Fork abrasion clip, what does it do?

[SteveM]

I just noticed a thin plastic ring dangling from the left fork on my Triumph Rocket III Touring. The parts if he calls it an abrasion clip.

What does it do and how critical is it to replace it. It’s a $4 part but there appears to be considerable disassembly to put it in.

[SteveM]

I'm adding some additional information to help sort this out. There are 3 pictures:

1. The diagram from an online parts vendor showing part #18 circled in red, which I believe is what fell out.
2. The part description and part number from the same vendor.
3. The disassembly diagrams from my service manual which does not show this part at all.

My belief at this point is that the part is not part of the fork mechanicals, thus pic #3, but some sort of protection between the upper fork and the upper fork shroud. Also, it was not broken as in my earlier picture when I saw it. It was only split in one place, it was brittle enough that is snapped again when I removed it from the fork.

[gregp]

Yes, most dirt bikes have something similar. The WP forks on my KTM have a similar (black) split plastic ring that snaps into place on the bottom of the upper fork slider. Its sole purpose is to prevent the lower fork guard from rubbing the finish off of the upper slider tube.
In your case, it probably has a similar function, as your bike's fork appears to have a shrouded upper.
Generally, when they are new, they are thick enough, and flexible enough to open up enough to snap into place without disassembly.