Titanium (Ti) headtube tear: repair ideas?

[jkrienert]

Recently got an older Ti frame, and there is a few tears/cracks coming up from the bottom of the head tube. They are far from, and do not originate nor intersect welds. It looks like they were caused by the lower headset cup being slightly bigger than the ID of the headtube, or forcibly installed at the incorrect angle.

Anyhow, some diagnosis of the damage is important, but I am here to ask advice on how to best repair. I know of no Ti welders near me. I know I could ship to one, but I will need to save some $ for that. I would like to ride in the meantime, and I actually did already take it out before I discovered this anomaly. It rode fine, aside from some creaking, which I believe it originating from this damage.

The seller I bought it from said they were unaware, and rode it for many miles. I'm supposing they might not have even known it was there, and maybe its not 'that' critical. However, every time I look at it, I cringe. So I figure, the good people of ES might have some advice...

Here is what I have done:

• Ordered a 1.5" Gr2 Ti Hose Clamp (worm drive style) looks like 1.5mm band thickness? see photo below (anodized)
• Ordered a 1.5" Gr5 Ti Ring Clamp (bolt and nut style) looks like 2mm band thickness? see photo below (plain)
• Researched ALOT online about what to do, ideal is weld, sub-ideal is make a collar and press fit outside, which one of these clamps I hope to fulfill that function.

I got Ti clamps so its not dissimilar metal and potential site of corrosion. I'm supposing the ring clamp nut and bolt style will be better, because it doesn't have the cut outs for the worm drive, so its longitudinally 'stronger', its also Gr5 so an alloy that is slightly harder for tensile strength.

I'm thinking of:

1. drilling out three holes with a bit size that matches the wall thickness, at the ends of the cracks to relieve strain (blue rings in photo)
2. packing the crack and holes with bonding epoxy (not sure what kind yet)
3. thin layer of anti-seize paste around the bottom circumference of the headtube
4. mounting the Ti ring clamp on the anti-seize base, and tighten to snug

The anti-seize might be unnecessary or avoided. I don't know yet. I though about epoxying it to the frame instead, however I want to leave the option for welding open, and gluing seems like one way to contaminate the metal and decrease the quality of a weld.

Any course corrections or ideas are welcomed.
Grateful.

 

[neptronix]

I'm sorry, man.
It's possible that those cracks are starting to form higher than what you can see visually.
Some kind of clamp would not be adequate to make up for what's already quite compromised.

I don't know anything about working on TI. Maybe it can be welded. But i'm not sure how strong it would be after.
Maybe not strong enough if you're going to use it for ebike duty.

Hope you find someone with professional experience here.
If not, be willing to ship the bike to a specialist

 

[jkrienert]

@neptronix thanks for perspective. Sound like I need to save for a welder, and/or a new frame. I can move the parts over which is nice. This frameset is a matched fit for my body which makes the possibility of retiring it, tough.

Adding a scale bar for context...

 

[jkrienert]

What if I got a 1.5"id Ti tube of sufficient wall thickness (?) cut it lengthwise to make a collar (pink in photo), then shaped it to meet the downtube and top tube with bolt flanges (yellow), almost like a Ti lug?

In any direction I go with this, would drilling the tips of the visible cracks (green dots in photo) be a baseline must?

Maybe the carbon repair is more legit. It prevents the lower head tube from blowing out more than the deformation suggests it already is.

Then my.question what is best done on the interior of the head tube? Get a carbon tube segment that has an od slightly bigger than the id of the TI headtube. Then slice the carbon segment lengthwise (down the tube) resulting in a inner ID repair slieve that will spring compressing into place. Before doing that abrade, clean and coat the interior with the same epoxy as the outer wrap or collar...?

 

[jkrienert]

if you're going to use it for ebike duty.

I'd considered it a bottom bracket ebike candidate - though now that will not be the case without a reasonable repair.

 

[PaPaSteve]

Composite wrapping is a known and valid repair technique that can be done at home.
Here's and example :

Bacchetta 20 rebuild

Finding a short length of the correct size Ti tube isn't out of the question

https://www.titaniumjoe.com/

Having done a fair bit of titanium welding I still have a box of scraps, welding requires cleanliness and more time doing fit up then other materials.

 

[jkrienert]

Composite wrapping is a known and valid repair technique that can be done at home.

This is, interesting -

 

[jkrienert]

fair bit of titanium welding I still have a box of scraps

I dont have access to a TIG, nor the skills (yet?) to wield.

In sub. to finding a righteous Ti welder, is the suggested OD collar/clamp be reasonable? Its only about 7mm width around the circumference of the bottom tube base. I might have to deform (preferred) or grind one edge of the Ti clamp so that it is conformal to the OD of the tube and repair surface area.

Do they may 1.5" ID Ti seatpost binders/clamps .?. .that would be a couch size seat. Avoiding highly custom. Something simple, - maybe material isn't that critical, 304 stainless clamp with some sort of electrically isolating material along the clamp surface. I might be able to find both of those things locally...

edited: better wording

 

[n00b]

@neptronix thanks for perspective. Sound like I need to save for a welder, and/or a new frame. I can move the parts over which is nice. This frameset is a matched fit for my body which makes the possibility of retiring it, tough.

Adding a scale bar for context...

I would find someone who knows how to weld Titanium and pay them.

 

[jkrienert]

someone who knows how to weld Titanium and pay them.

This is the ideal. I might call around to some metal shops

 

[n00b]

This is the ideal. I might call around to some metal shops

Just keep your eye out and ask around for welders. I've come to know some and where some are over the years.
Places that advertise metal fabrication is a good start.
I was thinking the one dude's carbon bondo stuff might even be feasible too.
Inside and out. Somebody must have taken some big jumps with that thing and come down hard.

 

[OlderGiantFan]

It's a tough decision, repair it or bin it. I hope you make the right choice.

 

[jkrienert]

tough decision,

Oh, no question for me there buddy, repair all the way.

If the repair doesn't work, depending on failure, give another repair approach.

Then, and only then when putting some heart into brining it back to life to find no pulse, will I consider turning it into...
... wind chimes?

I tagged the top of the fractures with a fine felt marker and rode around the yard, over some logs, few jackalope hops, no propagation beyond the marks. I don't plant to continue stress testing though. It's light or nigh till repairs in order.

Even if I do carbon repair, or belt clamp and carbon, or any collar and possibly inset based repair (aka no welding), is opening the crack tips with a small drill bit still recommended? I'm supposing yes... Bit diameter matching headtube thickness? Remove fork so I don't have a holey shaft...

 

[jkrienert]

jumps with that thing and come down hard.

Yes ser. I was wondering if that's possible, some big endo case -ouch. It looks more extensive, than the tear a human could produce hammering a headset cup on before stopping and saying, "...should I be hammering this hard on this frame?”

Though, it's possible it's grown over time. The seller did suggest they were the OG purchaser from the builder, and they didn't notice the damage...

 

[PaPaSteve]

Depending on the tube diameter ? ? ?
Two piece shaft collar
or
Two piece pipe collar

 

[offGridDownUnder]

Recently got an older Ti frame, and there is a few tears/cracks coming up from the bottom of the head tube.

How comprehensive/certain is your inspection of the rest of the frame?

 

[jkrienert]

comprehensive/certain

After that discovery, more so in the last 24 hours...
There looks like compression marks in the Ti structure on the opposing side of the lower headtube. Though no apparent breech of the titanium oxide surface of the wall. I have not removed the fork yet ... That might be an important insight on triage of this.

Elsewhere I have not discovered any other indications of strain, stress, or failure of the frame.

I am... hooning it in the yard a bit. Watching the headtube marks I made every little while. No tear growth yet.

It is a wonderful bike. I have never ridden on this metal of the universe before today. There is a springy feeling that is like alchemy of aluminums responsiveness and steels shock absorption. Rather surfable.

 

[2old]

For me, the ramifications of a front end catastrophic failure are so potentially horrendous that I wouldn't consider anything less than an expert (like Moots if they do repairs) saying it was possible to salvage. Look up Ti welding; it must be done in an inert environment or you end up with Titanium Dioxide (the little particles that make white paint etc, white).

 

[Apartunis]

I would find someone who knows how to weld Titanium and pay them.

Note that welding titanium requires the part to be surrounded by inert gas on both sides instead of air. There are more people who can weld titanium than those who are equipped to weld it in oxygen free conditions.

 

[scianiac]

What do you guys mean you need to weld Ti in an "inert environment"? Any gas shielded welding is done in a somewhat inert environment, aluminum is just as reactive as Ti. That's what the shielding gas is for and yes you generally use pure argon for Ti and not a cheaper mix like for steel but that's not exactly exotic. For a tube section like that you also need to back purge the section but again that's not exactly exotic, you just seal up the openings with some foil tape and purge in argon.

Not saying you should just have some joe smoe weld it but welding Ti is not that crazy and you can probably find somebody who can do it.

 

[jkrienert]

I've continued to do light riding of the frame in the yard and back trail, and a little along the road side near the house.

The cracks have not propagated or changed from the marks I made. The frame as a whole is a beautiful construction and rides wonderful. I really can't fathom this being a reason to discard. At minimum, doing a really good job with a carbon repair seems like an option. I'm talking with tow line and unidirectional mat layered in multiple orientation relative to the principal directions of strain on the headtube and moreover that caused the tearing to begin with. The plan would maybe be, just make a carbon 'lug' that encases the entire headtube and the first few cm of the top and down tubes....

 

[2old]

If you're considering carbon repair, you might contact Craig Calfee (Designs). They've been doing this for 20+ years and provide a warranty.

 

[PaPaSteve]

Plenty of bamboo bicycle frame building tutorials online.
Calfee Designs also have kits to purchase
There was a Bamboo frame building class at one of the makers spaces where I used to work.
They used rolls of fiberglass orthopedic casting wrap material to create amazing strong frames.
A home DIY is a totally valid repair.

 

[jkrienert]

Bamboo frame building

This is a wonderful idea, and part of why I am darn near stubborn to repairing this.

I like that you mention this because, I made a bmx sized bike frame from bamboo in 2007 base on Craig Calfees work. Even had the pleasure of having an email conversation back and forth with him over it back then. Was awesome to have that level of connection between rider and creator. Anyhow, those bamboo tubes and their imperfections and nuances are... Well their a stretch but not completely dissimilar from the recent imperfections to this Ti headtube.

An intimate knowledge of the break, and the principal directions of strain this part of the bike faces with riding, would probably be enough to make it equivalent to its original build and lifelong in that repair too. That might be the most well considered option of all I'm presently considering. Does anyone have a general idea or even diagrams of numerical models showing the principal stress zones of a mountain headtube?

 

[PaPaSteve]

Wouldn't the layer wrap strategy of your BMX frame build be in the ballpark ?