cajunpedaler

Cracked head tube, aluminum



I found a Zydeco frame. It fits me. I am a short captain, and it is so hard to find a tandem that fits. And within budget. It's either a 2005 or 2006. Going through the bike today I discovered a cracked head tube. It is not simply chipped paint. I bent an end of a straight pin and felt around inside of bearing race gap and there is a ping where crack goes all the way through. Better to discover in my workshop than on a screaming downhill...Right?

My mechanic mentor tells me this is not a death sentence for this frame. I need to find a good aluminum welder. And once I do that, what instructions or do's and don'ts do I give this welder? Any pitfalls I should expect. I could care less about the cosmetics. I want it to be safe and sound.

Any suggestions?

I noticed while searching that there is another monstrous ugly discussion about aluminum head tube. I don't want this to get ugly.


Thanks.
Perry

twocicle

Lots of duct tape and rubber bands.

CliffordK

https://www.bikeforums.net/bicycle-me...ck-repair.html


Ok the wire and glue might work, but your stoker might not appreciate the aesthetics.

So, back to your welding. Bring your headset cups with you. After the welding the headtube will have to be faced and reamed to give a tight fit of the bearing cups. Was it too tight causing the crack?

You might also talk to your LBS to see if they have the proper facing and reaming tools.

FBinNY 

Aluminum head tubes are prone to cracking because corrosion expands the effective cup diameter stressing the tube radially. It's as if you pressed in an oversize cup. This is becoming more common as time catches up with aluminum bikes produced years age.

I have a pair of bikes with cracked tubes, which I chalk up to cheap, unplated head set cups rusting, and example of the high cost of cheap stuff - Grrrrrrr.

Anyway, I've elected to do nothing, because I'm not convinced anything is needed or will make a difference. I expect that the crack will grow over time, and at some point I'll need to decide whether to try a repair or ride the bike until I can't.

If the frame is cheap enough, and as you say frames that fit you are scarce, I'd buy it, unless this was going to be used heavily, in which case I'd think about it harder.

FWIW - a split headtube (even fully split) isn't likely to cause a crash, though I wouldn't start out knowing one was split along the entire length.

Your decision has to be based on the economics and specifics of your situation, so take some time and think about it then act accordingly.

BTW - somewhere in the linked thread, I'd posted details of a number of ways I'd consider "fixing" the issue.

Philly Tandem

Assuming this isn't your tandem already, I'd think thrice about buying this with a cracked head tube, unless you can basically buy it for the value of the components only and view the frame as a wildcard. Is the current owner the original owner? If so, he/she might be able to get some warranty consideration from Burley. Even though Burley has reconstituted itself as a new company, apparently there is some possible compensation available. See post #6 in this thread (admittedly from 2010, so things may be different now): https://www.bikeforums.net/tandem-cyc...y-history.html

Also note the estimate in that post for a Burley headtube repair: $1000. I personally would not gamble on fixing it at a lower cost.

twocicle

OMG Cliff (post #3 ), I was joking about this, but your photos do fall into that category

Seriously though, if you can get the AL repaired cheaply and be sure the crack will not spread, then my opinion is that trying to fix it could work ok. Reason being the headset takes most of the direct stress. Likely the crack was a result of too tight a headset cup fit. Perhaps the repair could include some extra reinforcement added in that area, like adding an external metal band around the lower part of the head tube.

I wouldn't spend more than $100 to fix it, otherwise shop for a replacement frame.

CliffordK

Not my photos. That was another recent post with a cracked aluminum headtube.

As FBinNY mentioned, a bit will depend on one's use, and where the crack is. A crack on the front as above would likely progress, but the front end won't just fall off without warning. Sloppy steering?

A crack on the rear of the headtube, on the other hand, might lead to a more critical failure.

So, if one is just tooling around town, then just watch the frame. If one is doing a cross-country tour, then either get it fixed right, or replace.

Part of the point of this post was that the OP had a special tandem frame that he liked. So, replacing it might not be an easy option. Bike Friday, and a few other brands should be able to support a short Captain, but the cost is much higher.

So, if one could do a permanent repair, it may well be worth significantly more than $100 to the OP.

In the post above, the person used wire and epoxy. But, one could also do a similar repair with epoxy and Carbon Fiber, Fiberglass, or even Hemp. It would mask the crack, but maybe that is ok (if it is in a non-critical spot).

cajunpedaler

I already bought the bike. It was a 7 hour drive for me to go pick up the bike. At 6 hours into the trip, I got violently ill with a norovirus. The seller graciously came the last hour to my motel, where, between vomiting and diarrhea bouts, I gave the bike a cursory look see. I do not for one minute believe the seller knew about this crack.

OK so now I own a bike with a cracked head tube. This bike is made from 7000 aluminum. According to the guy at Tandems East, this aluminum is annealed. He says that welding it, will actually make it weaker.
My mechanic mentor did not mention anything about the annealing, and said welding should be fine.
Another bike shop said, it's junk.

I could care less about cosmetics.
With this additional information about the aluminum, any ideas...or suggestions.
Tandems East has another Zydeco bike. It's steel. I don't want to buy yet another used tandem, but at least if it's steel..I won't have the aluminum issue...

Perry

FBinNY 

In case you didn't search it out, here's my pot on a related thread.

--------------------------

Let's try to separate the wheat from the chafe a bit.

First of all, understand the likely cause, which is corrosion, most likely rusting of the steel cups, which expanded the rube beyond it's limit. It is not related to any stresses, so likely will be self limiting even if you do nothing, though you do want to knock out the cups, and stop the corrosion process (I'd use a zinc based paint).

Secondly it's not likely to be dangerous, because even id the tube splits over it's entire length, where are the fork and headset going to go.

I have similar cracks on my two bikes in Cozumel, the result of a crappy painted steel headset, and the island's high humidity and salt air. I've elected to do nothing, and if and when the tube is split enough that I get headset float (not yet so far), I'll decide whether a repair is warranted.

As for what the OP is doing, the tube has to be under some ring tension to keep the headset tight. So, before reinforcing it, the head cup should be removed, and the tube pulled closed. That way there'll be tension when the cup is pressed back in.

IMO, the best repair would be a steel rings fitted to both ends. Next, would be steel wire wound with as much tension as possible in the type of tight array used to secure fittings to fishing poles. Third, and easiest, though probably shortest lived, would be to remove the cups, clean everything as well as possible, then bond the cups in with high strength adhesive.

Some of the methods can be combined, like wound wire + bonded cups, but there are no assurances, and it's all only a question of slowing a terminal process.

rm -rf

I remembered seeing a glowing review of this wire clamp tool. Clamptool site. Howto pictures

They also have stainless steel wire. This would make a strong and neat reinforcement with multiple wraps of wire.

twocicle

However there might be some issue with interaction of the AL tubing and many of these other materials, ie: steel, carbon. Shelve it and smoke the hemp

FWIW, way back in the day when I couldn't afford much, I had a very successful season racing on a steel road frame with a cracked bottom bracket and seat tube lug. Oh, the fork was also bent so that riding no-hands required leaning way over to one side. I got that frame next to free and enjoyed it very much. It wasn't fatal. Many of my subsequent custom team frames never felt as good as that "piece of scrap".

FBinNY 

Thanks for the lead, I'll probably buy one of these tools.

fietsbob

I would hope the aluminum welder knows his job better than we do..



Prep Done often, prepare for the weld filler bead by cutting a V in the metal where the crack is to get a clean surface .
new work does get prepared like that for initial welding..



belt & braces .. adding a Machined ring of more metal around the bottom edge perhaps.. as reinforcement?

Squeezebox

If it were me , I'ld probably also go to clampring, and not do a DIY.
Good luck!!

dvs cycles

A friend's Santana Sovereign had a crack develop in the HT. Took it into Santana and the welded it and machined the welds down, repainted it as good as new. No Charge.

loky1179

I've been meaning to share my little story. The beginning of the story of my cracked aluminum frame is detailed here:

https://www.bikeforums.net/commuting/...ike-blues.html

What I didn't share is the ending! I tore the bike down and was going to throw it in the trash - but a good friend of mine is a professional welder. He took a look at it, and said "No Problem"! I've now ridden the bike through another winter, and no more cracks as of yet.

As always, its not what you know, its who you know . My buddy guaranteed me the welds would not break, however, just beyond the welds is another story. The frame was not heat treated after the fix - but I don't know if it was when it was originally built for that matter. And he fixed for free - though I guess a bought him a 12 pack of beer for his troubles.

Before:



After:

cajunpedaler

The last reply gives me hope. According to one aluminum welder I talked to it is probably doable.
Did you also weld the bottom bracket crack? Didn't see photos.
Did your welder bring out a v in the crack first?
Thanks.
Perry

loky1179

Yes, he did fix the bottom bracket as well. I was going to start my own thread to show off the pictures

He did this at work, so I didn't see what he did, but he said he cut a v in the cracks. He said he had to be careful to control the depth of the weld, or the bottom bracket threads would have gotten trashed. Which is why, I believe, he used multiple smaller welds to do the fix.

He had to weld over the cable guide screw hole on the BB - and he tapped me out a new hole. I just added a little Sugru under the cable guide when I reassembled it, to stabilize it.

Oh, and he didn't leave grease in the bottom bracket or head tube when he welded it. My friend wanted to make sure everything worked, so we put in the head tube cups and bottom bracket to make sure everything fit after it was fixed. I put a coat of paint on before assembling the bike.

loky1179

Note, your welder should know this but, here's a good expanation of heat treating. Aluminum welds produce weak areas:

https://www.lincolnelectric.com/en-us...qs-detail.aspx

I know my fixed bike is going to weaker at the edge of the welds. It doesn't really worry me - especially now that I know the frame material is prone to cracking, I give the bike a pretty good inspection at every tuneup. I'm just using it as a commuter on mostly smooth trails.

Also, my head tube crack was on the front of the bike, not where I'd imagine the highest stresses are on the head tube. The bottom bracket crack was due to a rusting (expanding) cable guide bolt. I replaced it with a well greased stainless steel bolt.

And my fix was free. You'll have to weigh the cost of paying someone to fix it vs the cost of buying a different bike.

Just wanted to throw that in there to muddy the waters for you

mtnbke

You get what you pay for with Aluminum frames.

Back in the good ol' days before aluminum welding technology took several leaps forward, welding aluminum bike frames required absolute master welders compared to steel. This the era of epic master crafted US built frames like Cannondale, Klein, and Morgul Bismark. While many people absolutely loved the ride quality of Durango built Yeti frames, and those aluminum Yeti ARC frames proved themselves to be just as exceptional as the Cannondale, Klein and Morgul Bismark frames many many vintage Yeti frames were retired due to cracks at the head tube, seat tube etc. Which is sad, because those frames are irreplaceable and vintage US aluminum bikes on a weight, acceleration, stiffness and performance basis were top shelf.

Aluminum is not a strong alloy, if it hasn't been heat treated. You can't just take an aluminum frame to a local welder that TIG welds aluminum trails, for example, and have him lay a bead and assume the bike is safe to ride. Welding on a aluminum frame negates the heat treating. When an aluminum frame fails even if its a priceless vintage Klein, Cannondale, Merckx, Pinarello, Morgul Bismark its done. There will be warping from the heat from the repair weld that will distort the frame and make it want to crack over time. Sadly, an aluminum frame that has developed a crack is indicating to you that there were already existing tension problems in the frame, or there was a poor weld.

Klein/Cannondale used to use master welders and had trouble holding on to them. These master welders would leave to go work for defense contractors and chase the big bucks. Back in the day welding on aluminum was orders of magnitude more difficult than it is today with modern welding technology. This was in the days before welding technology and current wasn't computer controlled, when there wasn't start-up and bead end current control adjustment, when there wasn't feed stock speed adjustment. Cannondale used to offer a lifetime warranty on their frames because of the perception of aluminum cracking. Most of us in the industry have seen a hundred cracked Yetis for every cracked vintage Cannondale or Klein. Morgul Bismark frames were so rare that you just never see them period.

I would never EVER advocate trying to repair an aluminum bike frame, especially a tandem that has dynamic loads being placed on the frame. A titanium frame is completely repairable. Lynskey, Lightspeed, Moots, and Merlin ti single frames crack a lot, and there are plenty of frames on the road with multiple repair welds on them. They are "as good as new." However, an aluminum bicycle frame, let alone a tandem aluminum frame that has developed a crack needs to be retired. Any attempt to repair the frame is going to warp the frame and place the tubes under out of alignment tension. A crack is a great indicator of the frame having other tension problems due to warpage. You can send a carbon frame with broken tubes to Calfee and have it repaired, and it will probably be stronger than it was new (although it will have added a gram or two). You could I suppose have someone like Nobilette remove a crimped steel lugged tube and replace it with another tube, although the expense of doing that and the repaint on a steel bike would require it truly having been a special bike to begin with. Aluminum, just can't and shouldn't be repaired.

Its your frame and your budget, but in my opinion that frame is dangerous and needs to be retired. No one should ever, reasonably think they can repair an aluminum bike frame and have it be considered "safe" to ride.

Mayonnaise

I was reading through this post getting more and more angry, wanting to shout "are you people out of your minds"...what if your delightful nephew is riding with you, or your precious grandchild??? You gonna ride a cracked frame??

Then I read the voice of reason. Thank you. I'm going to take a nap now.

cajunpedaler

Mmmm...I hope the nap helped. I was enjoying the anecdotal tone of "been there, done that" or "fix it" or "don't fix it". And then the emotionally laced "priceless grandchild" crap....sounds like a passive aggressive statement just to start shi*.
Mechanically,some things CAN be fixed, y'know?
Besides, I think a blowout on a front tire would make a huge crash. So therefore,we all live in a paranoid bubble and never venture into anything?

cajunpedaler

I am on the fence about a repair to the aluminum. It is aluminum 7000. The alloy it's mixed with is zinc. I have talked to a couple of what I consider knowledgeable aluminum welders. One is comfortable with working with the aluminum, the other guy is unfamiliar.
I have found another Zydeco frame It's steel. Burley only made them aluminum for the last 2 yrs of production.
I will repair the aluminum frame and will report findings..
I have really appreciated the discussion. I learned a lot. Thanks all.
Perry

mrchaotica

Assuming there's enough clearance between the bottom of the down tube weld and the bottom face of the head tube (or the top of the top tube weld and top face of the head tube, depending on where the crack is), clamping or pressing on a stainless-steel ring around the outside of the top tube seems pretty reasonable and safe to me. (Actually, if I were considering such a repair I'd probably do the top and bottom, just in case.) I'm not a bicycle mechanic or frame builder (and although I am an engineer, this is not professional advice), but I'd expect it to be at least as strong as a steel head tube afterward. It might be cheaper than welding, too, depending on whether you can find stainless steel tube of the appropriate inner diameter and thickness without having to machine it.

cajunpedaler

Actually, putting a ring on the top and bottom has been one of my considerations. There is clearance, both top and bottom. And I have a circle of friends who are machinists.
Thanks.