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Technical FAQ: Patching tubulars. Is it worth it?

  • By Lennard Zinn
  • Published Mar. 9, 2010
  • Updated Feb. 23, 2011 at 12:44 PM EDT

Dear Lennard,
How hard is it to patch a tubular? I have a couple that I punctured when they were brand new, and it seems such a shame, not to mention a lot of money out the window, to throw them away, but all of my buddies laugh when I say I want to patch them.
Jonathan

Dear Jonathan,
If those are slow leaks, put Stan’s, Caffélatex, or another liquid latex sealant inside (remove the valve core to do it), and call it good. If they can’t be sealed that way, think about what you intend to do with the tire before proceeding.

In the early 1980s, I spent countless hours patching tubular tires, often while sitting in the car on the way to distant races. But we were creating training tires, since there were no decent clincher tires and rims available then. Now that everyone trains on clinchers, patching tubulars is rare.

Tubulars may arguably still be the best tires for racing, being lighter, requiring lighter rims, and being able to hold tremendous pressures because of being sewn together (the high air pressure reduces the rolling resistance of the tire on the road). However, even though tubulars are expensive, it makes no sense to patch a racing tire, because you invest too much time, energy, and money competing in races to run the risk of getting a puncture because of a weakened tire.

If for some reason you still wish to patch a tubular, here are the steps involved:

  1. Remove the tire from the rim.
  2. Pump up the tire to 70 psi (50psi max for a cyclocross tubular), and find the leak by submerging the inflated tire in a bucket of water, continuing to pump as need be if it loses air too fast. If you’re lucky, air will come out through a hole in the tread. In the case of a pinched tube, though, the air may seep out through the casing randomly at the stitches, and be hard to localize. See the next step for help.
  3. In the region 2 inches on either side of the puncture, peel away the base tape covering the stitching. If you were unable to precisely locate the hole, try submerging the inflated tire now to watch the bubbles coming out through the stitching. Peel more base tape back if necessary until you are sure that you have exposed the stitching at the hole.
  4. Deflate the tire and carefully cut the outer layer of stitching threads for an inch or so on either side of the hole. Pull the casing open in that spot, and pull enough of the tube out through the hole to find and access the hole(s) in it.
  5. Patch the tube as you would a lightweight clincher tube. Use the same type of recommended patches.
  6. Push the tube back in place, and sew the opening in the stitching closed by hand. I recommend using a needle for leather with a triangular cross-section tip and braided high-test fishing line. Stitch one way across the opening, turn the tire around, and double back over the stitches again. For obvious reasons, be careful not to poke the tube. You may need a thimble to push the needle in and a pair of pliers to pull it out on each stitch.
  7. Inflate the tire to 70 psi or so (50psi max for a ’cross tire) to make sure all of the leaks have been patched.
  8. Deflate the tire and coat the peeled-back section of base tape and the exposed stitching area with contact cement. Barge Cement (originally made for shoes) works well. Wait 15 minutes or so for the glue to set, and carefully stick the base tape back down over the stitching. (If the tape stretched when you pulled it loose, it’s permissible to cut it and overlap the ends.)

Lennard

Dear Lennard,
When I read about your patching the same Wolber cyclocross tubulars so many times that you came back to your own stitching under the base tape, I was reminded of the way I kept myself in training tubulars years ago.

Back in the day, I kept myself in tubular tires by repairing them “one-for-two.” In other words, you give me two flat tubulars; I fix them both and return one repaired tire to you.

That approach kept me in tubular tires for a good part of my amateur racing career and made me intimately familiar with tubular tire construction. I got to the point where I could repair just about anything short of a shotgun wound. One of the cool things I learned was a way to splice latex inner tubes. This was especially helpful for tubular tires, particularly when you were searching for a small leak in an otherwise virgin top-dollar tubular tire and, searching, searching, pull, SNAP! Damn-it! The latex tube breaks in two.

Splicing a latex tube. | By Tom Petrie

Then only way to fix the tubular is to cut all seven feet of stitching, replace the tube, and re-sew seven feet of tubular…or splice the tube. I’ve done both; splicing the tube is easier.

I don’t know if this is of any use to you or not, or maybe it’s common knowledge. However, I’ve attached a sketch showing the steps. After splicing, apply talcum powder  liberally to any tacky parts in the splice area, and generally all over the surface of the tube before installing it in the tire. Talcing the tube helps to reduce the possibility of the tube vulcanizing itself to the tire under braking heat, it makes the tube better able to resist penetrations (because it can pull away from the interior surface more easily), and, I believe intuitively, reduces rolling resistance because the tube can slip against the interior surface.

Tom Petrie
Velimpex Marketing, Inc.

Readers can send brief technical questions directly to Zinn.

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Technical writer Lennard Zinn is a frame builder (www.zinncycles.com), a former U.S. national team rider and author of numerous books on bikes and bike maintenance including the pair of successful maintenance guides “Zinn and the Art of Mountain Bike Maintenance” – now available also on DVD, and “Zinn and the Art of Road Bike Maintenance,” as well as “Zinn and the Art of Triathlon Bikes” and “Zinn’s Cycling Primer: Maintenance Tips and Skill Building for Cyclists.”Zinn’s regular column is devoted to addressing readers’ technical questions about bikes, their care and feeding and how we as riders can use them as comfortably and efficiently as possible. Zinn’s column appears here each Tuesday.

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Lennard Zinn

Lennard Zinn

Our longtime technical writer joined VeloNews in 1987. He is also a framebuilder, a former U.S. National Team rider, and author of many bicycle books, including Zinn and the Art of Mountain Bike Maintenance and Zinn and the Art of Road Bike Maintenance, as well as Zinn and the Art of Triathlon Bikes and Zinn's Cycling Primer: Maintenance Tips and Skill Building for Cyclists. He holds a Bachelor’s degree in physics from Colorado College. Readers can send brief technical questions to Ask LZ.

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