I was watching The Tour on the TV last week and the producers gave us a vignette on the art of gluing tires.
"First you apply a layer of glue to the rim and wait 24 hours. Then you apply a second layer the next day and wait 24 hours." The mechanic explained how he laid down glue on the rim for four consecutive days, and on the fourth or fifth day he glued the tire, and then mounted the tire.
A lot of triathletes are, like me, watching the Tour with keen interest, and I though this would be a good time to broach the subject of tires. One reason I consider it timely is that I think I need to fine-tune what the Postal mechanic said in a way that is specific to multisport.
This is because professional riders, and often even amateur weekend club road racers, do not change their flatted tires during the race. But triathletes do, with very few exceptions (there is a neutral support vehicle in the Hawaiian Ironman, and your flat tire may merit a wheel change, though it's often quicker to change the tire yourself rather than wait for the van to show up).
This means that you want to master the fine art of gluing the tire down so that it won't come off the rim while you're riding, but not so well that it's stuck to the rim so vigorously that you'll never been able to get the tire off on the road. I believe there is a safe middle ground, because it's not often that a triathlete gets himself in a race in which there's so much braking and turning that he threatens to melt the glue and roll the tire.
I might add as an aside that even for road racers the lecture this Postal mechanic gave seemed absurd. I've never heard of four base layers before the adhesive layer.
I called my roadie buddies, and they chuckled. I called Continental and Vittoria, and all of the old timers there were likewise bewildered. I'd suspect that if any mechanic tried to pull a tubular tire off a rim so-prepped, the tire would come off and the tire's base tape would remain attached to the rim.
As another aside, one might wonder why the Posties are even worrying about gluing tires down, since they ride Hutchinson a maker of clincher tires. Yes, Hutch's clinchers are quite nice I regularly ride them myself and have for years. But the Posties will race on tubs, as will pretty-much all the Tour racers, and the tubs the Posties use will almost certainly come from a small factory in Italy that only makes a finite amount of tires.
While the rest of the world's (production) tubs tend to come from Thailand (the biggest exception to this is the German tire maker Continental), the tire sponsors line up at this small hand-made factory to buy up their annual supply just for the teams they sponsor.
You'll notice that the two most scientific teams in the Tour Postal and ONCE both ride Hutchinson, and it is these "Hutchinsons" they're most likely riding fat chance getting your hands on these. But I digress.
When you buy or build up a wheel, yes, the first thing you'd do is apply a layer of glue to the rim. I don't recommend using 3M Fast Tack for this. While this is an aggressive glue, it seems to work best if it's applied to a rim that's already got a layer of slower drying glue on it. So I'd recommend prepping the rim using any of the glues that are made specifically for gluing tires. I generally use Continental's glue, and this is the only "clear" glue I like. Other than Conti's glue, I prefer the "red" glues.
I've read that most rims are shipped with a coating of anti-corrosive substances that resemble grease, and that this ought to be thoroughly removed with solvent and a clean rag before you can put down the first coat of glue. Personally, I've never "prepped" a new rim in this way, and I've not ever found that my glue had a difficult time sticking to an "unprepped" rim. Let your own degree of analness guide you.
I don't use a brush, or brush cap, or anything like that. I put the tube of glue up against the rim, and I lay a bead of glue onto the rim, applying the glue only in the area between the spoke holes.
All I lay is a bead down the center of the rim, about a quarter of an inch wide. I'll lay this bead down for a span of four or five spoke holes. Then I'll use my finger yes, my finger and apply a tiny bit of pressure right on this bead, and this pushes the glue out and around my finger, and this forces the glue out to the edges of the rim.
Careful that you don't get the glue over the edge of the rim, and on the sidewall, because then you'll have a bit of a time getting it off (you will need solvent for that).
I apply the glue on the rim sections at a time for two reasons. First, as I rotate the rim around slowly while I'm applying the glue, gravity will make the glue start to run if I haven't smoothed the glue out, and if this happens it'll run down into the spoke holes. I don't want the glue down there, and you don't either, if you ever intend to true your wheels.
Second, I'm occasionally going to lay down more glue than is needed for a particular space between the holes, and when I do I can't spread this glue with my finger on an area that doesn't yet have any glue on it. I keep the glue entirely clear of the area immediately next to the spoke holes. I don't try to get it around the edges of the holes.
I'll lay perhaps two layers on the rim with the layers applied at least 12 hours apart. But I won't apply any more than two layers. Even just one good layer, plus a layer right when you're mounting the tire, ought to be enough. Too much more than that and you'll never get the thing off if you flat in a race.
If you've also got the tire handy, I'd also lay a bead of glue on the tire at the same time you're pre-gluing the rim, and let that dry. I don't think you need more than one layer on the tire. May as well glue your spare tire(s) as well. You're going to need a layer of glue on them if you have to use them during the race; that is, you do not ever glue a tire during the race, but your spare tire will adhere passably well to the rim enough to get you home if you need to change it during the race.
An unglued spare will not work quite as well (keep in mind that if you've got to change a tub in a race, you'll want to corner gingerly on the unglued spare).
Finally, you lay down a final bead on the rim, spread it out, and mount the tire. Some people like to have the valve toward them the tire and rim braced up against their stomachs and work the tire on around each end of the rim, finally forcing the last of the tire on the side of the rim furthest from their bodies. That works fine.
To get the last section of tire onto the rim without making a mess, grab the remaining 4 or 5 inches and lift the tire away from and over the rim. This can be difficult if you forget to stretch it beforehand.
If it's an obstinately tight tire, however, I have a fallback strategy. I have to take my shoes off for this, because it requires the toes. In this case the valve is positioned on the side of the rim away from me, and I pull the tire on while bracing the wheel with my feet toes between the spokes. I use my back and arms like a rower would, and there's no tire I've ever failed to get on this way.
Of course it's problematic if you're trying to get a tire onto a disc using this technique, and while I've never owned a Campy Shamal, that might be tough on the feet. It is also potentially more messy doing it this way. But if it's a tough tire to mount, that's how I'll do it.
I know lots of people who apply a layer of cement on the tire right before stretching it onto the rim, but I find this messy unless you're an expert at it, and I also find it a bit of overkill. If you've got a layer or two of dried cement on both the rim and the tire, one layer of wet cement on the rim just prior to mounting ought to be sufficient. I've never rolled a tire in my life using this technique, though I've been in races where others have rolled tires, presumably doing it the "right way."
You can wait 10 or 15 minutes between the application of the glue and the mounting of the tires if you're using sew-up glue, and doing so might make the process a little less potentially messy. But if you're going to use Fast Tack for the wet mount, then you've got to get the tire on the rim directly after applying the Fast Tack.
Should you use Fast Tack? Many racers do. I don't, and it's only because regular sew-up glue works fine, and I don't see any reason why I ought to keep track of two different glues for this operation if I don't have to.
The one caveat is time. If you used traditional sew-up glue you should wait at least 12 hours before doing any serious cornering. If you need to race right away you can use Fast Tack and corner within an hour. When buying Fast Tack, be sure you get the real thing. 3-M sells other trim adhesives in boxes nearly identical to Fast Tack. These trim adhesives do not work for bicycle tires.
If you've got glue on the side of the tire or on the braking surface when you're done, you can remove it with solvent and a rag, or just wait until it's dry and do it then. The cleaning operation is a little less messy when everything's dry.
After you've got the tire on the rim, hold the wheel at its axle and spin the wheel, looking straight down at the center of the tire, and position the tire on the rim so that its centered.
If you find yourself in a position where you can pick up some sew-up rims cheap, it's a good idea to do so. I've got a batch of them that I bought for $5 each because they were virtually unsalable as riding rims. But they work great for pre-stretching tires, and I'll store my tires this way as well (you just need a rim for this, not a built wheel).
They'll roll rounder if they're stored on rims. I also like the fact that pre-stretching them this way is less traumatic to the tire than standing and pulling on it. If you let it sit overnight mounted on a rim, you'll be able to mount it up in a hurry if you flat during a race.
I'm serious about pre-stretching your tires. I recently bought some 24mm Continental GPs, and they are gorgeous tires on which I very happily race. But when they first showed up there was just absolutely no way I would've gotten these tires on the wheels un-pre-stretched (without taking my shoes off by the side of the road and going through the process described above).
Mounting a clincher tire is quicker and not as messy as mounting a sew-up, but it does present challenges. (When I say "quicker" I mean you don't have to go through a pre-gluing process; but changing a sew-up tire is quicker if you've got to do it during a race).
First you need rim strips. Real rim strips, not duct tape or other facsimile. The leader of the pack in this category is Velox. One thing, though. Velox, or any cloth tape, is thicker tape than that made by Continental, and I've found that when you use Velox tape with Conti tires it can be a rough go.
Thicker tape very slightly expands the circumference of the rim. This means the tire will fit more tightly when you're mounting it up. I've started using Continental's plastic rim tape, and as M. Scott Peck might've said, "it's made all the difference." Mounting 23mm Conti GP3000s on a 650c wheel with Velox tape requires a set of levers even to get the first bead over the rim. With Conti's tape, my grandma could mount the same tire on the same rim with no levers on either bead.
It's my understanding that when the tire is inflated, the bead is not in contact with the base tape with most rims, so I can't see that the tire is more likely to blow off the rim under pressure just because it mounted up easier. I just can't see any justification any more for using thicker cloth base tape with any brand of tire but I'm happy to hear from anyone who thinks I've got a blind spot on this.
When changing a tire, remove the outer tire bead from the rim. Leave the inner bead. When removing the outer bead, if after placing the first tire lever you are unable to fit another in because the tension in the bead is too great, then relax the first, slip the second in and use both together.
Some people like to inflate the tube just enough for it to hold its shape (too much inflation and it won't fit inside the tire). What these people say is, without any air inside the tube, you might pinch it and this is problem you're most likely to run into.
Pinching the tube is having a part of the tube squeezed between the tire and where the tire seats on the rim. When this happens, the tube will blow; it's just a matter of time.
That's fine advice. Yet, though I used to inflate the tube just a tiny bit before inserting it into the tire, now I don't. Instead, I find that the best way to make sure that this won't happen is to roll the tire onto the rim without using tire levers.
This might sound difficult, but believe it or not, there's almost no tire you can't roll on without levers if you're of average or better strength. Try it before you decide that you can't do it. Just take your time. You might surprise yourself. (This is especially the case if you use thin plastic rim tape as explained above).
It's best if you don't leave the area around the valve as the last part of the tire you mount. In fact, I always take care of the valve area first. Make sure the valve stem points straight toward the middle of the hub, and in fact this is the case whether sew-up or clincher.
The easiest place for the tube to become pinched is around the valve. Make sure it's not pinched by pushing the valve stem back through the hole a bit to "unpinch" it if it's pinched. Then inflate the tire and check to make sure the bead is seated all the way around.
If you get a flat and have to change the tire, the most time consuming element of the change might well be finding where the tube is leaking, and determining whether the cause of the leak is still embedded in the tire. But the problem must be found or there is a good chance your new tube will flat as well.
Pull out the tube finishing at the valve. Inspect the tube, find the puncture, and then find the corresponding part of the tire, to see if there's anything embedded in it.