Njord Noatun

The expander wedge in my Cinelli 1R quill stem has cracked, and I am in the process of sourcing a replacement.

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When I put it back together, is there anything I can do to reduce the risk of this happening again (obv, I won't be tightening the bolt like my life depended on it)?

3alarmer 

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...it's a very common issue, and appears to be related to a bad design and execution of it. The little teeth thingies on the side you don't show flatten after you tighten it, and don't grip as well. So when you tighen it more than once or twice, often you need to tighten it more than is healthy for the little wedge thing. Sourcing a replacement is often difficult for this reason as well. If you buy one used, it often comes with the teeth a little bit flattened.

unworthy1

I think it's a design flaw and the cast steel part (as choice of mfg.) only compounds that.
I have a complete 1R stem if you want to buy the big enchilada and cannibalize as you wish, PM me.
It's complete, 90mm and has the "Flying C logo" cap; condition is very good.
I do not choose to part this out per my own "general principals".
A new owner can do as he/she will with it.
As for preventative maintenance I think just grease all moving parts generously and cross your fingers!

repechage

Make sure the bar is fresh at the clamp area
that broken part looks pretty gnarly.
I would make sure high compression grease was on that wedge interface.

there were all kinds of arguments way back regarding greasing the bar to the stem surfaces.
today, I might consider friction paste.
way back those who were in the dry assemble camp also had creaking bars.

merziac

These are on my radar and I saw a wedge recently for $39 somewhere, maybe efbay.

I think a radiusing of the serrated edges of the ridges could help, may diminish the "bite" though so....

I got a Merckx panto one that the wedge is broken on, bought a whole stem to get a wedge.

Jmpierce

I replaced that piece on a stem for one of my bikes. Link to the part.

https://www.ebay.com/itm/Cinelli-13-...item218a9e3142

merziac

That link takes you to a bolt, not the wedge.

I think that's the same seller I saw.

Jmpierce

Whoops.

https://www.ebay.com/itm/38419257242...sAAOSwuBhgsZjj

3alarmer 

https://www.ebay.com/itm/29426930793...oAAOSww6pg6I3z

3alarmer 

https://www.ebay.com/itm/31355902664...gAAMXQnYJQ~Y0i

repechage

Pricey little parts they are now.

3alarmer 

...testify. It got me to thinking that maybe, back when they were making them, the wedge was considered a disposable item, and places would stock them new for something a little closer to what it must cost to make them. I'm surprised nobody in eastern Europe has tumbled to this market, and started machining new ones. It wouldn't be that hard to make, if you set up and made a lot of them.

unworthy1

I immediately thought: "is somebody 3D-printing these"? With the metal-infused stuff that's supposed to be on the market for the really high-end 3D machines, but would not be surprised if that material could be even more crack-prone than the original.
So, any engineers, or better yet metal-fabricators, think these could be CNC-made of billet aluminum to be a better product than the OEM?
What about 3D-printed wax forms and investment-casting: or is that what Cinelli did to make these in the first place?
Would some different (cast-able) alloy hold up better than what Cinelli used?

Chombi1 

My experience with the R1s had been, you really have to crank down on the clamping bolt to get the clamping wedge tight enough against the bar, to keep the handlebar from spinning in the mounting hole, every time you apply the brakes just moderately....
I'm really not surprised by the damage on that stems wedge.

repechage

Porsche is making 3D printed pistons now for a production model. I think 3D printing could create a part with less stress risers.
now, having written that, who wants to take on the liability?