Contradicting tubular glueing instructions: Campagnolo & Con

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TheDarkInstall
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by TheDarkInstall

Just get Miyata tape. Job done, and you don't need to go anywhere near glue.

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11.4
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by 11.4

First off, different rims and different tires can call for different gluing technique. And technique is really dependent on how bulletproof you want your glue job to be. Some people here leave an unglued area just to make it easy to peel the tire off, while others want the tire on so nothing will take it off.

Here are a few random thoughts:

1. Gluing so the tire is stuck on at 60 psi is all well and good but you can take an old rim and an old tire, both with old rim cement, and at 60 psi that tire will be stuck pretty well. But first time you flat on a descent or in a race and have to ride that flat tire through a few turns or simply at speed, you'll appreciate a more secure gluing job. Your glue should keep your tire on the rim with no air pressure in the tire.

2. Some tires have finer base tapes that get coated with rim cement in one coat, but others (like Conti) can soak it up and need more than one coat. There's nothing dogmatic here about number of coats. But if all the glue is soaked into the fabric tape so you can't feel a tacky layer on top of the cotton, it isn't where it needs to be to do its job. The second coat will usually do the job. I've had tires that needed three coats to have enough glue on the tire. Remember how this glue works. It's a contact adhesive, which means it works by electrostatic attraction. It sticks to itself, and it sticks to hard surfaces such as aluminum or carbon. It doesn't stick well to fabric, so on tires you need that textile weave to give a surface it can soak into to create a mechanical bond.

3. Everyone understands that you have to have a face to face contact between the tire and the rim for the glue job to work. That means the cross-sectional curvature of the rim profile has to match the cross-sectional curvature of the tire reasonably well. If not --- and it often doesn't match well -- the tire will either not be glued in the middle or won't be glued at the outer edges. In either case, as you ride you can rock the glue joint enough to make it separate. Now one of the important characteristics of rim cement is that it self-heals. By this I mean that if it pulls loose right at the contact patch, it will readhere without difficulty. There are many reasons why one doesn't want to have a bulletproof, never-breaks-loose glue job, so you want instead to have something that self-heals. But if it breaks free constantly it finally gets contaminated and doesn't restore itself, plus it finally pulls the glue off the rim or off the tire, at which point it may no longer work. One has to think about how the glue works when deciding how to do a glue job in the first place.

4. If you are gluing for straightforward training rides in sunny weather, you can get away with less of a glue job. If you puncture you aren't likely to be going flat out through a turn and your glue job isn't going to be compromised by water (when rim cement gets wet it no longer self-heals as efficiently, so you really want it to be stuck on well in wet conditions, even more so in dirty conditions such as cyclocross). And your tire doesn't need much to stay in place under less challenging conditions. However, if you are racing, or if you like to bomb twisting descents, or are otherwise putting more stress on your glue joint, you need a better gluing job.

5. Pro mechanics will sometimes be slack with their glue jobs because they have a lot of wheels to deal with and it's almost physically impossible to do a slow and careful glue job on 60-80 wheels while on the road at a stage race. Plus, pro riders are used to lots of miles and to more flats, so they know how to handle them better than most of us. But I've seen track wheels that peeled their tires off when riders simply bumped, and I've seen pro road riders lose tires as well. You can probably bet the Froome's or Nibali's mechanics do a careful job on the wheels for their lead riders. Those bikes get a lot of extra attention because of who the riders are, but domestique bikes and wheels won't necessarily get the same treatment. You and I do have the luxury of gluing a tire well, with the extra margin of safety that goes with it. So why not? If you don't want to, just stay behind me so you don't bring me down.

6. As far as tape, I really don't recommend most tape in lieu of glue. You can learn to apply and remove it efficiently, but it isn't always the most secure bond. The Effetto Mariposa tape is new to the market and people are having better experiences than with older tapes, but it's still a bit spotty -- I've seen it work really well and seen tape jobs that peeled loose far too easily. It doesn't help that a job may be just fine for one person who doesn't push his tires but isn't sufficient for someone else who either races hard or who simply wants a most secure glue job. I'm experimenting with it on training rides, but have had a few bad jobs for no clear reason. On the other hand, it may be more secure than a glue job done in a haphazard way.

This subject has been beaten to death countless times here, and there are a couple big sticky threads on the subject. So to the OP, I'd suggest you read those to understand more of why there is not as much agreement as you might expect on this subject. Different standards and expectations, different tires and rims, different gluing techniques, and different riding conditions and styles all affect how much you need to do. Starting out, I'd do the full job and only experiment with less as you have some experience. It's not just your skin, but that of anyone you ride with. I've been taken down by a couple rolled tires by people who thought they could do a Tufo tape job or an instant two coat glue job and immediately race. Some people don't care what they do or whether they make other people assume risks as well. Please don't be one of those.

graeme_f_k
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by graeme_f_k

11.4 wrote:First off, different rims and different tires can call for different gluing technique. And technique is really dependent on how bulletproof you want your glue job to be. Some people here leave an unglued area just to make it easy to peel the tire off, while others want the tire on so nothing will take it off.

Here are a few random thoughts:

1. Gluing so the tire is stuck on at 60 psi is all well and good but you can take an old rim and an old tire, both with old rim cement, and at 60 psi that tire will be stuck pretty well. But first time you flat on a descent or in a race and have to ride that flat tire through a few turns or simply at speed, you'll appreciate a more secure gluing job. Your glue should keep your tire on the rim with no air pressure in the tire.

2. Some tires have finer base tapes that get coated with rim cement in one coat, but others (like Conti) can soak it up and need more than one coat. There's nothing dogmatic here about number of coats. But if all the glue is soaked into the fabric tape so you can't feel a tacky layer on top of the cotton, it isn't where it needs to be to do its job. The second coat will usually do the job. I've had tires that needed three coats to have enough glue on the tire. Remember how this glue works. It's a contact adhesive, which means it works by electrostatic attraction. It sticks to itself, and it sticks to hard surfaces such as aluminum or carbon. It doesn't stick well to fabric, so on tires you need that textile weave to give a surface it can soak into to create a mechanical bond.

3. Everyone understands that you have to have a face to face contact between the tire and the rim for the glue job to work. That means the cross-sectional curvature of the rim profile has to match the cross-sectional curvature of the tire reasonably well. If not --- and it often doesn't match well -- the tire will either not be glued in the middle or won't be glued at the outer edges. In either case, as you ride you can rock the glue joint enough to make it separate. Now one of the important characteristics of rim cement is that it self-heals. By this I mean that if it pulls loose right at the contact patch, it will readhere without difficulty. There are many reasons why one doesn't want to have a bulletproof, never-breaks-loose glue job, so you want instead to have something that self-heals. But if it breaks free constantly it finally gets contaminated and doesn't restore itself, plus it finally pulls the glue off the rim or off the tire, at which point it may no longer work. One has to think about how the glue works when deciding how to do a glue job in the first place.

4. If you are gluing for straightforward training rides in sunny weather, you can get away with less of a glue job. If you puncture you aren't likely to be going flat out through a turn and your glue job isn't going to be compromised by water (when rim cement gets wet it no longer self-heals as efficiently, so you really want it to be stuck on well in wet conditions, even more so in dirty conditions such as cyclocross). And your tire doesn't need much to stay in place under less challenging conditions. However, if you are racing, or if you like to bomb twisting descents, or are otherwise putting more stress on your glue joint, you need a better gluing job.

5. Pro mechanics will sometimes be slack with their glue jobs because they have a lot of wheels to deal with and it's almost physically impossible to do a slow and careful glue job on 60-80 wheels while on the road at a stage race. Plus, pro riders are used to lots of miles and to more flats, so they know how to handle them better than most of us. But I've seen track wheels that peeled their tires off when riders simply bumped, and I've seen pro road riders lose tires as well. You can probably bet the Froome's or Nibali's mechanics do a careful job on the wheels for their lead riders. Those bikes get a lot of extra attention because of who the riders are, but domestique bikes and wheels won't necessarily get the same treatment. You and I do have the luxury of gluing a tire well, with the extra margin of safety that goes with it. So why not? If you don't want to, just stay behind me so you don't bring me down.

6. As far as tape, I really don't recommend most tape in lieu of glue. You can learn to apply and remove it efficiently, but it isn't always the most secure bond. The Effetto Mariposa tape is new to the market and people are having better experiences than with older tapes, but it's still a bit spotty -- I've seen it work really well and seen tape jobs that peeled loose far too easily. It doesn't help that a job may be just fine for one person who doesn't push his tires but isn't sufficient for someone else who either races hard or who simply wants a most secure glue job. I'm experimenting with it on training rides, but have had a few bad jobs for no clear reason. On the other hand, it may be more secure than a glue job done in a haphazard way.

This subject has been beaten to death countless times here, and there are a couple big sticky threads on the subject. So to the OP, I'd suggest you read those to understand more of why there is not as much agreement as you might expect on this subject. Different standards and expectations, different tires and rims, different gluing techniques, and different riding conditions and styles all affect how much you need to do. Starting out, I'd do the full job and only experiment with less as you have some experience. It's not just your skin, but that of anyone you ride with. I've been taken down by a couple rolled tires by people who thought they could do a Tufo tape job or an instant two coat glue job and immediately race. Some people don't care what they do or whether they make other people assume risks as well. Please don't be one of those.


+1!

Especially the last paragraph. Like most things, mechanical, if you are riding in company, you have a responsibility to others as well as yourself!

Remember too, if you are advising others - a bit of CYA is a good idea! It's expensive being on the harsh end of a liability suit ... plus if someone *really* gets hurt, or worse - you have to live with that for the rest of your life.

I've been gluing tubulars for everyone from myself to World Champions and Classic winners for 35 years. I have only ever had one tyre roll on a rider and that was because I was persuaded against my better judgement to take a chance and use tape a couple of hours before a stage start - it was a crit stage on a split-stage day, it was non-critical to the rider (but they wanted to use their own "best" wheels that they had flatted that morning, not a team spare wheel) - they insisted & the DS over-ruled me. He never did it again, as the rider ended up with a busted collar bone and bought two other riders down. Lesson learned.

And yes, I do take 12 hours between coats if I can. I use mastic, not tape, I key the rim and am fussy about cleanliness of the rim, cleaning with acetone or alchohol before applying a first coat. I'll usually apply two or three (or more) coats of thinned cement to the base tape - I pre-prep all of my tyres well before they are needed, so I can save time doing this on the road, storing the tyres on clean, unused rims to keep the prepared surface clean. The thinning will let the mastic properly penetrate the tape so that, as 11.4 says, I end up with a proper glue to glue bond, not a weak glue to fabic bond.

Multiple layers on the rim can help with slight mis-matches (which are virtually inevitable) between tyre curvature and rim curvature. The mastic layers are pretty thin but glue remains pliable even after drying and appears to "slow flow" from areas of high pressure (right under the stitching, say) to areas of low pressure (generally toawrds the edges of the tyre-rim junction), so giving a better bond. Tape cannot do this.

Bear in mind also that tape is contra-indicated by Campag on their carbon rims. It is a warranty no-no.
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Calnago
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by Calnago

+2
Last two posts by @11.4 and @Graeme_f_k really covers it.
Colnago C64 - The Naked Build; Colnago C60 - PR99; Trek Koppenberg - Where Emonda and Domane Meet;
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11.4
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Joined: Tue May 23, 2006 4:33 am

by 11.4

Just a perspective for a new tubular user? Consider this. As you are learning, you are subject to making mistakes. If you make a mistake in gluing it is likely in the direction of a bad glue joint, leading to a rolled tire. So when you start out, and until you are an accomplished tire gluer, go the extra steps and do it the conservative, anal-compulsive, obsessive way. It reduces your risk if or when you do screw up. When you nail every glue job, decide whether you can pull back a little. There are people on here who are expert with rim cement who can judge when they can skip a coat of rim cement, or when they can apply two glue coats close together. A lot of that comes from experience. Keep a band of safety between you and a rolled tire. Overdo the glue job on your tubulars for a while and next year or year after, start trimming your process a bit. After all, how many tires are you really going to glue in a year, and don't you want everyone to know you as a safe and mechanically adept rider?

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Calnago
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by Calnago

Funny, in my post praising yours, I was going to add "this covers everything except gaining actual experience to know when to adjust things a bit". And then bang, you covered that too 11.4. Thumbs up.
Colnago C64 - The Naked Build; Colnago C60 - PR99; Trek Koppenberg - Where Emonda and Domane Meet;
Unlinked Builds (searchable): Colnago C59 - 5 Years Later; Trek Emonda SL Campagnolo SR; Special Colnago EPQ

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