I remember some 25-ish years ago, when the first bonded aluminum frames came out (followed by bonded CF frames), that one of the arguments against them was that, eventually, at some day in the future, the glue bonding the frame together would fail, and you'd have a useless frame.

So, who here has ever had a bonded frame fail like this, either aluminum or CF? I'm curious as to whether the problem is anywhere near as bad as the naysayers predicted.

It's Epoxy, not "glue"..
America's Cup Racing Yachts and commercial airplanes use Composites,

you need to stop speculating.

do you even own a bonded bike frame? which one? how long have you owned & ridden it?

I don't, but I've been surprised at how many old aluminum-bonded frames I've seen on the used market locally.

We get Older and Our tastes may Change, over time..

I work at a big busy bike co-op and I see plenty of those older lugged aluminum and carbon bikes come in. Seems like they're still out there rolling.

They do occasionally come apart, typically at only one joint and are repairable if you think it is worth it. OTOH all the ones owned by
friends have had some sort of "corrosion" for lack of a better word where the clear coat is bubbled up and discolored at the joints.
This seems mostly cosmetic but suggests something is going on at or in the joint to cause this.

https://www.bikeforums.net/classic-vi...lue-other.html
https://www.bikeforums.net/classic-vi...rame-dead.html
https://www.bikeforums.net/bicycle-me...ti-6000-a.html

The question is about bonded frames specifically, not about composites or composite frames in general. The question does not apply to modern single-piece composite frames, for example.

What? Where exactly did the OP "speculate" about anytyhing?

Um... How is it relevant to the question?

Typically the more expensive/exclusive the item is the more likely any failure /flaw will be talked about. So while common 1020 steel frame may have seen greater numbers of frame failures then bonded frames have over the decades far more steel frames have been made then bonded. But we're likely to hear much more about bonded failures.


A common reason that a bonded joint fails is the lack of prep, planning, adhesive choice. Frame materials can galvanicly react to each other without the proper surface prep and joint design. Surface corrosion can creep in and under an adhesive, on the tube or socket surface, and cause adhesion loss. Fit up tolerances can be too far from needed ones and adhesive starts to become a structural member. To name the paths to failure that I think of.


While different joining/production methods do offer different results (weight, aero contours, material options) they also shift the frame production land scape. Sometimes these changes are not in the best for riders or the bike shops that service them. I could go off on a rant but I won't. Andy.

I bought a Trek 1420 in 1992 and my son still rides it. It's a bonded aluminum frame that's now 24 years old and has an absolute minimum of 30,000 miles and probably a lot more. So far, so good so they may eventually fail but this one hasn't.

I personally have never seen one of these Trek bonded frames fail but I've read a few accounts about those that have. It doesn't seem to be too common.

I've been using a bonded aluminum fork for the last 1 1/2 years, and don't have the history on it before I got it. So far, no issues.

I am now riding a Colnago C-40 with their rendition of bonded CF lugs and aluminum dropouts, and again no issues, but I've been riding it for a few months.

I was talking to a person yesterday with an older bonded aluminum Trek, I think. Anyway, apparently his DT shifters were were bonded on, and one fell off. He just glued it back on and it has been working for him.

Anyway, the bonded aluminum or CF seems sturdy in most cases, especially if there is some kind of a tight sleeve fit.

Since the naysayers, as usual, didn't have any actual experience with frame manufacturing technology "back when" but felt free to speculated anyway the dire predictions of doom were as valid as any other idle baseless speculation about "new" tech, and wrong in my experience as time has told.

My Vitus 979 has been in continuous service since '92, including road racing and lots of miles on our chip-seal roads at pace. Manufactured in a dedicated clean facility with the aerospace bonding tech of the era it's still all of one piece as of this AM's ride despite my best efforts.

This is not unusual or remarkable for a 979 frameset well matched to a rider of the suitable size/weight who is disinclined to running into stationary objects and/or curb jumping.

-Bandera

Had 2 AlAns in the 80s, metal Fatigue happened before any tube Join failure

Since I worked at a warehouse that distributed and repaired Vitus bonded frames I have to say: yes there were failures. Most of them were on early Carbone frames (carbon fiber tubes, aluminum lugs). As Andy pointed out above, these were apparently due to galvanic corrosion at highly stressed joints, usually the bottom-bracket-to-seat-tube joint.

I'd guess that later frame designs suffered fewer failures because designers incorporated lessons learned from earlier failures. Factor in redesigned lugs, layers of insulating material between tube and lug, tighter tolerances, and better adhesives and bonding failures became unlikely.

Carbon and Zinc are what makes a dry cell Battery.. 7000 series aluminum contains a % of Zn,

[MENTION=114799]Jeff Wills[/MENTION],

Do you recall what the failure rate percentage in service was for 979 and Plus Carbone framesets vs total production for each model?

We were a retailer of the line back when, had "a lot" of smaller/lighter customers and team riders on them and no doubt did business with your distributor.
Never saw a bond failure ( crash damage for sure ) on the 979 models while the Plus Carbone were only sold to dilettantes who never rode them anyway.

-Bandera

I bought my Raleigh Technium new in 1990 and have never regretted it for a second. Never have I had any indication that the frame (lugs) are having a problem. I ride it harder now than ever, and I have outfitted it with aluminum bonded forks and all high-end components from the 90's-2000's.
It gets its first "century" ride three weeks from now. I'm about to have it re-coated for the second time. I love it.

That's a very poor analogy but a layer of fiberglass in the joint prevents electrolytic corrosion in carbon tubes bonded to aluminum lugs. The presence of a low level of Zinc is not a factor.

Two friends had their late '80s Specialized Allez's come apart at the drive side chain stay to the bottom bracket shell. Both bikes probably had 20,000 miles on them.
I have a 2004 C-Dale 6/13 with no problems and around 15K miles. Bought a used System Six that has the usual corrosion, under the clear coat, where the carbon and aluminum meet.

I couldn't tell you- I was in the back warehouse, so I just saw what came in and went out.

The only thing I can offer is that we saw plenty of failures on Carbone frames. I can't recall one on a 979.

Yes, they come apart. They come part more frequently than lugged or tigged joints do. How often do they come apart is the real question. Probably not often enough to worry about it if the frames not corroded.


Don't let the wanna be engineers tell you nay different. And if they're real engineers they need to retire.

I had an '80s Alan and put 45,000 miles on it before the seat lug started to crack. I probably could have doubled that mileage, but someone was interested in the frame. I showed him the crack. He claimed he could repair it, so I gave him the frame. I should have kept the C-record headset. Doh!

There's also the issue of thermal expansion. Not an much of an issue when it's aluminum bonded to aluminum, but like galvanic corrosion, it's another compatibility issue when mixing materials.