Need a Bike? What is your Bike Size?

With the Ironman 70.3 Philippines in a few months, excited first time triathletes prepare for their biggest race this year.

Swim training is the most difficult for many. Not many of us swam when we were younger and some just learned how to swim. The first thing we need to start our swim training is to get a swim coach. We will also need basic swim equipment to help us practice better. A good pair of training or pool goggles and open water or race goggles are a necessity. Swim trunks or tri shorts and swim caps are required for most swimming pools and a few swimmers invest in pool buoys, paddles or kick boards to enhance their training.

Runners need only a good pair of running shoes. Although local running stores can easily help you with the right pair, many still resort to trial and error.

Cycling, on the other hand, is the most complicated. Finding the right gear is a challenge as even professional cyclists experiment on their equipment. I learned to bike when I was in high school and never realized it was this complicated.

For those joining the Ironman, road or tri bikes are required. I have searched online for the most comprehensive bike measurements needed prior to buying your first bike and became more confused since most recommendations are just estimates.

Body measurements are needed to arrive at the right estimate.

1. Inseam/ Inside Leg Length. These are taken with your back against the wall and standing barefoot. Measure from the floor up to the part where your measuring tape touches your crotch.

2. Trunk Length. From the top of your inseam, measure to the top of your sternum at the point where both clavicles meet in the middle of your chest.

3. Arm Length. This is measured from the hand (clenched fist) holding a round object to your shoulder joint (bony protrusion above the shoulders).

Bike measurements or geometry estimates from the body measurements taken.

1. Frame Size. Usually provided by manufacturers measured from center of bottom bracket to either center of top tube or top of seat tube. Estimated from Inseam x 0.65.

2. Top Tube Length. Measured using traditional (non-sloping) frames. Sloping frames are provided with effective top tube measurements by manufacturers. Estimated from trunk length + 2-3cm.

3. Saddle Height. Measured from center of bottom bracket to top of central part of saddle. Estimated from Inseam x 0.885.

4. Crank Length. Normally 170mm but may vary depending on rider height and riding style. Recent data suggest using shorter cranks for Time trials or Triathlon events.

5. Handlebar Measurements. Width usually 42cm depending on shoulder width and riding style. Sprinters use wider bars while Climbers use narrow bars. Drop, reach and shape of handlebars depend on rider preference and style.

6. Head Stem Length. Depending on riding style, stem length range from 60mm to 140mm or longer. Estimated from Arm length x 0.203. A rough guide is to look at the front hubs while riding on the drops or hoods (conflicting data regarding exact riding location). The handlebars should occlude the front hubs while assuming this position.

These are just basic measurement estimates that cyclist need to consider prior to purchasing or experimenting  with new equipment. Many factors need to be considered when experimenting with bike settings like comfort and riding style. Aggressive riders prefer to be more aerodynamic while some riders prefer to be more comfortable during their rides. Materials used for each equipment are significant for the weight-conscious cyclist. Carbon and titanium parts are lighter and more expensive than aluminum or steel parts. These do not necessarily relate to better performance.

Recently, I made small changes to my road bike setup which made very significant changes in performance. I changed my stem from 110mm to 120mm with a -6 degree rise and noticed major improvements. I always train with a heart monitor to check performance and noted that my heart rate was lower by at least 5-10 percent immediately after changing stems. These findings are consistent as I regularly check my training log for heart rate changes on the same course and intensity.

These are my exact road bike specifications.

Frame: Scott Speedster S20 aluminum with Scott carbon forks (Size: Medium/ TT: 54.5)

Stem: FSA OS150 120mm +/- 6 degrees

Handlebars: Scott Road Anatomic 42mm

Drivetrain: Shimano Ultegra

Cassette: Shimano Ultegra 11-25

Crankset: Shimano Ultegra 53/39 170mm cranks

Brakes: Shimano Ultegra

Pedals: Speedplay Zero Chromoly

Saddle: Fi’zi:k Arione Versus

Seatpost: Scott carbon/ alloy

Wheelset: Fulcrum Racing 7

Tires: Vredestein Fortezza TriComp 700x23

Bottle Cage: Lezyne cages

Computer: Cateye Strada Wireless

Cadence sensor: Garmin

Time Trial or Triathlon Bikes are a bit more complicated. No exact recommendations are published. Mountain bikes also have different recommendations.

(click to enlarge)