have em?
Does yours???
Interesting eh !