To run you only need shoes; to swim, maybe a pair of goggles. A good bicycle, however, probably costs more than your first car. "You probably don't need a whole new bike for your first tri, but every upgrade gives an amateur triathlete a greater benefit," says Chris Vassiliades, a USA Triathlon-certified coach and owner of Element Multisport in Chicago.

Here's what to grab and what to skip when you visit the bike shop.

Do I need a triathlon bike?
Not for your first race. Triathlon frames have a steeper seat post angle relative to the ground-as much as 80 degrees compared to around 73 degrees on a road bike. That change, even if it sounds small, allows you to engage your quads more while pedaling and save your hamstrings and glutes for the run.

I have an old Huffy, and this is my first triathlon. Is it OK to ride?
According USA Triathlon's official rules, your ride must have a brake on each wheel, and a free-wheeling mechanism on the crank so you can roll forward while the pedals remain stationary. So many fixed-gear bicycles are out, along with bikes that you can only brake by back pedaling. Otherwise, you're probably good to go. If you have a mountain bike, Vassiliades recommends simply swapping out your knobby tires for road racing slicks.

How do I know if my bike is the right size?
With both feet on the ground, the crossbar should come up to an inch or so below your crotch. When seated, your leg should have a slight bend when the pedal is at its lowest point. There are also several crucial adjustments you can make all over your bike to put you in the most biomechanically efficient riding position-find out morehere.

What about clip-on aero bars? Do I need them? How do they work?
Triathlons have strict rules about maintaining three bike lengths of distance between you and other riders unless you're passing. "That means no drafting, so an aerodynamic position is essential," says Vassiliades. To help you tuck into that Tron lightcyle pose, aero bars give you two narrowly positioned and forward-pointing posts for your hands to grab, and pads for your elbows to rest on. "Clip-on" aero bars bolt onto most road or mountain bike handlebars as a relatively inexpensive upgrade (sometimes less than $100) that make for a significantly easier ride.

Where should I keep my water?
Near your mouth, of course. "If you mount a standard, 24-ounce water bottle between your aero handles, it acts like the nose of a missile and gives you a more aerodynamic profile," says Vassiliades. Plus you'll have easy and quick access to your fluid, and you can even attach a drinking tube and bite valve so you won't have to tilt your head back to drink. If you're not plunking down for aero bars, you can mount a cage behind your seat (where wind resistance won't affect it) for around five bucks. Make sure to practice drinking while maintaining a steady speed.

Do I really need clip-in pedals? What are the different types of pedals and what should I look for?
Clip-in pedals-counterintuitively called "clipless" pedals, as opposed to the kind with "toe clips"-clamp into special bicycling shoes. Turning your crank and shoe into a single, solid unit allows you to keep transferring energy from your legs to the bike on the upstroke as well as the downstroke, and eases fatigue on your ankles and calves.

While you can just as easily ride in your running shoes with either toe clip or flat pedals, clipless pedals and shoes should be one of the first upgrades you make to your bike. "Look for shoes with a tab at the heel and velcro or elastic laces so you can pull them on in a hurry," says Vassiliades. Different brands of shoes will only match up with certain types of clipless pedals, so make sure you buy compatible models.

What do gloves help with? Do you really need them?
Gloves protect you from blisters and help sweaty palms keep a firm grip on the handlebars. But they're not absolutely necessary for races shorter than a half Ironman, says Vassiliades. Look for gloves with webbing between the fingers. That's not to help you swim, Aquaman-grab the webbing to pull off the gloves before your run.

My saddle hurts my junk. What's a good one?
Don't run or swim wearing heavily padded bicycling shorts. "That's going to feel like running in a diaper," says Vassiliades. Instead, pick up a pair of triathlon shorts with a light cushion in your sit spots.

For the saddle itself, the best seats have a split nose to allow maximum blood flow to your perineum. If that leaves you feeling wobbly (since most steering comes from your hips as you lean through turns), try a seat with a longer nose and an oval-shaped hole near the center to ease pressure, like the SLR SuperFlow 135-a Bicyclingmagazine Buyer's Guide pick.