In the documentary about the Titan Desert 2016, produced by Valentí Sanjuan, a surprising moment is shown in which a rider repairs a persistent puncture with duct tape. This clever resource allowed him to complete the last kilometers of one of the toughest stages of the race. Beyond being an anecdote, this scene reflects the importance of having quick and effective solutions in demanding competitions and long-distance routes.
On mountain bike rides, where rough terrain can test the durability of the equipment, duct tape can be a temporary solution for emergency repairs, such as fixing a damaged tire or securing a loose component until reaching the next support point. The same happens on long routes with road bikes, where any minor breakdown can compromise performance if you don't have the right tools at the moment.
When it comes to adventure cycling or extreme endurance events, improvisation can make the difference between abandoning a stage or reaching the finish line. That is why many cyclists, both mountain bike and road, include duct tape in their tool kit to solve unexpected problems and keep riding without wasting time. A simple accessory, but one that can save the day in the most demanding conditions.
An invention from World War II
The duct tape It is largely unknown in the field of sports, not many people carry it in their backpacks, but those who do, love and revere it. As you may know, it is an adhesive tape made of a mesh of strong fibers (the same concept as first aid bandages), usually polyethylene, and an extremely strong adhesive. If you have used it, you know it has a peculiar quality: it can be easily torn crosswise but is extremely resistant to tension (that is, lengthwise). This simple and humble invention was patented by Johnson & Johnson in 1942, during World War II, with the intention that soldiers could protect their ammunition from moisture. The U.S. Army immediately adopted this type of tape and the uses given to it were almost infinite. Without a doubt, it was the best testing ground for the product. Today, its distribution reaches all kinds of professional and recreational activities around the globe, to the point that extravagant annual contests are already organized to reward the most original use. 
Why you should carry it in your backpack
In the event of a blowout, it can be used to cover the inside of the tire. A broken spoke can be temporarily joined, enough to finish the route by the quickest way. It can fix a torn backpack or travel bag. Reinforce the union of any two pieces. On multi-day routes, it can be very useful if the bivouac tears for any reason. In short, it is a powerful multi-purpose ally to solve a technical or mechanical problem. It is one of those tools that force you to carry a backpack or a small saddlebag on your bike. They are not usually available in small sizes, and possibly a single roll will last your entire sporting life. The biggest use you will give it is to help your companions with this or that incident or repair. For all these reasons, it is always advisable to keep it close, especially when you are going to spend many hours on the bike on routes full of inconveniences and technical challenges.