Removing a fillet-brazed head-tube

[edelbikes]

Hi !
I have fillet-brazed mtb frame on which a small crack has started to appear: it's vertical, on the side of the HT, just in front of the down-tube fillet... A bit weird, but hopefully it was detected before it became catastrophic...
Now I'm looking for some advice on the best way to remove the HT... I was thinking of cutting everything as close as possible to the DT/TT tubes, but I will be left with two rings which will be quite hard to remove...
Thanks for the suggestions !
Francois

[steve garro]

Just do a full front triangle replacement - it will be allot easier to do, and you won't have the double heat cycle on the TT and DT and then have to warrenty the cracked front triangle.
Do cold removal - hachsaw, files, grinder, sawsall.
Was it an 853 headtube?
- Garro.

[edelbikes]

No, the HT was a standard 37mm tube with the middle part very slightly reduced on the lathe, down to ~36.5mm. I'll check the thickness once it is cut, but I will probably avoid this solution on the next frames, except for very light riders !

[Stijl Cycles]

Just do a full front triangle replacement - it will be allot easier to do, and you won't have the double heat cycle on the TT and DT and then have to warrenty the cracked front triangle.
Do cold removal - hachsaw, files, grinder, sawsall.
Was it an 853 headtube?
- Garro.

Garro,
Won't replacing the down tube and top tube just create double heat cycles at the BB and ST?
If I had to choose a place to put my double heat cycles, I don't think I would choose the seat tube, and at this point the BB has already been faced to size, will there be enough left after another shrink cycle from the DT joint?
Maybe it's just me, but my trouble areas end up at the seat tube, so I try not to mess with it if I can.

Francois,
Not that you asked, but the likely cause of the crack is from over heating of the joint or undercutting the HT during finishing. Probably some of both.
I've done it enough times now, but at the seat tube...
I would almost suggest cutting away the head tube, but leaving the filleted area and the remaining HT behind to use as a backer plate. Clean it up on the ID and silver a new head tube right over it. Or braze it.
Or non of the above, chalk it up to learning, and make another frame from scratch.

Hh

[Chauncey Matthews]

Go with Garro my son ;)

[edelbikes]

The main thing bothering me with a full replacement "a la Garro" is that there's a triple internal cable routing in the top-tube (something i will never, never do again !). The cleanup of the DT/BB/ST junction also seems like a nightmare...
I'm wondering if I'm not going to cheat a little bit by reducing the frame length by a few millimeters, like this I could put it in the mill to cut new miters right behind the remainings of the HT. It's a full rigid frame so there's no issue with DT/fork clearance.

Here's a pic of the nearly finished frame, I couldn't find a post-braze pic of the DT/HT joint:

Full view par Edelbikes, sur Flickr

[steve garro]

Garro,
Won't replacing the down tube and top tube just create double heat cycles at the BB and ST?
If I had to choose a place to put my double heat cycles, I don't think I would choose the seat tube, and at this point the BB has already been faced to size, will there be enough left after another shrink cycle from the DT joint?
Maybe it's just me, but my trouble areas end up at the seat tube, so I try not to mess with it if I can.

Francois,
Not that you asked, but the likely cause of the crack is from over heating of the joint or undercutting the HT during finishing. Probably some of both.
I've done it enough times now, but at the seat tube...
I would almost suggest cutting away the head tube, but leaving the filleted area and the remaining HT behind to use as a backer plate. Clean it up on the ID and silver a new head tube right over it. Or braze it.
Or non of the above, chalk it up to learning, and make another frame from scratch.

Hh

Do not do this.
HH your bad experences with ST junctions are something you are doing wrong, and should not reflect on this matter.
Instead figure out what you are doing wrong at your ST junction.
And, if you are a good brazier facing a BB takes what - 5min?
You DO NOT want to snap off a headtube, and the "Just add it to the remainder of the HT bits" is......................Ghetto.
Sorry.
- Garro.

[steve garro]

The main thing bothering me with a full replacement "a la Garro" is that there's a triple internal cable routing in the top-tube (something i will never, never do again !). The cleanup of the DT/BB/ST junction also seems like a nightmare...
I'm wondering if I'm not going to cheat a little bit by reducing the frame length by a few millimeters, like this I could put it in the mill to cut new miters right behind the remainings of the HT. It's a full rigid frame so there's no issue with DT/fork clearance.

I didn't say it wasn't going to suck - I said it was the proper way to do it.

Think of the end user - overheating the most majorly stressed areas on the frame is going to farther limit it's lifespan in a serious manner, and likely you'll see it come back again and maybe more fucked up..........maybe the person, too. I just think you can't be too careful with the front of the triangle - we all have to agree that's where the most drastic and painful failures happen, no?
You just had one.
If it's yours, sure rock it - but if it's a clients do it right.
It's part of the deal, and if you do this long enough you will have more - I get a frontal impact damaged bike around once every other year - roof racks, trees, boulders........I do use straight 37mm Verus HT so I've never had one crack, but have seen plenty.......
I'm sorry if you were hoping for an "atta boy - it will be just fine" but I'd do it right and safe - can't be too safe - sorry about the triple internals - damn I'm glad I don't do those.
Sucky - Sorry, F.
- Garro.

[edelbikes]

Thanks Steve for the wise words, you've convinced me.
Perhaps I would have gone the "quick and dirty" way if the customer had told me that he was going to retire his frame or use only for small commuting, but I know that he really values his frame and plans to ride it for a long time. So that's a good opportunity to use slightly stronger tubes (probably 853 DZB), and sleep well... ;-)

[steve garro]

Thanks Steve for the wise words, you've convinced me.
Perhaps I would have gone the "quick and dirty" way if the customer had told me that he was going to retire his frame or use only for small commuting, but I know that he really values his frame and plans to ride it for a long time. So that's a good opportunity to use slightly stronger tubes (probably 853 DZB), and sleep well... ;-)

Good On Ya.
You will sleep better and that is priceless.
And, your client service will pay forward for you - it will not be in vain - blog the shit out of it as it shows you care!
Thanks for doing that - Steve.

[Stijl Cycles]

It must just be staring me in the face, but why is it better to have a double heat area at the BB and ST? Wall thickness of these tubes?
I honestly desire to know.

Hh

[Chauncey Matthews]

It must just be staring me in the face, but why is it better to have a double heat area at the BB and ST? Wall thickness of these tubes?
I honestly desire to know.

Hh

Post#8. Second sentence.

[Stijl Cycles]

I think I understand now.

It's about future potential for the tubes and joints to take induced stresses from impacts such as crashes which typically occur at the front triangle.
Yup, makes perfect sense.

I guess I was just caught up in the thought of the potential for tube failure similar to the original problem caused from a second heat cycle or under-sizing the BB shell from re-facing it.

Thanks.

[edoz]

I've had to do a couple of repairs so far, one chainstay cracked behind the bb and one buckled ht/tt from an impact and I've decided that I'm only going to to front end or rear end replacements. Seems counter intuitive, but cutting the whole thing off and starting fresh can often be easier in the end that trying to salvage as much as possible.

In my real jobs, I've often found myself in the situation of bargaining with the boss over how much stuff they want to absorb the cost of when I throw it away vs how much grinding I want to do to save the old parts. Just my $.02.

[Britishbane]

I didn't say it wasn't going to suck - I said it was the proper way to do it.

Think of the end user - overheating the most majorly stressed areas on the frame is going to farther limit it's lifespan in a serious manner, and likely you'll see it come back again and maybe more fucked up..........maybe the person, too. I just think you can't be too careful with the front of the triangle - we all have to agree that's where the most drastic and painful failures happen, no?
You just had one.
If it's yours, sure rock it - but if it's a clients do it right.
It's part of the deal, and if you do this long enough you will have more - I get a frontal impact damaged bike around once every other year - roof racks, trees, boulders........I do use straight 37mm Verus HT so I've never had one crack, but have seen plenty.......
I'm sorry if you were hoping for an "atta boy - it will be just fine" but I'd do it right and safe - can't be too safe - sorry about the triple internals - damn I'm glad I don't do those.
Sucky - Sorry, F.
- Garro.

I wanted to comment on this thread a while ago with my experience having a fillet brazed head tube replaced and now that I can due to the new forum rules, I will. I had a head tube fail just below the down tube, reamer most likely took out too much material. I sent it back to the builder, who kindly and quickly replaced the head tube only (thread on VS somewhere re: that repair). As Dave Kirk called, and as Garro mentions above, the repair lasted all of a couple months before the top tube and down tube started failing as well. BIG 'ol wrinkles forming right near that replaced head tube. Once again the builder stepped up and this time replaced the who front triangle. Large waste of their time (zero revenue coming in and lost time working on revenue producing work) and missed riding for me as this was/is my only ride.

My two cents...FWIW.

[steve garro]

I wanted to comment on this thread a while ago with my experience having a fillet brazed head tube replaced and now that I can due to the new forum rules, I will. I had a head tube fail just below the down tube, reamer most likely took out too much material. I sent it back to the builder, who kindly and quickly replaced the head tube only (thread on VS somewhere re: that repair). As Dave Kirk called, and as Garro mentions above, the repair lasted all of a couple months before the top tube and down tube started failing as well. BIG 'ol wrinkles forming right near that replaced head tube. Once again the builder stepped up and this time replaced the who front triangle. Large waste of their time (zero revenue coming in and lost time working on revenue producing work) and missed riding for me as this was/is my only ride.

My two cents...FWIW.

I swear to god I don't make this shit up.
Thanks & glad you are still with us.
- Garro.

[steve garro]

IMG_3777.JPGJust to make you feel a little better - another "how do I fix this" moment, but I think I have it - a first, broke after 10,000+ miles of mostly singletrack.
1/2 a day and it will be good as new.
- Garro.

[edelbikes]

Or you could start a new trend... Someting like "virtual seat-tube frames"

[orange71]

Hi all

I am the owner of the frame. Francois has been great about all of this, I appreciate it must be a nightmare for him, especially the internal cable routing

He is correct though, I do really value the frame and hope to use it for a lifetime. It was my 40th birthday present. I get so much pleasure from it. Repairing it properly, as he will be doing, will mean we all sleep well!

Ed

[steve garro]

Or you could start a new trend... Someting like "virtual seat-tube frames"

It WAS mighty flexy when i cut the ST out!
Looks like your client is already stoked - this stuff pays forward for you, I swear.
- Garro.