3ttt Record Stem usable or not?
 

I just acquired this from fellow forum member #NOLA Sekai 4K (Martin) in a very good transaction all around.

My cleanup and polishing (I generally like all things shiny when they can be) brought a crack at rear of the clamp area to light. I did not see it until cleanup, not sure it was really visible till then and I know it surprised Martin.

If you look at the crack it could seem to have resulted from the backer nut being press-fit into the body?

I felt like it had been there since manufacture…stem had obviously been ridden and if there from beginning might be ok.

Martin suggested getting on here and asking opinions. Please opinionate!


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Okay ....picture this ....you're riding down a hill rather quickly, and suddenly you lose the ability to steer or control your bicycle ....what's the worst that could happen ?

I tend to minimize dings dents and cracks...

That’s one I would retire though I don’t think the complete crack through would be likely. If it cracked enough to loosen the bars, that might be a bit problematic.

Not a good place to have any stress cracks...... Unfortunately, that stem is most likely toast.....:(

I have been using a Cinelli 1A stem with such a crack for years on my Vitus 979. My dad used it before me. He didn't even know it was cracked! I don't really see how this could cause the stem to loosen, much less fail catastrophically. Think about it - it's already cracked in to the bolt hole, which is basically a keyhole on the end of a crack - which is what you're supposed to do to cracked metal parts to keep the crack from propagating. The way I see it, the crack has gone as far as it can go, and you are safe from further progression.

But I have a hunch that I'll be in the minority on this one.

If you value all the parts that make your face recognizable to your friends, family, and co-workers, bin that stem.

As @jdawginsc points out, if the crack gets big enough to allow the bars to rotate - at exactly the wrong time, say, while braking hard downhill into a turn - very bad things can happen.

DD

Yea, I agree that it is not worth the risk. When I climb, I use the handlebars a lot for pulling on whiles I push with my feet in the pedals. I have not had a failure but I would think it would fail with a crack that size.

Nope, you're wrong, 'cuz I agree.

edit... I have seen several 3ttt stems that had failed rather catastrophically, but it was not this model, and not this failure. This one, I think, will get a little worse before it gets a lot worse.

Do you have a picture with the clamp bolt removed that shows how deep the crack is? Is there something super special about the stem, like, it was made of unobtainium? If not, why not just source a replacement?

The rear press-fit splined nut does not remove for a clearer photo. Nothing I could ever capture in a photo, but you can tell the crack does seem go through the rear below the nut but tapers quickly to not travel all the way. Looking inside it cannot be seen extending past that press fit nut so it feathers out on the surface…

This comment showed up on velobase in 2014 by an “s barber” :There’s an unrelated comment above that by a wolfram verktyg… there is a user here named Verktyg also! Probably same?

I would not trust that stem for a single ride. If it fails, utterly, and it will, your handlebar will become darn near useless. Get rid of the stem and get a new another one - they are not that expensive!

The only stem I've had fail was a TTT stem, and that's where it failed. I don't know if I had been riding it cracked; I was on a loaded tour, stopped for a rest, wind blew the bike over, and when I picked it up, the handlebar fell off.

I'd never use a cracked fork, stem or handlebar. The chances of them breaking might be very small, but if it happens it could be ugly.

Bro.. that’s cracked cracked.

There are so many stems that don’t have cracks. Why take a chance?

Just for fun ....why not put the phone number of the nearest maxillofacial surgeon on your speed dial ?

Nice pics! How much did that phone/camera set you back?

At some point the bars will loosen. I think its time for retirement. And a torque wrench.
The bars will loosen at a point when you don't want them to, like hour(s) from home.

In my opinion, if its going to fail it will fail at the worst time possible. the fact that it has cracked at all would indicate that an importantant part of its structural 'integrity' has been compremised. Ask yourself this question 'would i fit this part onto my favorite childs favorite bike, knowing it has a crack in it'? and there in lies your answer...

Thanks all. This is like group therapy. I have decided not to use the stem as it is.

@rhm and I can fight over it!

Can you explain where exactly the crack on yours ran? Inquiring minds and whatnot.

It is probably 2% chance it will fail. If your luck is anything close to mine, I'd be the 2%...it's no fun riding with doubt in the back of your head...

Response to above. There are plenty of photos above that will show the crack location.

And also to share that the seller NOLA Sekai 4K (Martin) is a great guy to work with!

Yes, I saw the pictures. But I want to know where the stem cracked that caused the handlebars to come off. Your crack can't really cause that at the moment, even if it goes clear through to the bolt hole. I want to know where hypothetical further cracks might start, if JohnDThompson might care to tell us how it looked after the bars came off on his tour. Perhaps the crack he experienced started someplace else.

Interestingly, it is known that the Cinelli 1E stem, which was designed to have a front-facing reflector bolted on the back, had a tendency to develop a crack similar to the one you show here, if the reflector was removed, because the tapered hole in the backside was not reamed large enough to accommodate the increased depth/diameter of the knurled nut sans reflector. Yet another way CPSC ruined changed things in the '70s.
My 1A with a similar crack to yours does, indeed, have an aftermarket nut - one of those Arnold Industries ultralightweight jobs. I think that's why mine cracked. It sounds an awful lot like the "non-critical" cracks mentioned by S. Barber on Velobase. Still riding it though - I'll post a picture tomorrow as the capstone of my dissenting opinion, and then I will shut up about it...