Gluing cross tubulars
This guys sounds like he knows what he is talking about
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It’s important to get a good seal at the edge, more important than on a road application. I like to get the large jug of conti glue, you need a fair bit to get the job done. Do a couple coats on both the rim and the tire, make sure to get all the way out to the edges. Mount like normal. It’s imprtant to check them a lot when racing in the mud, they seem to come loose pretty easy, take it easy with the pressure washer at the glue joint.
I’d steer clear of the tufo tape plus glue method, it makes a godawful mess if you have to remove it .
I got this from Greg Reain’s blog last year (which is pretty interesting to read), it was really good advice–the blog is at:
http://crazyfast.blogspot.com/2005_10_01_c…st_archive.html
here’s what he wrote:
Sticky Fingers
So, as promised I guess that I will give you the low-down on how I glue my cyclocross tubulars.
I should probably first point out that there is a pretty big difference between road tubulars and ‘cross tubulars in terms of how they stay on the rim. A road tubular at 8 bar of pressure will stay on the rim almost by itself, sans-glue. The glue is essentially there to prevent any movement between the tire and rim from starting in the first place. You can try this if you have a new tire and new rim at home; just throw the tire on the rim, pump it up and try to push it off. Hard, yeah? Now release the pressure to 1.8 bar (about 25psi, a standard CX racing pressure) and the tire will slide right off. Scary. That is why standard tub-glueing knowledge does not necessarily apply for ‘cross use – the only thing holding the tire on the rim is the glue, there is no help from air pressure.
Next up is the issue of tubular tape. Great for road applications, especially the Tufo variety, horrible for ‘cross. Here’s why. As has been repeated ad-nauseum in other tubular installation instructions, the bond between tire and rim at the very edge is über-important if you want to keep your rubber on. This is even more critical in ‘cross because there is so much water flying around on the course and from the ubiquitous pressure-washers. If there is any gap in this area, water and dirt will penetrate into the bond and weaken it to the point where it may fail in cornering. Tubular tape is bad because it never completely fills the interface between tire and rim. It also causes the center section of the tire to sit a little higher than the edges, making it easier for a gap to form. This is true even of the so-called “Belgian Method”, where glue is applied to both tire and rim and tape used to complete the joint. Another bone of contention here- if you are using glue and tubular tape, why not just use glue?
My solution to this problem is Vittoria Mastik´one – and lots of it. Next best is Continental. If you can get your hands on a big can of the stuff, so much the better. If not, be prepared to use about 3 (maybe even 4) litle tubes per wheel, if you are starting with new fresh rims and tires. My team-mate Jiri told me he uses 1 can for 4 wheels. That’s a crapload of glue. Some people will say that’s too much, but Jiri has also never had a rolled tub in 14 years of high level racing. You decide.
You should probably start by cleaning your rims, just a really quick polish with some light sand paper and then acetone should do the trick. Now you need to apply a relatively thin layer of glue to the rim, making sure that you get it all the way out to the edges of the rim. I don’t really care how you spread it, just get it on there. Take your tires, put a little air in them to make them easier to handle and put a thin layer onto the base tape, making sure the entire surface of the tape is saturated (but not dripping) with glue. Now you wait. General rule of thumb is 8 hours of drying time between coats on the rim, but basically as long as it is dry to the touch and not too rubbery you can apply the next coat. Ideally you should do 3 thin-ish coats to the rim this way. For most people who aren’t sitting around all day waiting for glue to dry this means three days. Somewhere in these 3 days you need to pull out the tires (remember them?) and put another coat of glue on the base tape. This layer should be über-thick – as thick as you can make it and not have it running off the tape as you apply it. This is when a brush of some type is required. Let that dry overnight too. Finally, on the fourth day you can put the tire to the rim. Put a medium-thick layer of glue on the rim, give the tire a quick stretchy-stretchy and fire it on the rim, starting at the valve. For God’s sake make sure you put the tire on in the right direction first, otherwise you will make an atrocious mess peeling it off while the glue is wet (assuming you didn’t make an atrocious mess putting it on. Sorry, can’t help you there!). Make sure the tire is centered, put it up to 4 bar and leave overnight. Next day, deflate the tire and check the edge bonding by going around the entire circumference of the tire (on both sides), trying to peel it off the rim with your thumbs. If any gaps form, you need to poke some glue in there and inflate the tire again. Leave overnight again. Check the edges again. Now nothing short of a herculean effort should separate the tire from the rim – this a good thing. The glue generally requires 24 hours from the time the tire goes on the rim to reach full strength.
Like anything related to bicycle mechanics, there is a certain amount of feel involved with all this. With tires and/or rims that already have glue on them, less glue will need to be applied. The end result should be somewhere around 0.5mm of glue thickness (even up to 1mm is OK). Sounds like a lot, but it works. With Tufos you can get away with less because there is no seam on the underside.
That’s the extent of my knowledge. Argue all you want, but I have never rolled a tub since I started doing it this way.
Please don’t sue me
GReain
3 Responses to “Gluing cross tubulars”
If you use 3 tubes of glue on one wheel you’ll have a mess. Use the Mastik or Conti, 3 thin layers on the rim and 2 layers on the base tape. The belgian method works well because the tape covers the spoke holes and adds more surface area and seals out the water from weeping in from the spoke holes.
Please don’t sand your rims especially carbon. Acetone is a good idea.
I glued up four wheels and used about 2/3 or 3/4 of a full pot. I sorta kinda use the method espoused but have modified it per Josh Snead’s reco. I put 2 layers on a fresh base tape (1 on a previously glued tire) and three layers on the rims plus a final layer on the base tape (for a total of 2-3). I get the glue even but not super thin. I also find that gluing a pair at a time works well for timing.
Anyway, in an evening I’ll do this to a pair 1) first layer on rims, 2) first layer on tires, 3) second layer on rim, 4) second layer on tire, 5) third layer on rim. The time it takes to make a nice even coat on each of the four components is usually enough for the least recently coated to be dry (unless it’s really humid). So I just start the next application right away.
Wait overnight.
Slather on a nice thick coat on the base tape. Mount to rim and roll the whole thing along a broom stick to set the tire. Inflate to max psi and 24 hours later they are ready to go. Repeat for the next wheel. If you put enough glue on the base tape for the final application, a bit will gush out when you roll it on the broom and inflate the tire. That’s good. It means you have an excellent seal at the tire/rim interface.
I don’t like the Belgian method because if you have to remove the tire for any reason, it’s a beeyotch. I’ve tried it and had to remove tires because 1) I tweaked a rim but the tire was almost new and 2) I cut a tire but the wheel was just fine. In both instances, the work quite outweighed the benefits.
I am glad that you point out that the person should poke glue into the starved joints upon inspection. I think that this is where many people go wrong, they fail to follow up and make sure that there is no place for the tub to start to separate from the rim.
Generally, I check my tubs every couple of weeks and patch up weak spots by dabbing glue into weak areas. I haven’t rolled one yet, not even close.