2.23.2009

Tech Talk Tuesdays: Glue Your Tubies!!!!

So, you've decided to purchase expensive wheels with glued on tires to "feel pro" and "maybe be able to win a race or something or at least not suck as much" because "this isn't near as effective a performance enhancer as getting a personal coach and/or just riding more, yet it is more expensive." Now what do you do next?

Read all instructions twice before mounting tires. I've been riding, gluing, and repairing tubulars off and on for the last 10 years. This is my method for gluing.

Robbie's Tubular Gluing Guide:

Things you need:

2 tubular tires with any valve extenders or sealant installed.

2 tubes glue. One is usually not quite enough, so it's nice to have an extra tube just in case. Note that at maximum you will need 1.5 tubes of glue, so 3 tubes should do two wheelsets.

Toothbrush for easy glue application. Don't use your good one as this will be it's last brushing.

Rubber/latex/nitrile gloves to keep your hands clean.

Acetone for safe rim prep and cleanup.

A week before you plan on using them.


Step 1: Stretching

Mount your tire onto your rim and inflate to 125 psi. Leave it there for at least a day, preferably a week. This stretches the tire out and makes mounting it with glue way way way easier. Note to see if there are any lumps or bulges in the tire. You may have to slightly widen the valve hole (not recommended for carbon) to get the valve to sit properly. Make sure to carefully inspect the tire because the warranty period ends when the tire is glued.

Step 2: Rim prep

This is an optional but highly recommended step. Dab a bit of acetone on a clean rag and clean the gluing surface of the rim. This assures a clean surface for proper adhesion. If you're extra paranoid about using glued on tires, you can rough the surface with emery paper (1000+ grit sand paper) and then clean with acetone.

Step 3: Gluing

Put your gloves on and get your toothbrush ready. You'll be applying a total of 5 coats of glue. Coats of glue need to be very thin. You don't want the glue on the rim any thicker than .5 millimeter. Glue needs time to set up between coats. I recommend a minimum of 8 hours between coats of glue, and prefer to let them sit for 24 between
coats.

Tire: 2 coats. Deflate the tire and roll inside out and hang on the back of a chair or similar. Be sure to protect whatever is around you because the tubular glue is tough to clean off fabrics (and, well, just about anything else too). Use your toothbrush to apply a thin coat covering the entire base tape. Let tire dry in a safe clean place, being careful not to contaminate the glue. After glue has dried, apply second coat in the same manner and let dry.

Wheels: 3 coats. Mount the wheel in a truing stand or on your upside down bicycle. Use your toothbrush to apply a thin coat of glue to the rim all the way around, being careful not to get any glue on the sidewall. Wipe off any glue on the sidewall with a clean rag with a dab of acetone on it. After the first coat dries, apply a second coat in the same manner and let dry.

Step 4: Mounting. This is the hard part.

Apply the third coat of glue to the rim and let sit for 15-30 minutes to let the glue get good and tacky before mounting the tire.

Wet your hands with water. This will keep the glue from sticking to your hands while you mount the tire.

Start at the valve. Install the valve and vigorously stretch the tire onto the rim, slowly working your way around the wheel evenly. When you get to the last few inches of the tire, you'll suddenly appreciate your patience in letting the tire stretch for as long as you did. Use your thumbs to lift the last bit of tire onto the rim. If you didn't stretch the tire vigorously enough when you started mounting, this will be impossible, or nearly so. You may have to start over a few times before you get the tire all the way onto the rim. Clean any glue off the braking surface with acetone.

Step 5: Centering

Once you have the tire on the rim, inflate the tire with just enough air for it to hold its shape. Use your truing stand or your brakes to center the tire on the rim. You need to make sure that the tire is centered and not twisted. You can use the base tape as a reference point, but don't rely on it as it may not be strait. Also make sure that the tire doesn't have any lumps or bulges and sits in the tire track all the way around.

Step 6: Waiting

Inflate the tire to 125 psi. Let sit for at least 48 hours before riding. This is to allow the glue to fully bond. The pros let glue
sit for a week usually. Skipping or skimping on any of these steps can result in a weak tire/rim bond and when a tire rolls off a rim, it isn't pretty. Just youtube Joseba Beloki's crash on stage 9 of the 2003 Tour de France.

Notes on tubular tires:

Just 'cause the max psi is really high doesn't mean you should run the max pressure. On anything. Ever.
The extra supple casing on the tubulars will allow you to ride slightly higher pressure than you might with a clincher, but I would recommend only going up maybe 10 or so psi. You want your tires to roll over little tiny obstacles, not bounce over them. 125 psi should be the max pressure for a big guy riding tubulars. I'm a small guy and I usually run 100 psi. It's more comfortable and there is a lot of evidence that it has lower rolling resistance than higher pressure.

The glue melts at high temperature. Don't leave your fancy carbon wheels in the back of a car on a hot day without cover. Don't do this for your fancy frame either actually. Also, your fancy carbon wheels don't dissipate heat like the old alu ones, which means you'll have to get better at descending. Dragging your breaks all the way down a long descent can result in glue softening and bond failure. You don't want that.

I don't have personal experience with the tubular tire tape, which is a dual sided tape made specivically for tubular tire installation made by Tufo. It saves you the trouble and mess of gluing your tires. It also elimintates the wait; they say you actually need to ride them directly after installation (which is quick and easy) to let the glue to bond properly. The advantages are that it is very quick and easy and seems to work just fine. The disadvantages are that it is difficult to replace a tire out on the road (as to say, change a flat tire. You have to carry the spare tire around with you), and is difficult to replace a tire in the shop without completely cleaning up the rim and tire and starting fresh. Doesn't sound too bad for most of you who will only ever race on tubulars and wouldn't repair your old tires anyway, which may someday be the topic of another post.

If anyone has any questions or comments, feel free to respond to this post.

Rock on

~Rolo

1 comment:

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