Conti Carbon rim cement - anyone ignored the instructions?

Everything about building wheels, glueing tubs, etc.
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chris101
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Joined: Thu May 12, 2016 10:34 pm

by chris101

Hi,

I've searched this forum for a while and not found a clear answer to this question, so apologies to all those that are sick of reading about rim cement. Not asking for advice on which is better, just on the process with this particular product.

The supplied instructions for the carbon rim cement say to apply one layer to the basetape, one to the rim, leave for 12 hours, then one final coat on the basetape and fit the tub.

As many have pointed out, putting the glue on the tub as the final step is going to lead to a really messy job, especially when wresting with a pre-stretched Conti Competition, so its natural to think that it'd be a cleaner job to instead apply this last layer to the rim, however the instructions at point 14 specifically mention not to apply the last layer to the rim. This is contrary to many other products, although this is a different product so there is probably a good reason for this logic.

Anyway, has anyone on here successfully used this cement and not put the final 'wet' layer on the tape?

I've always used Tufo tape in the past which was a good fit in the valley on previous wheels, but having now invested in much wider Zipp 303's I want to make sure I have got full coverage across the width, hence the move to glue.

Cheers!

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jimaizumi
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by jimaizumi

Yeah, I was darning myself to death too when I bought three cans of the new carbon cement and was watching the video on how to layer and mount the tires on to the rim.

Firstly, I have not tried to apply the third layer onto the rim as opposed to the following reasons
1) The glue itself is much thicker in texture and yes, it begins to dry and harden super fast. Because of this, I haven't really experienced any major issues when I mounted the "wet" tire onto the rim.
2) I noticed that due to the texture of the glue, it tends to have a hard time adhering to smoother surfaces, which makes the process of removing unwanted glue from the brake track that much more easier.

Now, IMHO, the real problem lies NOT in the installation process... because of reason #2, I've experienced multiple cases where the glue peeled off of the rim bed. Up to now, I have never experienced any issues of this sort with other glue incl vittoria/panaracer. I usually do not sand my rim bed as its never been an issue but I might need to with the Conti glue. The glue also has stronger adhesive properties to that of the tire vs the rim.

In the process of regluing the tire, the tire will usually pick up almost all of the glue off the rim bed. I'm not sure if this supposed to happen but in my logic, unlike mastik glue, the residual layer is left in in small spots tht can be easily peeled off by hand. My assumption is that the glue may have been designed in this fashion as a new layer would appear more functional vs having to layer "over" the old one.

Having seen the characteristics of this glue, it does somewhat make sense for the final layer of glue to be on the tire vs the rim. If the glue dries much quicker and better to the tire, then it will initially not hold a strong bond to that of layer on the rim. This will help ensure that the glue (on the rim) will not come undone when centering your tire on the rim.

Note, I am using this glue with a set of LW's which are known to have a very glossy rim bed whilst its likely that one may not experience the same issues I did with other brands that may come pre-sanded.
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Calnago
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by Calnago

Probably the two best posts I've read about using Conti Carbon Cement are right here. So good question and good response. I was going to try it when I got Carbon tubulars and that glue came out, but after talking to a number of folks who had used both it and Mastik One, it was pretty unanimous that Mastik One was the better choice. I also heard that the Conti Carbon Rim Cement was really nasty smelling. Would you guys agree with that?
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jimaizumi
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by jimaizumi

I'm no connoisseur of glue scent...If anything the Panaracer glue was the strongest of them all. For me it all smells....well, like glue...

Conti is a bit hard to get used to if one is switching from mastik. Its a bit gloppy, can get messy but can hold a strong bond. If you guage out the ease in pains within the entire process of having to glue and mount all the way up to removal and cleaning, mastik starts off easy and ends off in curses whilst Conti is the reverse... hah!
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beanbiken
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by beanbiken

jimaizumi wrote:
Conti is a bit hard to get used to if one is switching from mastik. Its a bit gloppy, can get messy but can hold a strong bond. If you guage out the ease in pains within the entire process of having to glue and mount all the way up to removal and cleaning, mastik starts off easy and ends off in curses whilst Conti is the reverse... hah!


And Magic Mastik promises it all........... hopefully it will deliver in time.
Ahhh, coffee & carbon

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jimaizumi
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by jimaizumi

Ah, if pics speak a thousand words, the image below should say everything.

This is what the glue looks like after being removed from both the rim and tire. This took all but 30m to complete.

Image
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Calnago
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by Calnago

Hmmm... that really does look like it just sort of "peels" off. Is that the Conti Carbon Glue I presume? I generally strip everything off a rim when I change tires and essentially start with a clean as new rim every time with Mastik One. Just don't like the idea of putting new glue over old and letting everything build up. Schwalbes Tubular Glue Remover actually makes the process of stripping pretty easy. I think I'll stick with Mastik One. Magic Mastik sounded promising but actual use stories seem to vary from ok to a nightmare of inconsistency. My understanding of the idea behind the special Continental "Carbon" Tubular Glue was that it handles heat better than the regular stuff. I've only used Conti regular tubular glue and Vittoria Mastik One and much preferred Mastik One, so I just stuck with it.
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sungod
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by sungod

Calnago wrote:...much preferred Mastik One, so I just stuck with it.


:)

as well heat resistance, i'm sure i read that the conti carbon glue was designed with lower adherence to reduce the chance of accidentally peeling off bits of the rim bed when removing a tub glued with stronger stuff

but, i too, have stuck with mastik one

chris101
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Joined: Thu May 12, 2016 10:34 pm

by chris101

Many thanks for the replies, much appreciated & mind made up! I wont even bother with the Conti cement, Jimaizumi's report of problems getting this stuff to adequately adhere to the rim seem widely reported, so will use Mastik 1 as 99% of what I'm reading about that stuff is positive.

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Rick
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by Rick

In the days when I rode tubulars, I was a big fan of the Conti cement, simply because I saw numerous other types on rolled-off tires during criteriums. But, of course that is just anecdotal; maybe they didn't do a good glue job.
But I always had the opposite problem with Conti: you have a REALLY hard time pulling the tire off even when you want to.
I always followed the Instructions, and i assumed that the extra layer on the base tape side was simply because the base tape tends to absorb the first layer a little into the fabric.
It was the yellowish-translucent glue on aluminum, not "carbon glue". So i don't know how that compares.

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Calnago
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by Calnago

@Sungod's post seems to make the most sense of the difference between the regular Conti glue and the Carbon stuff. I knew about the supposed higher heat tolerance but the less adherence part to prevent pulling away the carbon fibers make sense too. But I never just "yank" a tubular off a carbon rim for that very reason. In fact, it takes me a good 15 minutes to get a properly glued tubular off a carbon rim. These guys who say they can swap a tubular on the road within five minutes are definitley doing the full throttle yank and peel method. Ok for aluminum but I have seen fibers being pulled away, so if rather take my time and get a round tool (screwdriver handle) between tire and rim and work my way around to get it off without him any damage to the rim bed. I still like Mastik One over Conti glue. But if I'm using a Conti tubular I put two rounds of glue on the cotton tape since it soaks it up so much.
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11.4
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Joined: Tue May 23, 2006 4:33 am

by 11.4

The carbon version apparently has the same solids content as the classic version, but the solvent base is altered. The intended purpose, according to Conti, was two-fold: To reduce splintering of carbon rim tire beds and to deal with the failure of glue jobs caused by the coarse and very absorptive base tape on Conti tubulars. Their solution was to make the cement thicker, put the second layer on the tire so it helped fill the base tape properly, and to make it harden faster so it wouldn't soak into the base tape as much and wouldn't bond as tightly to a carbon rim. All in all, rather a botched job. We ran into the same kind of issues as described in this thread, plus others. The adhesive tends to pile up on the base tape rather than soaking in and adhering properly, so it actually peels off the base tape as well, especially when the base tape has been calendared. The bonding strength to the carbon layer is significantly lower; we found it simply peeled off in most cases, regardless of what we did for rim prep. In short, neither side works right. It's not our glue of choice.

DWatkinsBSB
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Location: London

by DWatkinsBSB

So what is your glue of choice?!

Thanks!

11.4 wrote:
Fri May 13, 2016 6:55 pm
The carbon version apparently has the same solids content as the classic version, but the solvent base is altered. The intended purpose, according to Conti, was two-fold: To reduce splintering of carbon rim tire beds and to deal with the failure of glue jobs caused by the coarse and very absorptive base tape on Conti tubulars. Their solution was to make the cement thicker, put the second layer on the tire so it helped fill the base tape properly, and to make it harden faster so it wouldn't soak into the base tape as much and wouldn't bond as tightly to a carbon rim. All in all, rather a botched job. We ran into the same kind of issues as described in this thread, plus others. The adhesive tends to pile up on the base tape rather than soaking in and adhering properly, so it actually peels off the base tape as well, especially when the base tape has been calendared. The bonding strength to the carbon layer is significantly lower; we found it simply peeled off in most cases, regardless of what we did for rim prep. In short, neither side works right. It's not our glue of choice.

chris101
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Joined: Thu May 12, 2016 10:34 pm

by chris101

Dunno about 11.4 but I used Mastik 1 and its been fine.

11.4
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Joined: Tue May 23, 2006 4:33 am

by 11.4

I still favor Mastik One.

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