verktyg 

Trakhak, I rewrote my post and separated the issues of adhesive failure and cracked aluminum seat lugs.


I don't see it that way... With the exception of the forks on Teledyne Titan frames, C&V steel and titanium frames will usually give some warning of impending catastrophic failure. To a lesser degree, aluminum frames too.

Creaking sounds or any increased flexibility or change in the ride of a bike should be checked out.


Where there's smoke sometimes there's fire.... With the ease of posting photos online, reports of failures become more than anecdotal rumors.

I mentioned above that I've seen a number a glued Raleigh frames with separated tubes listed cheap on eBay.

Those Raleigh Dyna-Tech and Raleigh USA Technium frames were only produced for a few years.

One advantage for gluing those frames together was reduced manufacturing costs - They didn't have to have skilled employees to braze lugged frames or weld lugless frames.

It was a noble experiment that didn't last long. They were made to sell not to last! Throw away consumer products!

BTW, Raleigh in the UK used investment cast aluminum lugs with internal sleeves on their Dyna-Tech models. The tubes were also mitered - see picture.

The glued together frames were an attempt to adapt new technology to a 100+ year old bicycle frame design. The trial and error process - 30+ years - took Waay too long.

Eventually frame designs where developed to take advantage of the strengths and weaknesses of the material technology i.e. modern CFRP frames.

verktyg

Chas.

CoRide59

I did some Googling and web surfing, looking for some added information on any issues with the Specialized Epic line, and perhaps to find out when they insulated the tubes from the lugs. I found some posts by Bryant Bainbridge of Specialized. From 1980 - 1990 he was director of R&D there. He commented that as he wasn't there at the time he doesn't know when the insulating started, or if it was done on the '93 models. He also stated that separation issues didn't extend through the years but was only an occurrence on the first shipment of bikes. That would be what... somewhere around 1984?

You can read his posts over on roadbikereview.com He's posted as "spokesniffer".

Some Specialized history

plonz 

I'm sure he'd appreciate the offer but he's already looking at turning the frame into an art piece. I'm sure he'll do it right just like the guy with the Spynergy ceiling fan.

It might also be worth noting that once the downube gave way, the remaining tubes all came loose. He says there's not an original angle left on the bike.

Lots of creative ideas shared here about how to re-bond the frame. For me, these are amusing but nothing I'd actually trust after seeing this actually happen. Not when clipped in over 10mph anyway.

BTW, he's looking for a higher-end 56cm vintage steel frame (leaning toward Italian) to move the parts to. Please PM if you know of something.

Be safe with those CF lugs

verktyg 

@Trakhak

The attached pictures show a cast aluminum bottom bracket from a 1990 Raleigh USA Team 753 Technium frame with oversize Reynolds 753 main tubes.

The "rings" around the joint between the lugs and tubes are cosmetic additions to conceal the adhesive filled gap. Both rings are cracked which seams to be common with those frames.

The Reynolds 753 straight gage tubes have a 0.6mm wall thickness plus an aluminum sleeve inside at the joints supposedly to stiffen the frame.

The reason that I bring this up is that a lot of the failures in the Raleigh "bonded" frames have been at the bottom bracket juncture.

Notice the small amount of surface contact area between the sockets in the BB and the tubes - see pictures.

Even with the down tube being slightly oversize plus the internal aluminum sleeve, the 0.6mm wall thickness is rather thin for a down tube. This could result in some flexing in the vertical plane from riding over rough pavements, hitting potholes and for some riders, jumping curbs.

Those kinds of stresses put adhesive bonds in shear where they're weakest - see last picture.

What I'm suggesting is that if the BB shells had a larger contact area via deeper sockets they would provide more contact are for bonding.

That's all moot now because these are 25+ year old frames, long out of production.

One last thing, we didn't sell kid's bikes. Occasionally an irate parent would drag in their teenager's 10 speed with the down tube pulled out of the head tube lug....

Their kid had been jumping curbs or BMXing with the bike! The give away was the forks were bent forward from the crown!

verktyg

Chas.

RobbieTunes

The rest of us are just bike geeks.

AlexCyclistRoch

Nothing that you couldn't fix with some tubular mastic glue.....

Johno59

Verktyg posted:

'Those kinds of stresses put adhesive bonds in shear where they're weakest - see last picture. '

Every batch of resin, carbon, prepreg etc is tested for bonding strength with a peel test and tensile strength with a shear test to a specification provided by the customer. There are thousands of specifications for hundreds of different carbon/resin matrix's depending on the end-user environment.

Rain, ambient temperature, humidity etc are never a problem. An aircraft can go from a 60 degree Celsius tarmac to minus 40 C in 15 minutes for 30 years and not suffer performance loss.

Planes, trains and automobiles operate in controlled environments under very strict rules and regulations - bicycles and potholes do not. A rider may weigh 100 lbs or 250 lbs, the pothole may be an inch deep or six inches deep, the rider maybe seated, standing on one pedal or both or none, travelling at 10 mph or 40 mph. They may have pulled up and cleared the front wheel but crunched the rear, then pitch-poled forward and smashed the front wheel at a very different angle etc. The specification to cover all of those variables is impossible to shape.

Any one of those scenarios could cause a pressure spike that exceeds the yield strength of the resin/carbon matrix. If that occurs one or more of the layers will shear and delaminate - 90 % of the time internally where the shear pressure is greatest. You won't even notice it visually and unless you are Andre Greipel you won't notice it mechanically, but because the component is monocoque by nature, the damage will slowly spread - regardless whether or not you hit another pothole.

Where I live the roads are terrible and my LBS owner calls older carbon bikes 'creakers'.

The solution if you must have more plastic in your life - don' t crash, never ride over a nasty pothole, house-brick, curb or other cyclist (I've done them all). Never, ever, ever lend your carbon bike to anyone and never buy one second-hand.

Chrome Molly

Failure of the aluminum lug. Seems the carbon/epoxy bonds were stronger than the lug itself. Once the lug cracked, the remaining "effective" glue surface was about a quarter of what the design had originally when the lug was sound. Hard to say if the lug and glue bond went in one fell swoop.

Considering how whippy these old carbon frames felt, lug failure is the likely outcome for most of them. The early lugged aluminum frames seem to fall in a somewhat similar way. Aluminum lugs vs cast steel offer different "cyclical points of failure". Brazing vs glue probably plays into things also but this particular example seems to have died due to the aluminum failure primarily.

RobbieTunes

Never had a problem with any of several lugged carbon frames, and yes, some are whippy, some more than others. I have bought every one second hand, because that's the reality of the situation. I definitely look at the bonds and look for cracks, but probably wouldn't recognize a warning sign if I saw one. Statistically, as time goes on, 80's tech would probably show its shortcomings if I bought enough old carbon frames.

Some just seemed a lot stronger than others, or maybe stiffer. The Trek Composite, Specialized Allez Epic, for example, seemed stronger than a Cadex, and the Cadex seemed stronger than the GT and Centurions. I have to admit, the confidence level on a carbon Ironman is somewhat different than that on a steel Ironman, descending Thunder Ridge with literally nothing to slow you down except air vs. sail area.

Had a Technium frame as well, and hit a dog at considerable speed. The bonds held fine, while the aluminum tubing crumpled right at the bonds. I doubt steel would have been much stronger at that speed, but adhesives have always amazed me, and there is such a huge gap between what you find in retail stores vs. what is used commercially.

In the (older) Kestrel seat tube failures I've seen, all kept their adhesive bonds while the inner aluminum sleeve cracked.

I think psychology plays a role, as some of us older folks grew up with steel and the transition to things that seem less strong, no matter the fact, is not a smooth one. I've never used an aluminum bat, and don't intend to. I know plenty of people who've never used a wooden bat. The local sound of a well-hit baseball off of an ash favorite is fading fast. I digress.

I have to say the only carbon bike I've ever had that seemed near bulletproof was a Merckx EMX-3. Wish I still had it. Others called it overbuilt. The rest, I've almost had to convince myself of their hardiness. Bridge builders often say anyone can overbuild a bridge, but it takes real know-how to build the right bridge for the right load. I think that's where carbon bikes are today; there is measurable data in so many ways, the bikes are tailored within parameters.

Lugged carbon just looks cool. I'd ride 'em until they fell apart, then find another one. They'll be gone soon enough. They are interesting projects, as well, just in a different way than steel. That being said, no one should have to ride as if their frame is going to fail, so I'm keeping in mind this thread and others when I decide to point my lugged carbon down some steep twisties with the potholes at the bottom. The back nine on the Dairyland Dare had such situations, and my white knuckle level would have definitely been higher.

jyl

Lugged carbon frames were made from the late 1970s (Lineseeker) until the late 1990s (maybe later, I dunno). Surely adhesive technology developed considerably in that period?

My lugged carbon bike is from the very end of that period. Vitus 997, circa about 1997, oval carbon tubes in aluminum lugs. It's a stiff frame, not noodly at all. I ride it without any concern.

qcpmsame 

Any comparisons to the still current carbon lugged, carbon tubed framesets? Calfee's and Colnago's models with carbon fiber tubes and carbon fiber lugs have been around a few years now.

Anyone know how these type frames are fairing in relation to failures of either the tubes (at the lug) or having a lug fail? Granted those are two top end bike models, if there are other examples in lower tier models please give any data about them too. I would be interested to know if these types of failures were limited to frames with CF tubes and alloy lugs. Any discussion or information is appreciated.

Bill

Trakhak

There's tailoring within parameters, and then there's the human propensity for taking shortcuts. An engineer I worked for who owned a bike shop for a while had had a summer job in college working on a crew building overpasses in a section of I-95. He said that some of the steel structural members had warped by the time they were ready to be used to reinforce the concrete supports for the overpasses, so the crew used cranes and cables to twist them into shape; once the concrete had set, they cut the cables. He said that he always avoided driving those sections of I-95; he called those overpasses "ticking time bombs."

Spaghetti Legs 

I have a Colnago E1 from 2005 which is a monocoque front triangle bonded to the rear triangle. I bought this used in late 2006 from possibly the sleaziest eBay seller I've ever encountered. It had a crack at one of the seat stay joints. There were several scrapes on the down tube but no other damage. I sent it to Calfee for a repair and have happily ridden it since as my #1 do everything bike despite it being slightly small for me. I'm finally replacing it now, not because anything is wrong with it but I like the ride of lugged carbon better and I want to try one that's actually the right size. Colnago EPS is on the way.

My lugged carbon experience is a '96 C40 still a wonderful bike - only problem is worn bottom bracket threading that required a creative solution , and a mid 2000's Alan cross frame that I couldn't recommend highly enough.

modelmartin

In 2011 I bought a '89 Raleigh Technium PRE aluminum main tubes with steel lugs, triangle and fork. It was $140.00!! I have upgraded all the mechanicals but still have the frame and fork. It comes in at about 22-23 pounds. I have ridden it over 10,000 miles since and it is a fantastic bike. I also have a 92 or so Raleigh SP1000 Technium style frame with Titanium tubes, aluminum lugs and 531 forks and rear triangle. It was a NOS frame and I have only put about 500 miles on it this year. Both bikes seem totally fine. I am not a real strong rider but can not imagine what it takes to make these frames fail aside from someone doing big jumps or running them into walls!

Johno59

Robbie Tunes wrote:
'I think psychology plays a role, as some of us older folks grew up with steel and the transition to things that seem less strong, no matter the fact, is not a smooth one. I've never used an aluminum bat, and don't intend to. I know plenty of people who've never used a wooden bat. The local sound of a well-hit baseball off of an ash favorite is fading fast. I digress. '

Carbon fiber is superior in every way except in temperatures over 100 degrees C and some chemicals - neither much of a concern for cyclists. It has amazing mechanical properties that metal can't even get near - as long as you remain within its tensile yield strength. This is considerable, but unlike damaged metal it can conceal the damage.

The main advantage of steel is comfort, price and longevity.

There is a an unanswered question as to carbon composite longevity and how UV waves can accelerate the loss of performance. Aerospace draws the line at 30 years. I doubt this will move much as most resins have not changed much in chemical composition over the last 20 years. It is the weaving of the fibers and the fabrication that has changed dramatically.

In other words if you don't damage the bike you won't have a problem - unfortunately outside a organized race environment this can be a difficult task to accomplish for the average keen cyclist.

gaucho777 

FWIW, when I had my LOOK KG86 frame repaired by Frank the Welder (replaced rear dropout), he used 3M DP460 epoxy for the repair.

He also had some interesting comments on the process of extracting the broken dropout prior to applying the epoxy to the replacement dropout. Perhaps these comments will be of some use to others down the road. For clarification, I sent him a complete frame with damaged rear dropout, and a second ("new") dropout cut out at the stays from another donor frame. Part of the process he describes below is the removal of the donor dropout from the other frame:





After:

willydstyle

As a polymer chemist I would not trust carbon that had been heated to 400F as it could increase crosslinking in the epoxy matrix and cause embrittlement.

gaucho777 

@willydstyle, Point taken, though to be clear, in this case the initial extraction was done on a donor dropout. When the broken dropout was extracted from the frame, there were some efforts made to keep the carbon stay end cool, and you can see there was almost no discoloration of the repaired frame compared to the stays originally attached to the donor dropout. Also, the 400F temp was the temp of metal dropout, not necessarily the carbon. As someone who is not a scientist, I don't know how much heat would have transferred from the heated dropout through the epoxy and to the carbon itself, but I imagine it never approached 400F (but what do I know?). So for no issues, but I do plan to inspect this frame more closely and regularly than my steel frames.

jyl

Also, how many times have anyone seen any frame fail at the lower stay end near the dropout? And modern race bikes use incredibly narrow stays, like pencil thickness there.

Johno59

One of our niche customer high-end specification is a resin/carbon/honeycomb matrix for the inside of engine cowlings. If the inside surface reaches anywhere near 180 deg C (356 deg F) you are flying uninsured.

RobbieTunes

Now I feel better.

RobbieTunes

All of which means Frank is a master, a genius, and one heck of a nice guy. Thanks for the great post.

RobbieTunes

At least once, 2013 Felt. Didn't "fail" but it looks a bit crumbly right at the RD hangar.

RobbieTunes

"Pasta lower limbs" mentioned lugged Colnago's, and I can't see how they'd design and market anything if the confidence level was not high. Having owned a carbon lugged 2004 Cinelli, I second his remarks. I'm confident that if Andreas Cinelli and Ernesto Colnago think it's OK, I probably should, too.

It's interesting to note that there was no wide-spread embracing of the older-style lugged carbon frames, even when they were competing and winning on the Tour and in the Ironman.... The industry didn't do a big old makeover like it did with aluminum for a while.

Perhaps we need to ask those in charge before we lose their wisdom and words permanently? Would be a good book.

A BF member did his masters thesis on vintage lugged carbon frames, and I'll see if I can get ahold of him and get a copy.

Regarding carbon fiber in general, I have a particular car I like, and I often think about what fun it would be if all the body panels were CF instead of steel. I've seen some local gearheads who are into aero and weight vs. displacement do some amazing things with those Mitsubishi Eclipse coupes, using almost all CF body panels and a little bit of boost. Holy cow those are quick.

bulldog1935

glue can only last so long (that includes the resins that hold modern and not-so-new carbon fiber together)