I had a flat last night and replaced the tube on the road side without issue. Tonight I decided to have a second look at the repair just to make sure everything was OK - which it was. But while cleaning my bike after last night’s wet roads I noticed a small pin hole in the rim. It was actually just a small bump in the decal until I peeled the decal back. Even after peeling the decal, I still wasn’t sure if it was a factory hole or something else so I removed the tire and tube. From the interior side a much larger hole is present, and with a quick glance, I again thought it was a factory hole. On closer inspection, I could see that both holes were irregularly shaped, so it was clearly damage from the road. I do think I recall hitting a nail a few years ago - never would have dreamed it would puncture the rim.
Anyway, to keep the story short, I’m just wondering it there are any safety issues that I haven’t considered. The rim is a Fulcrum Racing Zero from about 10 years ago. It’s tubeless ready (not anymore), but I use tubes so that is a non-issue for me. The interior hole isn’t as big as a spoke hole - probably 2mm smaller. There isn’t enough room for rim tape, so I’m just going to put some adhesive tape over the hole. I’ll likely use 2 layers of packing tape (the red stuff used for vapour barrier), unless there is a better suggestion. I don’t have money for a new set of rims, so my hope is to put on some tape and carry on.
Thoughts?
Thanks
Jon
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Hi Jon!
Wow. I suppose a nail could explain that. 
I would say you definitely need structure there to support the tube. Tubeless tape seems like the obvious choice. It is thin and designed for that. Best would be two full wraps. (I say that because that’s the spec for road wheels. Maybe less would work but I don’t know.)
Of course no one can certify the safety of the rim, but that is a high quality part and rims have many holes in them and apparently it’s been working fine…?
- Tim
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Thanks for the input @TimMcClements . You sound a bit skeptical about the nail hole theory and I guess I am too. In analyzing it a bit further, I noticed the anodizing on the interior hole is perfectly intact - no where has it been scraped to bare metal. I would think if a nail had gone through, there would be some exposed metal. So because of that, I’m now going to guess that the hole was there from new and was probably present on the extrusion. I just never paid attention. I think because the anodizing is intact, I kind of assumed the hole was supposed to be there. And the other end of the hole (on the exterior surface) was covered by the decal.
And thinking about the nail theory, there would be no way to achieve enough force to drive a nail through the rim while just riding along. I probably couldn’t drive a nail through if I had a hammer.
Jon
Hi Jon! I’m sorry - I didn’t intend to sound skeptical 
I think it fits. If the wheel picked up the nail in just the right way, I could see that happening given momentum etc. But, ha, it didn’t make it all the way though the rim because that’s quality aluminum Perhaps the anodizing on the rim bed hole was protected by the tire/tube during puncture??
- Tim
If it’s a well used rim it is worth checking that there are no other cracks or lines coming out from the hole.
Assuming that it is a rim brake version you should also check the rim for wear, most wheelsets would have a a wear line or dimple that indicate if the wheelset is still safe to use.
Thanks for the thoughts guys. The wheel is in otherwise good condition, so I will continue to use it. And not that it matters, but I think my second theory is more likely (manufacturing defect). It actually looks to be two holes slightly offset from each other. And there is no displaced material from the hole present. More like it’s been punched out.
