Have just had an interesting exchange with someone on everyone's favourite online buying and selling platform who claims that Columbus SLX (with it's internal rifling or ridges) is especially vulnerable to trapping moisture and therefore internal rust rot. He claims he sees the tell-tale signs of this by the pitted rust at the vent holes on stays in the photo. Is this a thing? I've never heard of SLX tubes trapping moisture because of their internal ridges or spirals.

I think there are infinite variables that could never be accounted for as to "the why" one may see rust on a bike frame, let alone anything. The seatstays were never spiraled on SLX frames as Columbus writes, they're SL. So seeing rust at the vent holes of the SL tubed seatstays obviously has nothing to do with spirals. Where and how it was kept or ridden, whether the frame was treated inside the vent holes..... as I said infinite variables. At the point of sale, who cares(or knows) how the rust got there anyways ? All the excuses in the world won't change it. https://metal-guru.com/pages/columbus-tube-families

In most cases rust forms at vent holes because there are sharp edges that the paint doesn't cover well adjacent to an unpainted area. (the interior of the tube) This provides an entry point for moisture, same reason rust tends to form adjacent to the threads at bottle bosses.

There are no spirals in those seat stays.
Brent

Yep, I agree and what I have always understood. But this guy argues the rust has travelled or migrated to the seat stay vent hole from the chain stays and bb. Is that even possible?

Sure. Possible but improbable.
Rust is oxidized iron and forms from chemical reaction including water molecules and air. For rust to propagate, the moisture density would have to dynamically vary from one end to the other.
Not likely in a small volume like a chain stay. If the BB were openly exposed, maybe.
The mechanics doesn't matter, as stated.
Keep it dry to minimize rust. I have a dehumidifier in my garage where my bikes and tools are stored.

This is the extent of rifling in SLX tubing:


As you can see, there isn't much in the chain stays. I haven't seen any indication anywhere that SLX, or any other rifled tubing, is more susceptible to rust.

I've not noticed SLX being any different to SPX, SP, 531, 708, 731 or GTI. Sloshing diluted Waxoyl through my steel frames works well and there are lots of other gunges including diesel fuel.

Maybe the edges of the rifling are conducive to rust formation. There is more surface area with the SLX but not enough to be concerned.

How would it be possible for rust to migrate from the chain stays, through the solid rear dropouts, to the seat stays??

Clearly the savant on the online shopping platform has mastered telekinesis. The picture looks to me (ymmv) like straightforward surface rust under the paint caused by moisture getting under the paint at the weep hole.

Not exactly addressing your question, but my experience leaving stripped frames unpainted sitting in my shop (limited sample size)

Reynolds 531 - have them sit out forever and no (to minor) surface rust develops.

Columbus Cromor - I couldn't keep the rust off of this one frame I stripped to save my life. Even after a pre-paint acid etch, it would try to rust before I got the primer applied. And this was not a really rusty frame beforehand. It was wierd.


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