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Ruined Cinelli Stem ??

Old 08-14-21, 12:01 PM
  #1  
sdn40
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Ruined Cinelli Stem ??

I think I know why it was done - but sad. Seems like a rare stem too.



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Old 08-14-21, 12:10 PM
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Originally Posted by sdn40 View Post
I think I know why it was done - but sad. Seems like a rare stem too.



Yep, bummer but those are POS when the wedge breaks. I would find a lower profile button head bolt and grind it down so it doesn't stick out so much. Maybe even use a small smear of super glue or JB for good measure and probably not ride it too far from home.
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Old 08-14-21, 12:31 PM
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Yep - I was thinking set screw
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Old 08-14-21, 12:33 PM
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-----

good candidate for inclusion in bulgie 's gallery of failed and broken components -

​​​​​​https://bulgier.net/pics/bike/Broken


-----
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Old 08-14-21, 04:45 PM
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I have seen similar “augmented” 1R stems.
desperate moves.
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Old 08-14-21, 05:07 PM
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I have never used these brazing rods yet, but if your considering filing the hole it might be worth a try...

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Old 08-14-21, 07:45 PM
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Looks like it's cracking. I had a 1/R break on me, it's really exciting. Actually rode it home though.
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Old 08-14-21, 09:23 PM
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.
...when a bicycle component is "rare", a part of me always asks, "Why ?"
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Old 08-15-21, 07:37 AM
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Ok, I'm gonna say it: I would never use that stem. I'd also be on the fence about using those bars.
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Old 08-15-21, 11:04 AM
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Originally Posted by onyerleft View Post
My guess is that the stem suffered damage when somebody tried to jam in handlebars of the wrong dimension.
Those stems are well known for the internal wedge cracking and breaking all on their own for poor design, overtightening, lack of proper lube, etc.

These won't tolerate a much bigger bar and I don't think that would break the wedge, seems to me like it might help with keeping the wedge intact.

Too small would more likely be the culprit I think.
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Old 08-15-21, 11:44 AM
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Originally Posted by zandoval View Post
I have never used these brazing rods yet, but if your considering filing the hole it might be worth a try...

https://youtu.be/CCycms8wVC4
I would not do this. I have used these rods and, while the repair is strong enough for some applications (rods like this are especially popular for HVAC refrigerant tube work), I would not trust it for a stem clamp. Depending on the alloy, it may change the grain of the rest of the stem clamp area when you heat it up, and the composition of the surrounding area when you add this stuff. You also don't know the alloy (unless someone here can enlighten us). These rods work well on series 5059 aluminum, but you don't know what your stem is made of. It could be the non-weldable, but common-in-forged-components 2014 for all you know. I would also not TIG weld it for the same reason, even though I can, and have, TIG welded on stems (of known alloy) in the past.
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Old 08-16-21, 04:13 AM
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Say goodbye to it. It's fugly and dangerous in it's present condition.
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Old 08-16-21, 06:11 AM
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Originally Posted by scarlson View Post
I have used these rods and, while the repair is strong enough for some applications (rods like this are especially popular for HVAC refrigerant tube work), I would not trust it for a stem clamp..
If you are familiar with the stem, 1R, would you use it to "glue" the wedge back together?

I am not convinced that the broken parts of the stem contribute that much to the clamping force. What is critical in this design are the raised parts on both the bar and the stem. I have a few with one having a broken wedge. They all work well for me with the proper lube of the wedge ramp and associated parts. My favorite is the XA in terms of appearance. The 1A is just plain practical.

I am willing to be flamed here but I am trying out a 26 bar in a 26.4 1R. So far, so good in the testing. I tried to shim with beer can stock but it was too slippery. I have read all the warnings from all of you over multiple threads so you don't need to repeat how stupid I am to do this nor the consequences. I get it. The bar is about to be replaced anyway with a 65-40.

I have noticed that there is always a gap on the wedge side, even with the correct bar diameter. The diameter of the 1R is around 26.7 on the one stem I measured.
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Old 08-16-21, 11:01 AM
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Originally Posted by SJX426 View Post
If you are familiar with the stem, 1R, would you use it to "glue" the wedge back together?
Yeah, I have a 1R in my bin of curiosities so I know how they go together. I think a crummy weld would be ok because the wedge is under compression. If you could get that rod to work, of course. Its performance is pretty dependent on the base metal you're welding, and we have no idea what exactly that wedge is made of. So, try it if you've got nothing to lose. I don't think it would cause a catastrophic failure of the wedge or loss of control of the bike. More likely, the wedge would crumble on tightening or gradually come loose, requiring more tightenings until it fails.
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Old 08-16-21, 11:41 AM
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@scarlson - I don't have one of those rods but if it were a possibility.....

The wedge is a casting so it is not as strong as other mfg methods. I think they break because of a bending force or poor installation. The break is often on the perimeter. The size helps address surface contact with the bar and helps with preventing bar rotation.
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Old 08-16-21, 12:02 PM
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Originally Posted by merziac View Post
Those stems are well known for the internal wedge cracking and breaking all on their own for poor design, overtightening, lack of proper lube, etc.

These won't tolerate a much bigger bar and I don't think that would break the wedge, seems to me like it might help with keeping the wedge intact.

Too small would more likely be the culprit I think.
Could be they could no longer find the appropriate wedge.
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Old 08-16-21, 12:48 PM
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Dental Insurance

Originally Posted by SJX426 View Post

I am not convinced that the broken parts of the stem contribute that much to the clamping force. What is critical in this design are the raised parts on both the bar and the stem. I have a few with one having a broken wedge. They all work well for me with the proper lube of the wedge ramp and associated parts. My favorite is the XA in terms of appearance. The 1A is just plain practical.

I am willing to be flamed here but I am trying out a 26 bar in a 26.4 1R. So far, so good in the testing. I tried to shim with beer can stock but it was too slippery. I have read all the warnings from all of you over multiple threads so you don't need to repeat how stupid I am to do this nor the consequences. I get it. The bar is about to be replaced anyway with a 65-40.

I have noticed that there is always a gap on the wedge side, even with the correct bar diameter. The diameter of the 1R is around 26.7 on the one stem I measured.
Warning to others besides quoted member who may consider using an undersized bar :

This is a Cinelli 1a stem not a 1r but it's an example of what can happen when clamping down on an undersized bar:




BITD, in the early 70's when we were young and dumb, we sold a lot of French bikes at our shop. French 22.0mm stems like Cinelli 1a and 3TTT Record where hard to come by, matching bars too...

Back then there were very few sources for bikies to get good info so everything was learning by trial and error.

We used the 25.0mm or 25.4mm bars alloy that came with the bikes and clamped down on them. Those quality stems broke while clamping down on the undersized bars at least 20% of the time. We quickly learned our lesson after breaking several expensive, hard to get 22.0mm stems.

PSA:

Dental insurance is expensive, uninsured dental costs far more so than the cost of an old bicycle stem!!! Then there's plastic surgery, ortho MDs and worse...

Unlike steel, aluminum has a very low bendability rate. It has in general 1/3rd the strength of steel. That's why all of the recommendations to not try to spread to fit or clamp down on incorrect sized bars. You can only bend aluminum a small amount before excess stress and cracks form.

REMEMBER the call of the Darwin Award Candidates: HEY! WATCH THIS!!!

It never ceases to amaze me that C&V folks will spend hundreds of dollars on components for their bikes and then cheap out on the weakest, most critical elements - the bars and stems???

The Cinelli 1r and XA stems have known design flaws. They're 25 to 40 year old components and should be retired at the slightest sign of a problem. Same with any other stem or bars.

If you acquired them used, you have no idea what a former owner did with them.

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Old 08-16-21, 12:59 PM
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What is the issue with the 1r stems? I've used several without problems.

My main problem with them is that mine aren't labeled with their clamp diameter and I never thought to mark them myself before putting them in the parts bin.

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Old 08-16-21, 01:28 PM
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Originally Posted by himespau View Post
Could be they could no longer find the appropriate wedge.
Absolutely, most often now days you have to buy a stem to get a wedge, then you have two useless stems if/when that wedge crumbles.

I recently and reluctantly bought one of these as it was Merckx panto, its wedge was cracked. I found a stem with a good wedge on here for a good price and then found another good wedge on efbay for an ok price as well.

So now, I have two complete stems with good wedges that I never plan to rely on despite being heavily invested.

These are POS design and material of the wedge in my mind and I'm going to research smoothing all the sharp edges on the wedge for stress relief. Also seems to me that one could add an abrasive layer to the grooved side of the wedge to lessen the torque needed, possibly reinforce by epoxying it and keep it from cracking.
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Old 08-16-21, 01:41 PM
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Broken Cinelli 1R and XA Stems

Originally Posted by himespau View Post
What is the issue with the 1r stems? I've used several without problems.

My main problem with them is that mine aren't labeled with their clamp diameter and I never thought to mark them myself before putting them in the parts bin.
Answer from esteemed member T-Mar back in 2009:

https://www.bikeforums.net/10030466-post15.html



What I suggested in my post above was stems and or bars with any kind of problem should be taken out of service or better yet discarded so that some unsuspecting soul in the future couldn't put them back to use...

That very small cross section of metal is all that keeps the bars and stem connected!

The human skull is like a cantaloupe - think about it...

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Old 08-16-21, 03:05 PM
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@verktyg - I do appreciate the your note. I have not seen the 1R break. The 1A break with an under sized bar is not surprising at all. I would also expect the XA to break in a similar way with an undersized bar.

Are the recorded breaks of the XA due to undersized bars?
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Old 08-16-21, 04:21 PM
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Originally Posted by SJX426 View Post
@verktyg - I do appreciate the your note. I have not seen the 1R break. The 1A break with an under sized bar is not surprising at all. I would also expect the XA to break in a similar way with an undersized bar.
Are the recorded breaks of the XA due to undersized bars?
Both the 1r and XA stems were produced in 26.0mm and 26.4mm diameters. There are no bar diameter markings on the stems. Since many of these stems are old and used, no telling what a previous owner did with them.

The 1r stems were introduced in 1973 so there are some that are almost 50 years old out there!

In 1978 the logo on the plastic plate switched to the "winged C".

Here's a breakdown of the 1r wedge and parts... a picture is worth....



Cinelli Time Line up into the early 80's. No mention of the XA stems. Scroll to the bottom of the page for info on stems.

Velo-Retro: Cinelli Timeline

The XA stems probably broke in the same manner in the 1a stems - primarily from clamping down on an undersized bar.

Opening a bar clamp to fit a larger bar whether it was used with an undersize bar or to fit a 26mm stem to a 26.4mm bar is asking for trouble. If the stem doesn't crack or break during assembly, there's no telling when it could fail catastrophically!

Here's a 26mm 3TTT stem that was probably clamped down on an undersize bar. This is another place where this style of stem can fail.




So... my advice is to thoroughly inspect any older stem and bars before installing them and to periodically check them too. Any bars or stem with any sign of damage should not be used.

Old saying: "Don't be so cheap, you wont be so rich!"

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Old 08-16-21, 04:30 PM
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Forgive my ignorance, but:

Does anyone sell replacement wedges for these? Is there a lot of demand?

How many do you think I could sell, just on bikeforums, if I made some?

It wouldn't be too terrible to CNC mill, but my queue is pretty long these days.
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Old 08-16-21, 05:02 PM
  #24  
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Originally Posted by scarlson View Post
Forgive my ignorance, but:

Does anyone sell replacement wedges for these? Is there a lot of demand?

How many do you think I could sell, just on bikeforums, if I made some?

It wouldn't be too terrible to CNC mill, but my queue is pretty long these days.
No replacements that I know of, they show up on efbay but are somewhat cost prohibitive, embarrassed to say I bought one recently and paid what I paid for a complete stem with a good wedge here that was a good deal.

I'd be all for it and would gladly pay what I paid for a crappy one but can't imagine it would be worth the time.

These stock disposable ones seem to be maybe only a step above pot metal.
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Old 08-16-21, 08:11 PM
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The wedges are a low cost casting, based on the cross section of the break. Given that they only experience force in compression, it is not a bad choice, just not a great one.

Cinelli1RClamp on Flickr

Although there is a radius from the ramped feature to the curved surface, there is not a more gradual thinning of the curved surface from the ramp feature. This is due to the feature of the opening of the stem where the ramp fits. So the unsupported surface is a long lever that does not have reinforcement. It won't bend like a diving board and breaks.
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