What causes this type of belt damage

Hello guys, pretty self explanatory, anyone experienced this damage pattern on the belts? My guess is that my idler bearing diameter is to small (13mm) and is shearing the surface when heat and tensions are combined.

Maybe a rock got it?

belt might be too tight. or a rock got in between the belt and the tensioner.

Didn’t think of it, but it’s possible, since i put the tensioner I’ve been running the belt very loose without problem, and because of that the rock didn’t puncture the belt

And another thing, re evaluating my belt cover, if a rock enters it, there’s great chance that it will be forced between the between the belt and the idler

can you give a pic with tensioner being seen in a picture?

I think you might have rolled over something sharp… and it just pierced your belt… otherwise… no other ideas what could cause this :slight_smile:

If the damage would have been spread over all belt… then it might be something ‘‘regular’’ happening… I assume the damage is done only in one place…

Black blob is rock. Nothing stopping this from happening. Just a possibility or maybe you just got unlucky and got a bad belt.

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That’s a rock


I have this damage on 3 points around the belt, at random locations, it’s probably little rocks entering the belt cover or as Sorrentino said, on the road, my previous pulley had a smaller diameter, so this didn’t happen

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The belt tensioner…

Hence more chances for a Rock to get lodged than people without a tensioner

Probably, but without it no way my setup is gonna work, but I think most of the damage happens because the situation SORRENTINO described

Another belt gone today, there’s no way I can avoid the bigger rocks all the time, or I will be run over, hubs may be the solution for the roads condition around here