Triathlon and Road Bike Research

So I am tempted to do a triathlon if I see one come up.

Wikipedia and a distance converter helped out.

Sprint Distance- USA Triathlon, the main international race distances are
750 m/.466 mile swim
20 km/12.42 mile bike
5 km/3.1 mile run

Intermediate (or Standard) distance, commonly referred to as "Olympic distance"
1.5 km/.93 mile swim
40 km/24.85 mile ride
10 km/6.21 mile run

the Long Course (Half Ironman)
1.9 km/1.18 mile swim --I've done one mile in about an hour
90 km/55.92 mile ride
21.1 km/13.11 mile run --I've done this in about 2 hours

Ultra Distance; the most recognized branded Ultra Distance is the Ironman triathlon.
3.8 km/2.36 mile swim,
180 km/111.85 mile ride --I did 100 miles in under 10 hours with many long breaks on a poorly geared bike with aero bars
and a marathon: 42.2 km/26.22 mile run

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I'm already looking at good bike configurations.
Here is the start of a relatively comprehensive summary of the highlights. It is a work in progress. Please comment with tips for order, phrasing, conciseness, relevance, etc.

You need a bike that fits you. You should be able to straddle the bike while in front of the seat and have about an inch of clearance.

Get a bike that weighs under 30 lbs (including aero bars). Road bikes generally range from 35 lbs to 14 lbs. The more total weight you carry, the slower you are when riding up hills. Lance Armstrong is 5'10", weighs about 155 lbs, and rides a 14 lb bike with some water for a total weight of around 172 lbs. (The Tour De France set a minimum weight limit at 14 lbs to prevent the race from costing more than it does already. Each rider uses several bikes each day of the multi-day race. Bikes in the Tour De France used to cost about $600 to manufacture 30 years ago. Now, with all the lightweight and aerodynamic components, some bikes range in the $5,000 range.)

Steel bikes are usually heavier than aluminum which is heavier than carbon fiber bikes. Generally the lighter the bike, the more it will cost. Aluminum is more expensive than steel and carbon fiber is more expensive than both. However, there are new aluminum bikes that are more expensive than steel ones but actually weigh more than the steel frames. Aluminum and carbon fiber bikes generally need thicker parts on the frame because they can not handle the side to side torque as well as steel and other metals, like magnesium, another lightweight metal popular in older racing bikes.

There are some old composite metal racing bikes that are only about 25 lbs and lighter than some modern aluminum bikes. Walmart's GMC Denali road bike is aluminum and weighs around 30 lbs. It has low quality parts that make taking the tires off difficult. It's not a great buy.


Parts that Matter

The more teeth the the main crank gear where the petals are, combined with as few teeth as possible on the rear wheel gives you the maximum potential speed of the bike.
The main gear for racers in the Tour De France are 55 teeth on one of their bikes and 53 on another of their bikes. Unless you have calf muscles like theirs, the standard 52 tooth gear is fine.

The rear wheel should have a small gear with 11 or 12 teeth and a rear large gear with 25 to 28 teeth. Competitive racers tend to have a smaller range of teeth in the rear cassette so they can get a more precise ratio. An 8 speed bike uses a more durable chain and doesn't need to be as finely tuned as a 9 or 10 speed bike.

The main crank can have as few as 50 teeth if you have 11 teeth on the back. If you have 12 or more teeth as your smallest gear on the back wheel, you will want 52 or more teeth on the main gear.

Many road bikes from the 80s have a main crank (the gears on the pedals) of 52 teeth and 39 teeth with 14-28 gears in the back or 52 and 42 teeth on the main crank and 14-30 teeth on the back. Notice how both bikes have the same gear ratios for their highest and lowest gears. 52-14 on both and 39-28 for the lowest gear on on and 42-30 for the lowest gear on the other. Those last two ratios are the same. You can go to the site.

Some road bikes will have three gears on the main crank. Most keep it down to two to save on a tiny bit of weight and reduce the need for an accurate shift on three gears vs two. This is usually fine since the smallest crank is usually not used in a race.


The Differences Between a Road Bike and a Tri-Bike

A road bike is built for fast handling and rapid acceleration.
The shifters are in front in stead of to the sides.
There are elbow pads on a tri bike so less weight in on your legs which are needed for the run.
The seat is more on top of the crank/pedals.
The downtube may be aero-shaped.
The tri bike will weigh a little more.