JunkYardBike

Just acquired a 1987 Raleigh Technium with 6061 aluminum main tubes bonded to steel lugs and steel rear triangle.

Here is what is happening at the bond between the downtube and headlug:




Is this the indication of a more serious problem? Or are those bands cosmetic covers over the joints? There doesn't appear to be cracking or fracturing anywhere else along that joint, or at any other joint on the bike.

Any thoughts?

TallRider

I don't know enough about the Techium to answer. But if you don't figure out any useful info about the crack, then you should not ride the bike. Only ride it if you can confirm that it's safe.
"The bike is dangerous" should be your default hypothesis here.

Btw, the point of the crack could be indicative of a crash - on lugged steel frames it's common for the tube to buckle slightly just below the lug on the underside of the down-tube.

erader

i wouldn't ride it. looks like you are getting fair warning. i've had a few bonded frames (a technium too) and that looks like it's debonding to me.

ed rader

Alloy Addict

I'm not sure what to say about the bonds. Is that the only spot that's doing that? If I already owned it and was just worried, I think I would pick away at that ring a little to determine if it is just a cover to make the joint look clean. If so I would inspect the naked joint for gaps or bends or sproings or whatever. Even after that you still don't know for sure. Clint Eastwood saying, "Do you feel lucky?" seems to pop into my head righat about now.

I had a 1987 Technium city bike, that was my first, new, bikestore bike. It had a horrible Maillard drum brake that no bike shop in town could get to work well. I snapped a pedal spindle one day while riding down the road, *ping* no pedal. Then the handlebars broke just as I started up a hill. I literally had handlebars for a brief second. After I replaced the bars I didn't have any trouble with it, except the cruddy drum brake. Out of curiosity, which model is yours? Does it have internal cable routing?

HillRider

If you look closely at the photos, there appears to be some cracks in the paint on the downtube side of the joint also. None of this is a good thing.

Frankly, if it were my bike it would be headed for the scrap heap right away.

JunkYardBike

Tried to determine that with a thread on C&V. One member thinks it's probably the Prestige model, and yes, it has the internal cable routing.

I offered it free on the C&V thread - good thing the sole interested party turned it down. The frame is too small for me, so I was thinking of trying to sell it for a few bucks, but I wanted to make sure I wasn't selling a damaged frame. Was looking for a definitive "it's just cosmetic," but since the consensus is that it could be serious, I'll refrain from selling. But, darn, it was perfect for marketing as a ss conversion to the NYC crowd!

Thanks for the advice everyone.

leob1

+1

Can you determine if the tube and the lug are true?
I would hang it on the wall.

JunkYardBike

Definite possibility. The fork is not original, which could be a telltale sign. Bars and stem are not original, and neither are the brifters. Wheels are not original (could be an upgrade to 7-spd to match the brifters), and the original pedals are gone. All of these areas could have sustained damage in a crash.

However, there doesn't appear to be any damage to the rest of the frame and there is no serious road rash anywhere on it.

You know, it actually looks as if the tube and lug at his joint are incongruous by maybe a fraction of a millimeter, in the direction away from the crack. This is also true of the bond between the downtube and bottom bracket lug, though there is no evidence of cracking there. And the closer I looked at the lug, there does appear to be a slight indentation on it, opposite the cracking, as if the tube flexed in that direction. Also, there appear to be wrinkles in the lug, as if it were stressed in some way.

On the other hand, this all may simply be manufacturing imperfections. I really have nothing to compare it to.

kgatwork

The ring is not the main bond joint. The steel lug inserted inside the main tubes is where the main bonding surfaces are held together. Does the frame flex alot? That could just be cracked paint.

Retro Grouch 

That's what it sounds and looks like to me. It's an old Technium frame so your monitary loss is minimal unless you start pouring more money into it. If it was my bike that frame would be dumpster fodder.

Blender

I posted a Raleigh Technium Brochure on the Framebuilders forum.
Have a look

https://www.bikeforums.net/framebuilders/215343-epoxy-bonding.html

JunkYardBike

So it appears that band is simply a decorative piece used to make the overlap look more finished? That brochure doesn't make mention of it as having any structural purpose.

I can't really tell if the frame has flex as it is now completely disassembled.

jerrymcdougal

Could it just be from putting the bike over a bike rack? Thats where the bar on a bike rack will contact the frame. Just an idea.

Blender

I bought one new in 87 and it is still going strong. The only original parts are seatpost (I think) , stem FRAME and kickstand.
I like the ride from Day one.
The Technium seems to get thrown under the bus with other Bonded frames but in fact they hold up well.
I once found one along the highway that looked like it fell off sa car. The bonds were good, the rest was bad

operator

Chip the paint away and find out.

TallRider

Yes, very good idea. If the ring is simply comsmetic, this won't hurt. If it's not just cosmetic, well, it's started to go anyway, and nothing lost by finding out what things look like underneath.

Trakhak

Use a micrometer to measure the diameter of the top tube and the down tube vertically and horizontally near the head tube and at various points along the tubes. If the cracked rings at the bonding joint are evidence of a front-end collision, the horizontal measurements near the head tube should be larger than the corresponding vertical measurements, since those tubes get ovalized in front-end impacts.

This works for conventional steel frames. Technium frames are probably somewhat stronger, what with having what amounts to internal steel lugs several inches in length, so you should still be suspicious of significant damage even if the tubes aren't measurably ovalized.

Another quick check for a bent top or down tube: use a straightedge along the tube. A rise a few inches out from the head tube usually means that the frame took a good front-end smack at some point.