Un-gluing Continental Carbon cement

[Alexandrumarian]

A while ago I mentioned I will use Continental carbon for my first tubular job and someone was very curious how it will hold. There aren't so many reports online about it, and they are usually mixed.

Today I flat the rear in the rain, squirted 30ml of Stans plus CO2 and got home just fine (measured 5bars) but after I reinflated with air the sealant popped exposing a rather big hole and a bit of cotton so I decided to tear it off and film doing it.

Not the best movie but I guess you can get the idea. The effort needed goes from low to moderate. Most of the glue stayed on the rim. From the rim the easiest peel was on the center, where because of the deep V groove it was thick and not so tightly pressed in by the tire. In a few places I can see separation in between the initial dry layers. Glue up was per instructions, one layer on each surface, left overnight, third layer on the tire.

Wheel was used for a bit over 2000Km, including several steep descents where it was cooked well.

Since I don't have previous tubular experience I can't say it is a good bond or not, but for the curiosity will clean the rim and try Mastik One.

https://youtu.be/rmdPdaz1lkY
https://youtu.be/lZgV_DIPbDw

[beanbiken]

Just watched your first video and it didn’t fill me with confidence. I ride tubs myself but I'd like to believe they are stuck more secure than that

[Alexandrumarian]

Second video shows a part that let go a bit harder. But yes, overall, I would have liked a bit more effort. I could put up with it on the side of the road without getting sore fingers.

On the other hand, if the pressure is high it would not move. I just pressed up to high-thumb-pain on the other wheel and it is not moving let alone opening. I will still finish the big can at some point, but maybe try 4 layers, 2 dry and 2 wet (so final wet layer on both rim and tire). The solvent flashes very quickly so centering it was a pain and eventually a failure as it would set too hard from the initial contact.

And then looking carefully at the entire rim, I can say most of the glue has stuck to the rim, except the parts with low pressure towards the center where the glue layers separated. Trying to clean the rim with a wood tool doesn't seem to work. Tried harder and softer, pointy or flat shape (I work with wood). It doesn't budge or where it is thick, it smears a bit around.

So I would guess a stronger bond would come from better adhesion to the tire. My prep was to wipe with alcohol, perhaps sanding is needed. Looking at the next tires (Vittoria G+) I see a milky coat over the base tape which is probably the latex wash I've been reading about and some people remove. I can't recall if the Veloflex had this.

[UpFromOne]

Lifelong wheelbuilder here. You can prep Vittoria tubs by just sweeping on a thin glue layer over that base tape, and let it dry for a day. Then they're ready for the rim. but how you do the rim is the key. And I won't belabor all that info here, as the methods vary wildly. Suffiice to say that tire removal should be really difficult bare-handed. Your tire was NOT properly glued. And you'd be unpleasantly surprised at how a tubular can roll off the rim whilst cornering.

The biggest problem has always been how to clean up a rim, once there's enough glue build-up over a few tire changes.
After all these years the best I came up with is the Effetto Mariposa "caragna" glue remover, but it's a very slow and very messy process.
So if anyone has a great glue removal method, please post.

[Alexandrumarian]

After trying and failing in a few ways, I (partly by accident) came to this method: apply a generous amount of fresh glue on the rim, let it flash well (so maybe 15 mins but this will vary depending on thickness and type of glue) At this point the two layers will be bonded, the old layer softened, and the top not runny anymore. Apply pressure with your finger (or better with an eraser or any other hard rubber object) and the whole thing will start to peel and roll away. Maybe it will not work on alu but on my carbon it worked perfectly leaving a flawless surface with zero glue leftover. Wasn't super fast but far from super tedious, well under 1h.

[racingcondor]

I've used Conti for a few years and been pretty happy with it (Alu rim version though, not had much experience with the Carbon version).

Last time I cleaned a rim off I used Schwalbe glue remover, goes on a blue liquid then seems to form crystals as it eats the glue. Worked quite well but I do remember it being pretty unpleasant.