Help! Question re: Mounting Reflex rims and Griffo 'cross tires

[jchasse]

I’ve got some reflex rims (new) with Griffo Challenge ‘cross tubular on them and I’m having some issues. First I decided to mount them myself with Mastik One. Several thin coats (I think it was 4) on the rims and tires, each allowed to dry completely before next was applied.

The tires were stretched prior to any gluing, but I don’t have any old tubular rims around so I couldn’t stretch them again after the glue was applied. Net result is that I really struggled to get them on the rims, so I decided to let the pros do it.

I took them to an LBS with a very experienced staff and had them mounted. I then did a very short (10-15 mile) and gentle ride on them, mostly on pavement…here’s where my questions come in:

1. First, these things are way out of round. It’s pretty noticeable at 45 psi on smooth surfaces. Is this normal?
2. After the ride I took one wheel off and was looking at it. With the tire mostly deflated, I squeezed the sidewalls together with two fingers (and I’m no gorilla), and the tire/rim bond gave up. I tried in several other spots on the rim with the same results, and it looks like there was virtually no bond down in the bed of the rim…just out at the rim edges. It seems like the channel on Reflexes are pretty deep, so I’m guessing the base tape never made good contact? Questions here are (1) how hard should it be to peel ‘cross tubies off, considering that I’d be running them with fairly low pressures? And (2) are Reflexes unusually “deep”?
3. *** should I do now?? Should I pull them both off and re-mount? What do I need to do to the poorly mounted rim and tire to prepare for re-mounting?
4. Would TUFO tape be a good fix here to help fill in the deep channel in these rims and ensure good contact? And is the tape compatible with the now existing glue that’s on there?

[mschol17]

Search for the belgian gluing method, which uses both glue and tape.

[sailorboy]

I've heard others talk about challenge cross tubies that aren't perfectly round, but I think when you are maxed out on a cross course or other off-road, you won't notice it.

I used some grifos passed down from e-richie last season, on a set of mavic helium rims, which I would suspect have a pretty similar rim depth to reflexes and I had no problems. These were applied using mastik one. Yes, when they are deflated you can tend to peel them off easily, but at full pressure (anywhere from 32 to 42 last season) they were solid under some fairly demanding situations. I would try riding them again moderately hard on trails and then see how you feel.

S

[caleb]

Do not have just any shop mount cyclocross tubulars. If they use a standard road gluing method they'll almost certainly roll off.

Pull the tires off and glue them yourself, or take them to a shop that you know deals with cross bikes a lot. Expect to pay through the teeth for them to do it right. If someone wanted me to glue their cross tires like I glue my personal ones, I'd have to charge $40-60/tire. It takes a long time and a pile of glue.

[djg]

It's hard to say whether it's the tires or the mounting, but I would pull the tire and try again before giving up on the tire. I've never put four coats of glue on a base tape, but I assume that you checked out the tape and the rim bed and that there weren't any lumps of glue anywhere. BTW, I think it really pays to have some old rims or wheels around for pre-stretching tires. It really shouldn't be hard to pick up some used ones relatively cheap (think, beat up old 7 or 8 speed wheels at the local swap, or on the bay or something). I know that some folks do a short roll-out to seat the tire after it's mounted, but I'd give it just a bunch of pressure (within rating, but way, way high for actual cross riding) and overnight before I went out for a 15 mile ride. Also . . . well, I glue my own tires. It's one thing to have a particular, trusted wrench do it for you, but just leaving it at the shop might mean that somebody with relatively little experience with tubular tires gets to practice on you and your gear (and your race, and your backside). It shouldn't be murder to get a properly glued tire off, but it really shouldn't just start popping off the rim with a little thumb and forefinger pinch, as you describe -- that doesn't sound like a proper bond to me.

[jroden]

You have to use a pretty thick and gooey coat of glue to seal those things and the glue has to be right out to the edges. You have to apply a nice coat to the tire and glop up the wheel, let it dry then do a thin coat to activate the glue and go to town. They are different from road tires in that you need a very good seal and a very good bond, otherwise they roll off when water gets between the bond.

I'm not a fan of the tape plus glue, it might make your situation worse and it's a bear to clean off the rim later.

When you are mounting the tire, start at the top and work your way down, then when your hands are at 9 and 3 o clock, push down very hard to stretch the tire, I suspectthat's what you were not doing, it makes all the difference

[jchasse]

Thanks guys, there's some good info here.

It'll be a while before i have time to tackle them, but i'm inclined to find an old wheel so i can properly stretch the tires and take another swing at doing it myself.

[11.4]

On Reflexes you are likely to have a little more difficulty of the kind you describe. Reflexes are made from a piece of aluminum tubing that is extruded with folds on each side of the tire bed and a fairly deep center section. For smaller (typical road) tires these work acceptably, but for cross tires you run into the problem you described. Not my favorite rim, but here are a few other things that may have gone wrong:

1. When you paint glue onto the rim and onto the tire, you have to get each coat right out to the edge of the rim or the base tape. The tendency is to miss those edges. Glue along the edges is critical to holding the tire in place. If it starts to pull loose at the edge, and you're on an off-camber slope or otherwise applying a lot of lateral stress, you'll strip the tire off.

2. Your last coat of glue, applied just before mounting the tire, has to be a bit heavier than with road tires. This is because the glue will tend to get pushed into the center of the rim rather than staying where it's supposed to.

3. You put a good base on the rim, but what about the tire? Those base tapes can sometimes require 3 coats because the base tape keeps absorbing glue. When it's done properly, you should see the whole fabric of the tape impregnated with the rim cement and the cement built up to give a more or less smooth surface. If you still see the fabric texture of the base tape, you didn't apply enough coats. Cross tires often require a lot of extra base tape coating to do the job.

A cross glue job should, if anything, be stronger than what you do on a road tire. There's a lot of leverage trying to strip that tire off, plus you don't have tire pressure to hold it on as well, plus the larger tire diameter means it doesn't seat itself into the depth of the rim tire bed. And both water and dirt rapidly compromise the quality of a glue joint, so your glue job certainly won't get stronger after a couple cross events.

Some people like the Belgian glue plus tape method, but the tape really doesn't do much more than provide an intermediate bonding base in the center of the tire bed. I can't say that it is better left off, but a good glue job will create enough base in the center of the tire bed to hold your tire on well. The engineering idea behind the tape is that the depth of glue unsupported by an intermediate structural support is less. However, rim cement handles such an unsupported gap just fine if well done. I'm not saying not to use tape, just that you can get an equal glue job without it. It's all a matter of process quality control.

Edit: And definitely re-stretch the tire after applying glue to the base tape. When it's extremely tight to fit, you'll have a poorer glue joint because some parts will want to flex more in use than others. Always try to have consistent tension around the circumference of the tire.