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I need some shims for a 25.4mm NSBikes Proof bar into a stubby 35mm long 31.8mm clamping alu stem with a 50mm wide clamping area. Most alu shims are 41/42/43mm wide. Using two sets brings the weight up about 70/80g so I started searching
Found these 60mm wide Fourier CF shims with a claimed weight of 24g.
https://www.fouriers-bike.com/en/news/99646866.html
Their sales bumf says:
we found through our vibration testing machine that the carbon shim significantly reduces riding vibrations due to the natural riding properties of carbon
Is this some sort of snake oil? Or lack of independent testing? I need these shims to do what needs to be done, but I'm dubious as to the claims.
Struggling to see the mechanism by which vibrations can be damped/dissipated when you’re clamping between 2 solid objects unless the shim is 2 layers with some of visco-elastic material between?
Ask to see the test results?
The only way it could help with vibrations is if it was a rubbish shim. I'm sure it's fine as a shim, but the vibration stuff smells like complete bullshit.
IANAMaterial scientist.
OP,I feel you have made a huge mistake.
If you had bought the wonder shims without questions,then the micro damping would have been amazing to ride with.
But you had to ask,and now you are doomed to never believe.
Do they do a Ti set 😆 🤣
Bad Omens! Beware!
I found some of those split shims in the bottom of a box and went to fit them on the unused stubby stem.
On removing the bolts to fit, what emerged was the skinniest, shortest bolts I'd ever seen on a stem. I weighed the new stem on my kitchen scales. 120g. And then the stem I was replacing, a retro Kore 25.4mm 42.5mm length hunk of chunk stem (224g). I'd save a whole 80g.
So, misgivings ahead, my torque wrench was set to 6nm from fitting the Kore stem. Maybe I should have knocked it down to 5mm.
Everything seemed to be going well until I tried to clamp down the last front plate bolt. Working diagonally, bit by bit,  that last one just didn't seem to tighten up. Then it got looser. I extracted the bolt and peeled the stem threads off it.
Doh!
The Kore stem went back on.
Personally, I wouldn't be shimming anything bar related, but it's your teeth, so who am I to say anything. Get a correct bar/stem for the job.
I've never had a bar slip when shimmed, and I'm not the smoothest rider.
The correct bar for someone on a low Stack bike and a 34" inseam is "whatever you can get where you live". I currently live in a land of little people where half the riders I see use a negative rise stem.
No idea, but it'd be interesting to try mastic tape as a shim and see if that made any difference.
Maybe they're comparing them to an unshimmed 31.8mm bar, we all know 31.8/35mm bars are a lot harsher than 25.4.
I used some 4-piece shims on my bars, and subjected them to some fairly rowdy riding on rigid bikes with zero issues, so I'd just get those. I probably got them of Aliexpress for a few pence though. No idea what they weighed, not enough to care about.
https://www.ebay.co.uk/itm/234913820376