"Carbon paste" on metal bars

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familyguy
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"Carbon paste" on metal bars

Postby familyguy » Wed Sep 20, 2017 8:57 pm

I've got a torsion issue with some Cinelli Giro bars and XA stem. Both are 26.0 clamp as best I can tell. Even at the matched size, it feels like the clamp bolt has bottomed out/reached max tension before removing the opportunist for it to twist. Hit a bump and they definitely move.

I've used CF paste on Deda 26.0 stem and shim combo with 25.4 bars, which was nice and solid once applied and tested.

Is it a bad idea to use on the Cinelli combo to stop them moving?

Jim

ironhanglider
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Re: "Carbon paste" on metal bars

Postby ironhanglider » Wed Sep 20, 2017 9:22 pm

I'm pretty sure that Cinelli made XA stems in 26.4mm as well...

Cheers,

Cameron
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Duck!
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Re: "Carbon paste" on metal bars

Postby Duck! » Wed Sep 20, 2017 10:13 pm

ironhanglider wrote:I'm pretty sure that Cinelli made XA stems in 26.4mm as well...

That would be irritatingly unique..... 25.4mm (1" for the imperially-minded) was quite common, but I have never heard of the decidedly oddball 26.4mm, because it has no immediately obvious imperial equivalent (but then neither does 26.0mm).
I had a thought, but it got run over as it crossed my mind.

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familyguy
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Re: "Carbon paste" on metal bars

Postby familyguy » Wed Sep 20, 2017 11:00 pm

Yep, I believe they did make 26.4 XA stems as well. This one is 26.0 best I can measure (with some great Mitutoyo verniers). Shims and CF paste fixed the last one, should fix this one.

Jim

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AUbicycles
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Re: "Carbon paste" on metal bars

Postby AUbicycles » Thu Sep 21, 2017 6:08 am

I don't think Carbon Fiber paste is the right way to go. The grit would either get crushed so slide anyway as the surface of resin coated and uncoated carbon fiber is different that aluminium.

The best idea I have is a shim but the concern is that if it is not grooved then it may still be prone to slipping. In theory, if you got some thin sheet aluminium and hand-notched on bother sides with a scribe then it should have enough ridges and troughs to ensure there is no slippage. I have no doubt that there are a lot of solutions that will give you the clamping pressure, but the concern is slipping unexpectedly.

The DIY solution is a coke can or beer can, cut a strip and then sand both sides to take back surface coating. Then notch it with a scribe (or your old school compass or a blade). If a strip around the entire circumference is too big, then just use half.

Cheers
Christopher

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familyguy
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Re: "Carbon paste" on metal bars

Postby familyguy » Thu Sep 21, 2017 8:40 am

Park have their SAC-2 (http://www.parktool.com/product/supergr ... ound-sac-2) for alloy parts such as this.

Some of the wedge expander XA stems were 26.0, but all the conical plug ones were 26.4 from what I can see. I took a conical plug stem off and put this one on, so it should matchy match, but you never know that one time... I will confirm the bar and stem clamp size this weekend.

Jim

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Re: "Carbon paste" on metal bars

Postby davehirst » Thu Sep 21, 2017 7:54 pm

I use a fine grit wet and dry to shim, never slips

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