Welcome to our Ask a Mechanic column where our expert mechanic Daniel Slusser answers your bike maintenance questions. If you have a question for Daniel, please post it on our Facebook Wall or e-mail Daniel directly at firstname.lastname@example.org.
Question: I have a brand new WTB Bronson TCS tire that I flatted on my first ride. It was a pinch flat that I got on a high-speed section of rocky trail. The tire was setup tubeless but the impact caused a tiny 2mm puncture right next to the bead and no matter how much sealant I put in the tire it won’t hold air. Is there a way I can save this tire? From: Kyle
Answer: Wow, you pinch flatted a tubeless tire!?! Kudos, my friend. You must have really been hauling the mail, or running far too low air pressure in your tire. Either way, you have something to be proud of, as this is a feat that is difficult to achieve.
To answer your question, there is an easy way to save your tire. Put a tube in it. There is no way to reliably patch a tire punctured near the bead. If the flat were somewhere else on the tire you would have a fighting chance at fixing it.
Although I know the advice I am about to offer on how to patch a tubeless tire will not help you in this instance, I offer it anyway to help the many others that have suffered punctures in more normal locations.
First you’ll need something we call a “boot.” This is not to be confused with a different word pronounced the same way (a homophone) by our northern neighbors meaning “nearby, or concerning a given subject.” No, the boot I am referring to is a small scrap of material that is used as a patch. This material could be made of any number of items. The important thing is that your chosen boot is somewhat flexible, yet does not stretch easily. Common boot materials include American paper currency, energy gel wrappers, old bicycle tire sidewall casing material, discarded bulletproof vests, etc. Keep in mind that the larger the hole, the stiffer the boot needs to be to patch it effectively.
Simply take some inner tube patch cement or tubular tire glue and apply a thin layer to the area of the tire to be booted or patched. Do the same to the boot. Let the glue glaze over and become tacky while remaining slightly viscous. Then press the two together while working out any bubbles that may have formed during application. Make sure the edge of the boot adheres to the tire around the entire circumference of the boot. If it does not, don’t fret. Just apply more glue to the edges and work them by pressing the boot down with your fingers until it fully seals. Give the whole assembly a few hours to cure and you will be back living comfortably in the modern era of tubeless tires in no time flat (pun fully intended).
Daniel Slusser is a professional bicycle mechanic with over ten years of experience. He holds a bachelor’s degree in business administration from HSU and a master’s degree in history from Cal Poly University. When he is not riding, wrenching, or writing he enjoys spending time with his wife and two children.