Who wants to run a marathon in a diaper? That’s what you’re potentially doing if you wear bike shorts to run an Ironman.
The debate rages on about using bike shorts versus triathlon-specific shorts for triathlons. Sure, you have some extra padding for a 112-mile bike ride, but that extra padding takes extra time to dry out after the swim and any sweat from the bike ride will collect in that pad as well, so when you hit the run you’ll be contending with jelly legs AND diaper rash.
As you can see, each has a plus and a minus. Bike shorts are a great tool for long training rides to save your rump, but if you don’t train in clothes you will race in, you may be in for a rude surprise when you exit T2 and realize you had less padding for 112 miles. Ouch.
Consider using bike shorts for the winter training rides. Most of us have to relegate ourselves to the basement spinning on the trainer and need all the help we can get to get through hours of riding nowhere. A sore backside adds to the despair of riding a trainer all winter. Some triathlon shorts are a little more delicate and riding for hours a week can deteriorate them and result in spending more money to keep up your tri short supply, or you’re riding in threadbare shorts exposing your assets. Take into account the harsh chemicals in pools as well and avoid using tri shorts while training in pools.
In summary, you can survive triathlons in bike shorts. But, if you are getting more competitive and challenging yourself with larger distances, triathlon-specific shorts are the way to go. You won’t fight extra padding on the swim, and you may sacrifice some comfort on the bike, but it will pay for itself over the run when you aren’t fighting a diaper and chafing your way to the finish line.