Rust on a Ti bike @ bottle cage bolts

[Dino Suegiù]

Can your friend inspect the frame, for this and other possible issues?

At the very least, have your friend ask the seller to remove all 4 bottle cage bolts and photograph all of the rivnuts carefully, if the frame cannot be viewed in person.

I would be less likely to buy a ti frame that looked like that without being able to inspect it myself...unless this is a really special frame, there are so many ti frames for sale now, often in truly mint condition.

[Marin]

Remove the rivnuts completetly and replace, ideally with stainless ones.

[MikeD]

Originally Posted by Pegoready

Welding produces a lot of heat, and one could make the argument that it's a lot better to drill a hole and rivnut it on a lightweight, often-butted tube. This is the kind of thing that can happen around welded bottle bosses that are overheated:



I've seen Firefly actually reinforce the area all the way around with what looks like a welded ring in order to use welded bosses. Hats off to them. It's an extreme solution to a simple problem, and most Ti manufacturers aren't going to go through the trouble to do this.



The other argument is if you cross-thread the bottle bolt, it's a lot easier to replace the rivnut than fix the threading on a welded boss.

A hole drilled in the frame is a stress riser and rivnuts don't reinforce it very well. I had a Trek aluminum bike where the frame cracked through at a rivnut holding on the front derailleur braze-on. I'd rather have a welded boss.

[Butch]

I was at Moots for ~18,000 frames built with welded in bosses and maybe there were a couple that had issues. Some of those tubes were thin 0.7mm. Just depends how the preparation and welding is done and where they are located IMO.

[FriarQuade]

Originally Posted by Butch

I was at Moots for ~18,000 frames built with welded in bosses and maybe there were a couple that had issues. Some of those tubes were thin 0.7mm. Just depends how the preparation and welding is done and where they are located IMO.

Bingo. Welding isn't inherently flawed in any way. But it is a process that depends on a certain level of preparation to ensure it's reliable. Same thing goes for rivenuts though.