Bora tubulars - have you sanded them before glueing tubulars

Everything about building wheels, glueing tubs, etc.
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by hannawald

I can see in the manual that you should sand the rims with 120 grain sandpaper and clean with acetone before applying glue.

Did you do it? It just sounds weird to me to apply sand paper and 120 grain is a bit rough..i asked my lbs but they said they had never done such a thing and told me to watch videos how pro mechanics glue tubulars, that they don't really care at all, don't apppy 3 layers a bit confused:)

by Weenie

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by sungod

new cf rims may have traces of mould release compound on them

you use a fine abrasive to just scrub the surface clean (i prefer 0000 steel wool as it's easy to made a wad that matches the rim bed)

you only do this once in the life of the rim

then degrease with acetone and you are ready to glue

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by hannawald

Thanks. How do i recognize how much force/energy to apply? What is the desired state?:) Is there anything visible i should get rid of? I know you should probably not sand through carbon fiber. When sanding black dust, it is probably carbon fiber and you should not continue..? I havent found any tutorial on youtube..or is it just a quick few seconds job?

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by Calnago

It’s super easy. I use 180grit, because I didn’t have any 120. Cut a little piece about 4inches long and wide enough to curve around the rim bed. Then just give it a little rub once or twice around. You’re taking off hardly anything. You just want to dust up the surface a bit. Once when new, that’s it. Then use acetone on a rag to clean off the dust. Takes 2 minutes.
I’ve glued some up without even doing this step, but I like to give new rims this treatment now. Just seems a better surface for the glue.
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by RyanH

Glue doesn't adhere well to perfectly smooth surfaces, so the idea is that scuffing it up creates a surface that glue will better adhere to. I always do this step. Cleaning the rim/wiping down with acetone or alcohol is super important as well. I've skipped that step and when I went to pull the tire my rim was mostly clean (meaning, glue did not adhere all that great to the rim).

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by hannawald

Thanks, I got it. Just very lightly to make micro scratches..everything so confusing, i was hoping for some golden standard:) Somebody say sand, somebody not sand, somebody say acetone, somebody alcohol as acetone may harm carbon..but your recommendation follows Campy manual (sand+acetone) so i will follow it..

by Weenie

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by erik$

Ideally you will want to do cleaning with solvent, light sanding and then solvent cleaning again. This is fairly standard practice with composites at least, and should be just as relevant when bonding a tubular to a rim. I remember 3M writing about this 3 step process in their datasheets for some of their materials, and it is also mentioned by Mr Crumpton when he is bonding together pre-made parts.

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