SL67

I got a Nishiki Altron 7000 with cracked weld (1/4 inch long). The material of the frame is aluminum 7003. I ride the bike occasionally - only pavement, no gravel or trails. I check the crack frequently and as far as I see it's not propagating.
What's the odds that the headtube would tear off like... you know... in a moment? Is it very dangerous to ride the bike even if the crack is not propagating?
Yes, I know that it's cheap to replace the frame. The problem is I like the frame so much - it fits me perfectly.
Using the scale of 1 to 10 please describe the danger I expose myself to.

bboti

I think, it is ok, I would say 2

10 Wheels

ONE...nice color

Bike tinker man

I would be temped to remove the paint in that area, as you can only see 1/4" crack, you could go to an engineering shop & ask them or buy some crack penetrate, the one I used to use was like a dark red dye, that will really show up how big the problem is.

The normal engineering way to stop a crack migrating is to drill very small holes at each end.

GOv

Maybe when i was younger i would of been prepared to be careless but at my age, i like my face & teeth the way they are. On a scale with just looking at pic, i would give it at least a 6 on what i see (the unknown is scary).

Would you let your mother or kid ride it and take the chance it would be ok? Not me!

But if it was a frame i really (really) liked, then i would probably consider on having it pro repaired and repainted.

easyupbug 

If you cruise around your neighborhood at 10 MPH I think the likelihood of catastrophic failure (not catching severe cracking) and the consequence of that failure are both low. If you bomb down a decline at 30 MPH, likelihood and consequence are both high (face plant).
Stop drilling the crack (hole at each end) might help remove stress risers, but I would think only a full strip and weld repair would reduce the risk to something I would want to ride.

HillRider

First, are you sure it's really a crack in the frame metal, not just the paint? Second, if it really is a crack in the metal, I'd replace it. Aluminum can be pretty unforgiving when it fails.

Yeah it "fits you perfectly" but there have to be dozens of other frames that can be set up to match it. It's not that difficult.

dsbrantjr

This is the procedure for cracks in sheet metal, not sure it would work with a failed weld or braze fillet.

OshkoshBiker

The paint would need to be removed from the entire weld circumference and the use of a dye penetrant like they use on aircraft parts to inspect for cracks. This is going to be difficult if the weld is not entirely smooth. The end result may also be inconclusive.

Stop drilling will probably cause more damage than it's worth on a weld.

If the crack really exists and it is not just a crack in the paint, it is time for a new frame. Any repair will be impractical for most due to expense.

Bike Gremlin

The problem with metal is it doesn't give warnings. It can crack suddenly. Unlike wood.

I wouldn't risk it.

fietsbob

Ready to remove the paint to inspect the bare metal?

Perhaps a frame builder used to working in welded aluminum,
can add another pass, more aluminum, to that weld joint, leave the bead this time.. rather than smoothing it,

then you get it repainted

corrado33

Really? I always thought metal failed pretty slowly and obviously. I've seen many more "oh my headset feels loose and I can't get it tight" than "oh my headtube cracked off and I crashed spectacturarily."

I'd ride the bike in the OP.

HillRider

Steel can, and usually does, fail rather slowly and gives some warning. Aluminum tends to fail rather suddenly.

kevindsingleton 

Maybe we don't hear those stories because those people don't survive the asplosion!

I'd ride it, too. I probably never would have noticed that "crack".

SkyDog75

If you think about how forces are carried by the frame, the top tube is under compression when the bike's carrying weight. I might not go bombing down mountain descents on this bike, but I don't think there's too much danger to riding it casually. Just keep checking the crack regularly.

corrado33

Yeah that's probably true. Luckily metal has enough strength in all directions to sometimes prevent a serious crash in the event of a catastrophic failure. Most failed metal frames I've seen have a crack or break along a single tube/stay. I just had an old salsa frame come in yesterday that had "scandium" chainstays and one had sheared off at the chainstay. Guy said he didn't crash it just felt like something was wrong.

DiabloScott

I submit that it's a 1 right now, and will eventually become a 10 if you keep riding it. The question is how many rides that'll be.

If it were me and this were a neighborhood/trail bike, I'd keep riding it and inspect it frequently - and after every ride I'd try to flex it and make the crack get bigger - if I can't make the crack worse when I'm trying to, it probably won't get worse with normal use. I'd be especially aware of unusual feedback during steering and accelerating.

If this were my long distance or hill climbing bike, I'd have a new frame pretty soon.

Homebrew01

I would ride it, and keep checking to see if it gets worse. If it increases, scrap the frame.

bradtx

SL67, It may simply be the paint where there was a void between the weld and the metal. Could be a tube fracture, either way you're going to need to remove the paint to see. I've heard that air hardened 700X aluminum is more forgiving of a weld, by a professional of course, than 60XX aluminum that is heat treated after being welded, a point to explore if needed.

Brad

speedy25

A friend of mine had a recall on the aluminum swingarm of his motorcycle. He thought similar to many of you- "I'll just watch it and get it fixed when it shows a problem. It failed catastrophically. He took a trip to the hospital. Advice about AL failing suddenly around a defect is correct. It may not be worth just taking a chance and seeing if it gets worse.

-SP

Delmarva

The o.p. should determine if it is a crack in metal or only paint.

davidad

In the shipyard we drilled 1" holes in 2" plate to police cracks.

davidad

If you inspect it every ride you should be ok. Know that Al. has a definite fatigue life.

mrv 

I bought a complete CANNONDALE bike from a friend who thought the head tube was cracked. I moved all the parts to a GUNNAR Rockhound after painting it.
I stripped the paint on the CANNONDALE and polished the frame and found no crack. It's subsequently been powder coated and is waiting for me to build it back up with a rigid fork.

I'm with the folks who think it's probably cracked paint, and if you want to avoid a face plant due to an unpredictable catastrophic failure, you have to look under the paint.

Hope it all works out for the best!

project album: https://goo.gl/photos/om6FUVuHkAqnqpR18
head tube: https://goo.gl/photos/4KWjHZkGEu5ByN5N8

xiaoman1 

I'm with those that say clean the paint to verify if it is a crack....nothing to loose as the paint is not matching anyway and removing a small amount for security and piece of mind is worth a lot.
If it is a crack have it repaired, if not use touch up paint......not worth worrying about every time you go out...do it once and know for sure.
JM2C's Ben