Chainstay Crack

[jeo99]

Has anyone heard of titanium chainstay cracking because of a tire too large? There is a TI frame in the classified section that makes this claim. I am interested but concerned that a Ti chainstay would crack from tire rub! (been repaired)

:confused:

[Lifelover]

I was wondering the same thing but didn't want to derail his for sale post.

I do not understand the concept of what he means. I suspect he is not expressing the cause very well.

[jr59]

Why don't you contact blacksheep bikes and ask him?

[Kontact]

I've seen tire rub that left a very narrow wear channel in the stay. If it was deep enough I could see it being a stress riser that causes the stay to from there out.

Kind of like the way a carbon tube will crack starting at a small impact point.

[old_fat_and_slow]

How can somebody ride a bike (with the tire rubbing the chainstay) for a long period of time and not know it? I can sure tell the difference in rolling resistance when my tire is rubbing.

I can see on a steel bike rubbing the paint off. I can see on a composite bike maybe cutting a gouge in the matrix material.

Titanium wearing away due to tire rub. Seems highly unlikely, at least to me. Seems more likely the tire would disintegrate before wearing the Ti away, same with steel.

As long as it was repaired, and the repair is invisible. I wouldn't have any problems buying the bike.

[atanz]

it could be from abrasive debris catching on the tire and wearing away the material. I have some pretty deep scratches on the inside of my carbon fork's crown eventhough the tire has plenty clearance. leaves and sand have gotten caught there and rubbed before I knew it.

[old_fat_and_slow]

it could be from abrasive debris catching on the tire and wearing away the material. I have some pretty deep scratches on the inside of my carbon fork's crown eventhough the tire has plenty clearance. leaves and sand have gotten caught there and rubbed before I knew it.


Yeah, that makes sense. I didn't think about the debris aspect, since I'm a fair weather biker, mostly. :D

[Kontact]

How can somebody ride a bike (with the tire rubbing the chainstay) for a long period of time and not know it? I can sure tell the difference in rolling resistance when my tire is rubbing.

I can see on a steel bike rubbing the paint off. I can see on a composite bike maybe cutting a gouge in the matrix material.

Titanium wearing away due to tire rub. Seems highly unlikely, at least to me. Seems more likely the tire would disintegrate before wearing the Ti away, same with steel.

As long as it was repaired, and the repair is invisible. I wouldn't have any problems buying the bike.
A friend did damage her titanium stay this way. The seam line that sticks out between the tread and sidewall wore a 2mm wide groove into the stay after the QR shifted in the horizontal dropout. It didn't produce much drag, but it wouldn't need to over a mile to do the same work as five seconds with a hack saw.

Straight gauge Ti tubing is 0.9mm thick and softer than than tool steel. It really doesn't take much mess it up.

[John M]

I would consider that frame as good as new since that is a reputable builder.

[DRZRM]

Yeah, a buddy rubbed a hole in a ti MTB chain stay many years ago. His skewer would shift in the frame under force, over time it caused a hole, likely more an issue with knobbies, mud and sand.

The frame in question looks to be as good as new, the builder replaced both stays.

[jeo99]

Thanks Guys/Gals! The usual good feedback. Never heard of this issue but now I know.

:beer:

[fourflys]

How can somebody ride a bike (with the tire rubbing the chainstay) for a long period of time and not know it? I can sure tell the difference in rolling resistance when my tire is rubbing.


could have only been rubbing when accelerating or standing to climb.... My Litespeed had some rub marks from my rear tire, which I assume are from that since it spun freely on the bike stand...

***just read the FS ad... my question is why would anyone build a bike (especially Ti, usually a long distance bike) to ONLY fit 23mm tires? :crap: unless that was specifically asked for, I gotta wonder about the builder...

[lonoeightysix]

I've seen tire rub on interior chainstays on quite a few "noodly"-classed Ti MTB frames.

[lonoeightysix]

I think it's a combination of stay flex, wheel flex/slipping, and road debris on the tire.

[mgm777]

Not trying to add fuel to the fire, but as another poster noted in the classifieds, take a close look at the dog in photo. Too funny! Not saying this has anything to do with issue being discussed, but funny nonetheless.

[ultraman6970]

How u cant noticed? I mean people just go a ride like crazy monkeys w/o even looking?? Its just look at the bb area from the saddle while riding to figure it out if the wheel is not at the center. In MTB bikes friction shouldnt bring some kind of noise coming from the blocks in the tires or something? Sorry man... doing my own mechanic since im like 13 y/o, negligence of the rider in my opinion.