Subject: Mounting Tubular Tires
From: Jobst Brandt
Date: January 26, 2001
Two kinds of glue are used to secure tubulars to rims, road and track, the latter having become uncommon. Over the years many glues have been available by: d'Alessandro, Clement, Continental, Michelin, Vittoria, Wolber, Pastali, Tubasti, and others. With the decline of tubular use, these brands have become so scarce that riders in the USA turned to other sources, one of which was 3M Fastack (R) that compares favorably with the others and cures faster than most.
Road tubulars preferably should have a rubberized base tape, one coated with latex, to improve adhesion to pressure- sensitive glues. These glues behave similarly to typical sticky tapes, sticking better to slick surfaces than cloth, so that rubberized base tapes stick better to partially dried rim cement than to bare cloth. Do not modify tubular base tape with cleaning solvents, because they affect rim cement adversely. Track tubulars, to be glued with hardening adhesive, should have bare cloth base tapes because shellac type track glues adhere poorly to rubberized tape. Hardening glue is used on track tires to avoid rolling losses typical of pressure-sensitive rim cements.
Because road tires are intended to be changed on the road, their glue must be manually separable and reusable; it must be sticky. However, being gooey, it allows the tire to squirm on the rim, which causes rolling losses independent of inflation pressure. That road tires move on the rim is apparent from the aluminum oxide (dark grey) that invades rim cement during use, and cloth-textured wear marks from base tape in the rim.
Stretch the new tubular tire on an old rim, inflate hard and let stand while applying cement to the rim on which the tire is to be mounted. Rim cements dry fairly rapidly, some faster than others. A low-viscosity rim glue may require more than one coat. Apply additional coats when the previous one has become firm enough to not draw strings when pressing the finger into it.
When a good coating (0.5 mm) of rim glue has set enough to be firm to the touch, deflate and remove the tire from the stretching rim and mount it on the glued rim. With the wheel standing upright on the floor, start by inserting the valve stem into the rim and stretch the tire, pulling down with the hands to both sides away from the stem, working around the rim until reaching the bottom with only a short section of tire not yet in place. Lift the wheel and thumb the remaining section onto the rim. Inflate the tire enough for it to take shape, centering it on the rim before inflating hard.
Were the glue still soft and mobile, it would get on the sidewalls while mounting the tire. Glue should be firm enough to not make a mess. Because pressure-sensitive glues are also thermally sensitive, heat from braking, while descending mountains, often melts rim glue enough to make it flow from under the tire -- in contrast to hard (track) glue. While track glue (Tipo Pista) is more cumbersome to use, it has its benefits for heat but primarily for timed events where fractions of a second make a difference.
Mounting track tires is done the same way as with road glue only that it takes several coats of shellac, the last of which must not be allowed to dry, so the bare cloth rim strip will be wet by the glue as the tire is inflated. Mounting the tire cleanly is more difficult and removing the tire sometimes requires tire irons.
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