Slider Wear

[rbell14]

i still have stock slides on my hyfax. Curious to know when they are getting too thin. Appears to me there are two fine lines, assume these are wear lines, to gauge how much is left. Is this correct?

I see two lines, which one is more important or what line tells you time to change?

 

[cannondale27]

First line. Has to be almost 5000mi on these my original set. Right at bend is where they wear. I keep these in truck for spares just in case my Duponts ever cant take the Mud runs!