DiabloScott

Yes, and post video here for future reference.

MooneyBloke

Gluing question for the peanut gallery: assume you have a decent glue base on the rim. How fresh does the glue on the tape need to be? I'm thinking that the solvent outgas from the fresh rim application will soften and fuse with old tape glue, and it might make sense to apply the tape glue and let it dry a day before putting a fresh tire on a clean rim to stretch. Also, that gets a tire ready for folding as a spare in case one doesn't have an old nasty sitting around for the purpose. Thoughts?


Addendum: the picture here is (at least) three glue applications: the dry glue base on the rim, the dry tape glue on the tire, and a fresh wet application to the rim just before mounting the tire. I'm not suggesting simply mounting dry glue to dry glue though that's what you're doing when you mount a spare on the road.

Many thanks to DiabloScott for teaching me the three-fold tire wad for spares.

DiabloScott

Like a lot of things, it's a matter of degree. I propose a sliding scale of 0-10 for estimating the security of a glue job.

Zero: no glue on rim, no glue on tire. You could ride this in an emergency if you're really careful with braking and turning... pump up pressure to max.
Ten: perfect preparation, perfect glue application, perfect curing time. You could ride this in a 6-corner criterium in August. You'll probably ruin the tire if you have to take it off.

Replacing a flat on the road with a pre-glued spare would be about a 3 - good enough to finish the ride if you're not worried about another flat.
I figure my process for a new install gives me about a 7 which is safe and confidence-inspiring; more than that is just pointless overkill for my riding.

I submit that if you had a 7, then needed to replace a tire and you put on a tire that had fresh glue 6-months ago and put it on the rim you just took a tire off of (clean, garage conditions)... that'd be about a 5.

MooneyBloke

That isn't quite the question proposed. What I'm interested in is if a fresh application of glue to a rim with a glue base preceding the mount of a tire with dry glue on the base tape activates the dry layers sufficiently for for the bond to be considered good. More to the point, must the glue on the base tape have been wet very recently for the bond to be road worthy?

DiabloScott

There is no "must".
Dry glue 5
Wet glue 6
On the DiabloScott tubular glue job security scale.

MooneyBloke

I tend to think there is a "must" if you want to take hard corners with a more than a small measure of confidence. I don't particularly like the taste of pavement.

Also, I'm not sure I'd call a glue job that destroys a tire on removal a ten. I'd consider a perfect glue job something I can remove by hand (thumbs to insert a round bladed tool and pull tool to lift off glue) but would never roll off in cornering.

The real question is how good a bond is tire:basetape:dry <--> wet:dry:rim?

I tend to think that the wet application will soften the dry glue and bond very strongly with it. I'd like an understanding to the contrary if I am wrong.

FWIW: if I'm in reasonable shape, I weigh about 142lbs hydrated, and I run 22mm (veloflex crits) front and back at 100psi/110psi respectively.

Classtime 

FWIW, I have mounted a spare on the road that had dry glue, and had a difficult time removing it after I repaired my good tire.

SJX426 

I wanted to try the Bianchi out prior to gluing. The valve moved enough to convince me not to do it.
NOS rims and new tires.

mosinglespeeder

agree 100%
only use a dry run to get home w/spare
wet rim glue, to wet tyre
the dry glue on the tyre will not reliably activate...and don't try the theory of natural selection to save a nickel...IMHO

MooneyBloke

I'm not trying to save a nickle. I'm trying to avoid redundancy. Sufficient as opposed to overkill.

I do think that tire glue is an area where there should be solid fact rather than religions and tribes. I want an engineering optimum. I.e. no more than necessary. No less than necessary.

I tend to believe that fresh glue in intimate contact with cured glue (at least of the Conti/Vitt Mastik One types) should give very good adhesion. Otherwise it seems that you'd have a lot of layer separation between subsequent glue layers. Here's the point: it you're doing brush application as I am, and mounting the tire soon after application, the wet glue will move into the irregularities in the tape and the existing glue base. There's really no place for the solvent to go but into the adjacent glue layers softening them. N.b. I'm not talking about a new tire which indeed needs an application to the base tape, nor am I talking about a bare rim surface. I'm trying to get to the truth about the solvent effects of wet glue on cured glue.

DiabloScott

The point is that there's a scale (I just made up) from 0 to 10 on how securely a tire is adhered to the rim, and 10 is the maximum possible. A 10 would hold the tire even on a folded wheel. A perfectly glued tire for most riding purposes is NOT a 10. More than 8 is probably too much, and less than 3 is not enough for anything besides limping home on a spare.

So I suggested that dry on dry is a 5 and wet on dry is a 6... you decide what your glue number is.
Then re-evaluate when you have to take it off.
If you used the wet tire glue-dry rim glue method (call it a 6) and you have to muscle off every inch of it when it's worn out... you can probably reduce to dry-dry=5. And if it comes off easier than you'd like, go up a number with another coat on the rim and some extra cure time.

It's possible that new wet glue will reactivate some of the old dried glue - it's a minor effect... the new glue just bonds better to whatever it touches.

Well no, but road worthy is also a scale. Dry on dry would be road worthy for a recreational century in less than extreme heat... maybe not so for descending French Cols in August at 80kph.

MooneyBloke

Ugh! How can I make myself clear? I'm trying to establish safe gluing practice with precisely NO waste. I do not think safety is relative here. Broken bones are not negotiable.

DiabloScott

Well I've answered your question three times now... I think you're not listening.

MooneyBloke

I think you're sounding a little careless to me. That's why I keep punching back. When it comes to gluing sew-up there's a lot of folk wisdom from elders, but damn little hard science and engineering. It drives me nucking futz. What I really want is a clear reason wet glue to dry is a less than ideal bond for the sorts of adhesives we are handling? It seems as if it should be, and I need an explainer.

DiabloScott

Stop thinking "ideal". Wet to dry is not as good of a bond as wet to wet simply because there's less active glue... but it might be good enough and only YOU can decide that. You could maybe get the same effect with using twice as much glue on only one surface but it would be messy.
The old dry glue is a benefit because the wet glue sticks to it better than to a bare smooth rim, not because the dry glue is doing any bonding.
You're right there's a lot of lore about this stuff, but nearly everyone agrees that you want the glue to be "boogery" when you pull up a deflated tire at the edge like this (doesn't apply to certain velodrome tires and glue).
More wet glue on the installation means more boogers. More boogers means stronger bond.


This is about a 6.

MooneyBloke

The problem I have with "not as good" is that the cyclohexane has nowhere to go but into softening the adjacent glue surface. I think if you wet a rim with a dry base coat with compatible adhesive (I really mean the SAME adhesive), and mount a tire with compatible glue on the tape, you'll still have plenty of boogers. The wet glue will fill the empty space in both dry surfaces, and the excess solvent in the wet glue will affect them rendering them sticky. I'm getting the feeling I need to play with a chunk of aluminum, some heavy duck cloth, and glue if I'm to get this thing resolved once and for all. I'm having a very hard time believing the wet glue application has inadequate effect on its neighbors.

DiabloScott

Buddy - just do your dry-wet method, let it cure for a couple days, and then evaluate. If you want more glue in there you can use the art syringe method.
There is no way you're going to get duplicable engineering accuracy on some coefficient of bondage without equally precise application techniques like temperature, glue volume, dry time, and other factors you won't have... and you don't need it. You need good enough - and then decide if you'd like a little more, and adjust your technique to suit.

79pmooney

MooneyBloke, do one approach. Ride it. Now pull the tire off. Your first data point. Too easy to pull off? Go up a step. Very hard? Go down a step. It won't take many cycles to find a level that work for you. Just skip the criterium corners until you get there.

Gluing tires is like fiberglass boat building back when it was done entirely by hand. You could write a book detailing how to do it perfectly but I would never go off shore on that reader's first boat. But I have trusted my life many times to fiberglass whizzes with the skill, touch and who were barely educated.

1989Pre 

Thanks for both the answers and the questions, folks. I am subscribed to this thread. I still have a lot to learn, and this makes it easy. A shout-out to Positron400.
Haven't taken the Grubb out,yet, still waiting for warmer weather, but I am a gentle rider and the roads are good. I think I'll have good results. Haven't bought my spare, yet, to bring with me, anyway.

mosinglespeeder

with all due respect, subjectively shooting numbers from the hip isn't really the index of measure we can rely on.

All I can say: I have looked at numerous ways to glue tubies over the year, and HAVE heard of the accidents, roll offs and problems of not just adhering to the tried and true practice of a TUBULAR specific glue, wet on wet surface.

Is it religion, no. Is it tradition, absolutely. Can it be natural selection, yes, I have seen it. Most are lucky enough to ride home and say 'don't do that again' and we chuckle. Many do it their way and that is fine, but when asking others for experience of others who have done this for years, it simply is what it is...that is just what I've/we have done and was taught. I humbly hope that helps and makes sense, and asking/thinking is EXACTLY what I did too, and came back to this method which is tried and true

DiabloScott

Even if we could have some objective measure of how well the tire/rim are bonded together, you would STILL have to determine what value is good enough for you... and it won't be the same as what's good enough for somebody else.
YOU have to decide if you want a shear strength of 1 Pa or 1 MPa or 1 GPa, and you'd have to use some kind of subjective reason for choosing your target value, and you STILL wouldn't be able to verify that your glue job corresponded to the test standard.

So in reality, you'd still be relying on somebody's (one day, your own) subjective experience riding sew ups to tell you how much is good enough for you, your equipment, and your riding conditions...whether you describe that in terms of shear strength, my 0-10 scale, or the number of visible boogers.

Is a wet-dry install better than a dry-dry install? That is a reasonable question.
What is the ideal bonding value and how does one achieve that value? That is not a realistic question.

Positron400

I am sure there can be some scientific values such as bonding force/removal force/bonding strength derived, if one was inclined to go that route. Even more so, i am 100 % confident the leading glue manufacturers (Conti, etc.) have had to do their own studies to have this product on the shelf and approved by the authorities, esp. if it is used by the pros. It's not like they would be sharing their results with us plebs, but still otherwise there would be WAAAAY too much liability.

squirtdad

it is really pretty simple. Tubular glue like Vittoria is like Contact Cement or rema tube patching cement which for proper adhesion need to dry first. if you have ever tried not waiting with either of those then you would understand The solvent that allows you to brush the cement on needs to "dry" to so as to not interfere with the bond.

the bond depends on both sides, so wet to dry will result in an inferior bond .....how inferior is an open question

mosinglespeeder

good point....and dry to dry in my experience has been just to get me home after a flat

EVlove

Quickly approaching... Most needlessly contentious topics



Case closed, as far as I'm concerned.