Ask Aaron: When Should Triathletes Replace Tires, Chains, Shoes?

Published May 5, 2011 10:47PM

When do I know it’s time to replace a pair of tires? I flatted recently and I’m concerned it will happen again.

Knowing when to replace worn-out gear can be tricky, since there typically isn’t a firm limit to the lifespan of a particular piece of gear. Here are some guidelines for when you should consider swapping your old stuff for new.

First, the rubber can simply wear away from the tire, leaving it with a flat surface contacting the road rather than a round surface. That flat surface prevents the tire from smoothly rolling through corners as it did when it was rounded. If enough material from the center of the tire is removed, the casing—the cloth backbone that gives the tire structure—eventually becomes exposed. When this happens, you will see thin threads starting to poke through the rubber. This leaves the tire vulnerable to puncture and ruins traction. Any tire with exposed threads is well past its expiration date and needs to be replaced.

Cuts are the other common cause of death for a bike tire. If you roll over a sharp object that tears a big hole in the casing, it creates a weak spot in the tire that allows road debris to poke through and puncture the tube. If your tire is gashed, either on the sidewall or on the tread, it needs to be replaced.

Tip to keep your tires fresh: Use another tire on the trainer. Riding rollers or a trainer greatly increases the wear and strips rubber away rapidly. Get a long-lasting tire such as the Continental Gatorskin or Specialized All Condition to use on the trainer.

As a chain stretches, not only does it interfere with shift quality, but it also grinds on the chainrings and cassette, thereby reducing their lifespan. Buy a chain checker, such as the ParkTool Chain Wear Indicator, to measure its stretch and prolong the life of your entire drivetrain. This tool eliminates the subjectivity often involved with changing old parts and provides a definitive upper limit for the wear life of a chain.

Tip to keep your drivetrain fresh: Change your chain! Spending a few bucks to regularly change your chain will preserve the more expensive components of your drivetrain.

There is no foolproof way to determine when a running shoe is worn out. As you put more miles on a pair, the EVA sole gradually degrades, which makes it difficult to perceive when the shoes need to be replaced. The best practice is to switch them too early, rather than waiting for them to break down and put extra wear on your legs.

Tracking the number of miles you put on a pair creates a useful upper limit. A pair of mid- to heavy-weight training shoes typically lasts 400-450 miles, a pair of lightweight trainers can be good for 350-400 and a pair of racing flats typically lasts for about 250-300. Some manufacturers use different materials or sole designs, which they say increases the wear life of their shoes, and if a pair still feels fresh under your feet once you have reached those rule-of-thumb numbers, you may not need to trash them.