Technical FAQ: Gluing tubular tires for cyclocross
As promised, here’s the procedure for gluing a ’cross tubular tire so it won’t come off. Though it can still ruin your day, the downside of rolling a tubular in ’cross is generally not as big as in a criterium or on a winding mountain descent.
That said, the likelihood of a rolled tire is higher in ’cross, as you can see in three races in the early 2009 season when Jonathan Page was either the victim of a rolled tire or two or the winner who benefited from a competitor’s rolled tire (see “Compton, Powers rule USGP opener,” “Planet Bike 2: It’s Compton and Vervecken” and “Page doubles”).
Rarely do you hear of pro riders rolling tires on the road, despite many more events and competitors than in cyclocross, partly because high pressure in a road tire helps hold it on the rim. The low tire pressures used in ’cross (often around 25 psi compared to often around 125 psi for road racing) combined with: the bigger tire size providing more leverage against the ground to roll the tire, the fact that the bigger tires don’t fit down into rim channels designed for a smaller road tire, and the frequent mud soaking and washing that the wheels and tires receive, means that holding the tire on the rim is a more difficult proposition.
Also, a ’cross rider generally utilizes more wheels and tires for a given set of events, since different tread patterns and tire sizes can be advantageous, so travel to races with all of the equipment plays a role, as you can see in Jonathan Page’s blog on his three rolled tires in a weekend this past September shows (scroll down to the “Rolled tires update”).
Note also in Photo 1 how much flatter on the gluing surface the old Mavic GP4 is on the left than the 50mm-deep Ritchey carbon rim (center). That deep gluing surface is fairly representative of the rim bed shape on many carbon rims, as are the sharp edges as opposed to the GP4. The new Mavic Reflex rim on the right has more rim bed curvature and sharper edges than the GP4, but less than the carbon rim.
Gluing tubular cyclocross tires
While it is fine for the road, I don’t recommend glue alone for ’cross, and while it is fine for triathlons and time trials and may also be for road racing, I also don’t recommend using just tubular gluing tape and no glue. Using glue and “Belgian” tubular tape was suggested to me by Stu Thorne, owner of Cyclocrossworld.com and mechanic to Tim Johnson, Jeremy Powers, and Jamey Driscoll, and it really holds the tire on. But also pay particular attention to the second step if you have a Vittoria or similar tire, because all the rim cement in the world will not keep your tire on if the cement is not adhered to the tire.
- Before gluing a new tubular, stretch it first over a rim, inflate it, and leave it overnight or longer, making sure it holds air before you invest any more time in it (all tubulars with latex inner tubes bleed air and become softer, but not flat, overnight). To stretch it on, install the tire without any glue on it by using the method described in step 9.
- If it has a coating over the cotton, scrape the base tape of the tubular with the edge of either a serrated table knife or a half-round metal file to produce a good gluing surface (don’t chafe the sidewall with it). The woven cotton base tape on Vittorias and some other tubulars has a coating of latex over it to which the rim cement will not bond well. The tire can roll cleanly off of the rim, leaving no glue on the tire, if the base tape has not been properly prepared. Skip Step 3 for most Continental, Challenge, and Tufo tubulars, which usually have no latex over the base tape.
- Start by pumping the tire (not on the rim) until it turns inside out and the base tape faces outward. By using the serrations of a table knife or the rough side of a metal file, scrape the base tape back and forth until the latex coating on the tape balls up into little sticky hunks. Knock the bigger sticky globs off, but you can leave the smaller ones.
- Prepare the rim for glue. Sand it with sandpaper and remove the dust with alcohol (or acetone while wearing rubber gloves and a respirator). Roughing up the gluing surface with sandpaper does not help the tire stick to the rim better, but solvent will not remove everything (Teflon and mold-release compounds, for instance), and sandpaper can remove some invisible contaminants that would prevent the glue from sticking to the rim. I do the sanding, cleaning, gluing and taping on a truing stand, but if you don’t have one, don’t sweat it.
- With a rim that has been glued before, you can just apply a uniform layer of glue, unless there is a really thick, lumpy layer of old glue on the rim. In this case, scrape the big lumps off, and get the surface as uniform as you can, or strip the entire rim with acetone.
- Put a thin layer of glue on the rim, edge-to-edge (Photo 2), and a thin layer edge-to-edge on the base tape of the tire. After reading the gluing studies by Chip Howat, I recommend Vittoria Mastik ’One. I get it by the can and use a cheap acid brush to spread it on as in the photos. This is the most cost-effective way if you’re gluing more than four tires or so. I can probably glue 10 tires with a can. I wear rubber dish gloves to keep from getting my fingers sticky. If you’re using glue in a tube, I recommend having a couple of tubes per tire on hand. Squeeze a bead out of the tube and then put a plastic bag over your finger and spread the glue on the tire and rim thinly and uniformly. If you let the layer on the tire get too thick, the base tape of the tubular can become so rigid that it can tear. I now only recommend a single glue layer on the tire for this reason, unless you see that the glue has really soaked into the tape, in which case you should go ahead and put a second layer on as soon as you finish the first layer on the other tire. Let it dry overnight in a warm place (not in the cold garage).
- After the layer of glue on both the rim and tire has dried overnight, brush or smear another layer of glue on the rim. Let this set for maybe 15 minutes (or for how long it takes to glue the other rim), and put on a layer of the gluing tape, pulling it tight and centered onto the rim (Photo 3) and pushing it down into the rim bed with your thumb (with the top backing still on). Start at the valve hole and cut it off there as well.
- Peel the backing off of the gluing tape (Photo 4) and brush or smear another layer of glue on over it (Photo 5). Let this layer set for 15 minutes or while you brush the other rim.
- Deflate the tire, but leave enough air in it to give it a little shape. At this point, if you have a clean rim around, I can recommend local cyclocross and mountain bike legend Pete Webber’s “best gluing tip,” namely, once the glue on the base tape has set up, stretch it onto an unglued rim and leave it inflated until you’ve put the final layer on your rim. Deflate the tire – not completely! – and move it straight over from that wheel to the glued wheel. It does seem to make the final installation of the tire easier.
Mount the tire as follows:
(a) Stand the wheel up with the valve hole facing up.
(b) Put the valve stem through the hole, and, leaning over the wheel, grab the tire and stretch outward as you push the base tape into the top of the rim. Keep stretching down on the tire with both hands, using your body weight, as you push the tire down around the rim. I like to lean hard enough on the tire that my feet lift repeatedly off the ground. The farther you can stretch the tire at this point, the easier it will be to get the last bit of tire onto the rim.
(c) Lifting the rim up to horizontal with the valve side against your belly, roll the last bit of the tire onto the opposite side of the rim. If you can’t get the tire to pop over the rim, peel the tire back and start over, pushing down again from the valve stem. You want to avoid the temptation of prying a stubborn tire onto the rim with screwdrivers or other tools, as you will likely tear cords in the base tape and tire casing, leading to a bulge in the tire in this area.
By pulling the tire this way and that, get the edge of the base tape aligned with the rim. Your goal is to see about the same amount sticking out from the rim all the way around on both sides around the wheel.
Pump the tire to 60 psi and spin the wheel, looking for wobbles in the tire. If you find that the tread snakes back and forth as you spin the wheel, deflate the tire and push it over where required. Re-inflate and check again, repeating the process until the tire is as straight as you are able to get it. The final process will depend somewhat on how accurately the tubular was made; you’ll find that some brands and models glue on straighter than others.
Pump the tire up to 60 psi and leave it overnight to bond firmly. You can damage a cyclocross tubular by overinflating it.
You can get an even better bond by using a woodworker’s band (miter) clamp around the entire inflated tire. A miter clamp is a piece of nylon webbing with a cam-lock buckle on it. Depress the tab on the buckle to let out enough strap to surround the inflated tire and wheel. Pull the end of the strap to tighten the loop around the tire. Use a wrench to tighten the clamp and put extra pressure down on the tire to conform its bottom surface to the rim and bond it tightly.
Tomorrow you can drop the pressure and go ride or race on this wheel. I recommend putting sealant in it first.
Gluing carbon rims
As a deep-rim section is an advantage for steering in mud and sand, and aluminum deep rims are prohibitively heavy, carbon rims are extremely popular in ’cross. But Howat’s research indicates that tires tend to snap off of carbon rims, rather than peel off, meaning that it may take as much force to get them started off of the rim, but then they can roll right off, rather than requiring pulling and peeling to continue to get them off.
I think that the best thing you can do to preclude this is follow the above multiple-layer gluing and taping procedure with clean rims and scraped base tape. I theorize that the gluing tape, by having some structural integrity (the “Belgian tape” sold by cyclocrossworld.com consists of woven threads covered with sticky stuff) will tend to reduce the likelihood of the tire snapping off, since it will not peel easily off of the rim or the tire. I’ve found it to be a real bear to get a tire off the rim if it’s glued this way.
It’s still a good idea to re-glue at the beginning of the next season, however, as the glue can dry out and become brittle and less sticky, although the tape will still help with that.
Using Glue and Tufo tape instead
This fall, cyclocrossworld.com was out of stock for a long time on the Belgian tape, so I glued three sets of carbon wheels using the above method but substituting Tufo Extreme Tape. It seemed (and still seems) like they were really on there, but I rolled a front one at the Boulder Cup. The entire tire did not come off, just a 10-15cm section. I was amazed that it had happened at all and confirmed something about Tufo tape that I have received correspondence about in the past.
When I peeled the tire off (which was dishearteningly easy to do), I found the first, 20mm-wide, clear plastic layer pulled away fairly easily from the rim. It also was pulled away from the tire and torn where it had rolled. I could pull the rest of the entire clear strip off of the tire and rim all of the way around in a single piece, and when it came off, it was not at all sticky on either side.
While I have had many people write me about the great success they have had with Tufo tape alone not only holding their tires on in criteriums and other road events while being much easier to use than glue, I have had one letter from a furious reader who was injured when his Tufo tape delaminated and his tire rolled off, leaving a layer of tape on the rim and a layer of tape on the tire. Now I have had a similar experience, but with only mild scratches on my nose and knees to show for it.
Below that first transparent layer, there was yet another clear plastic layer, narrower than the first (13mm wide; see Photo 6), that had also peeled back a bit and was torn in that in one spot. With more effort, because it was fairly sticky on both sides, I was able to peel that layer off of the tire all of the way around in a single piece as well.
Still left on the tire was a narrow, white, gooey layer that is the white strip you see on a new roll of Tufo tape through the clear tape when you peel off the pink backing and apply it on the rim. That white layer I left on, because it was not only very gooey and sticky, but it also had no structural integrity and could not be peeled off in a strip; it would have had to be scraped off.
Now, however, I finally got more “Belgian tape” and glued my tires with it before this past weekend.
I cannot see the point of the multiple layers in the Tufo tape. It seems like a perfect tape would be essentially duct tape that had the same sticky surface on both sides and no shiny lamination on the top ─ just the woven fabric with sticky stuff on both sides, and that pretty much describes the “Belgian tape.”
Last year I used Tufo Extreme tubular tape to glue a pair of Continental tubulars to carbon Zipp wheels, I removed the tires for ’cross season and glued the ’cross tires to the carbon rims. It is time to glue the Continentals back on. My question is, if I now want to glue the tires back on to the rims (rather than using Tufo tape), do I need to remove all the tape from the base layer of the tires, or can I just glue over what is left of the tape? If I need to remove the tape what is the best way?
Remove all of the clear tape layers by peeling them off of the tire. If you can’t get the white gooey layer off, it’s probably fine to leave it on.
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