CHOOSING THE BIKE

By Nenad Rodic,
posted 04/05

When choosing a bike it is important to have several things in mind:


1) What kind of event are you going to use the bike for? Ultra-distance racing places emphasis on comfort, and short distance on aerodynamics.
2) What type of rider you are? If you are flexible and can easily acquire new movement, you should go with the fastest, most aerodynamic machine you can find. If you are comfortable with only one type of geometry, then…?
3) Material? Carbon is definitely the best compromise between comfort, strength and value. If you seek comfort go with titanium. If you seek value go with aluminum. If you seek class go with hand-made steel.
4) Where you live? If you live in a mountainous area, you need to choose road geometry and a very light set up. If you live in the flatlands a Time-Trial bike will suffice.
5) Price?Ideally you want to have two bikes: one for every day training and road racing, and one for triathlon (time trial) training and racing. If this is not possible, you need to compromise and put together a bike that is comfortable enough for everyday training, yet suitable for time trials and triathlon races.


BIKE FIT


Every bike fit must start with some kind of leg measurement. Usually the inseam is measured. Stand against the wall with your feet pedal width apart. Pull a big hard cover book tightly up to your crotch. Step over the book and mark the spot on the wall. Measure the distance to the floor. This is your inseam. Multiply this value by 0.883 (Le Mond’s formula). The result value is your approximate seat height (center of bottom bracket (BB) to the top of the saddle-spot where you sit) photo 1. Your real seat height will depend on few other factors. Back to top                                                  

1) Add a centimeter or two for cleat adjustment. (measure the size of: your cleats; the adaptor (if there is one); and the sole of the shoe)
2) If you train a lot (300+ miles a week, you definitely don’t want you saddle height to be too high. Start with the exact value or little lower of what the formula prescribes.
3) You always ride forward position (more than 74 degree seat tube angle). You might want to try 5-millimeter higher saddle.
4) Personal preference. Do not go over one and a half centimeters of what the formula says. You will get hurt, I can promise you that.

Photo shows the proper way to measure the saddle height. Measure form the center of the bottom bracket to the top of the saddle (spot where you sit). Back to top

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Another helpful method is to sit on the saddle, put your heals (with shoes) on top of the pedals and pedal backwards (photo 2). Have a friend look at you and tell you whether your hips are rocking from side to side. If they do, your seat is too high.


Saddle position is a matter of preference. You can have your seat all the way back or all the way forward.

Some world class cyclists like Bobby Julich, for example, ride 73 degree seat tube angle bikes with the seat all the way forward which makes the seat angle 75 degrees in reality. For triathlon purposes (time trialing) you want to be slightly forward 75-76 degree. Back to top

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For triathlon purposes (time trialing) you want to be slightly forward 75-76 degree. The current UCI rule is that the vertical line from the tip of the seat has to be at least five centimeters behind the bottom bracket. There is a reason for this rule and I recommend that you set you triathlon bike exactly like this (5 cm behind the BB). Back to top 1
Measure the saddle height again (from the center of BB to the top of the saddle (spot where you sit). A sure way to make everything right is to drop the plumb line from your knee down. The vertical line should drop at the pedal axle when cranks are parallel to the ground. Back to top 1

Most people will recommend you set the seat height first and then play with fore and aft seat position. I suggest setting the seat 5 cm behind the BB to insure the maximum power output in time trials. If you’re setting the road bike position go with the first option (seat height first and fore/aft seat adjustment second)
This was all very easy. Now the problems arise. Are you setting up a road bike or a time trial bike? Do you only have one bike?
I’ll start with road bikes. Included is the sizing chart that will help you determine the right frame size you need to acquire. It is based on Le Mond’s formula. Back to top

INSEAM
FRAME SIZE* SADDLE HEIGHT **
66 42.9 58.3
67.3 43.8 59.4
68.6 44.6 60.6
69.9 45.4 61.7
71.1 46.2 62.8
72.4 47.1 63.9
73.7 47.9 65
74.9 48.7 66.2
76.2 49.5 67.3
77.5 50.4 68.4
78.7 51.2 69.5
80 52 70.6
81.3 52.8 71.8
82.6 53.7 72.9
83.8 54.5 74
85.1 55.3 75.1
86.4 56.1 76.3
87.6 57.8 77.4
88.9 58.2 78.5
90.2 58.6 79.6
91.4 59.4 80.7
92.7 60.3 81.9
94 61.1 83
95.3 62 84.1

*Frame is usually measured form the bottom bracket center to the top of the seat tube. Some frames are measured differently. Consult the geometry chart on the manufacturers web site or a catalog.
** Distance form the bottom bracket center to the spot on the saddle where you sit.

Today, many manufacturers make only a few sizes: small, medium, and large, for example. If this is the case, consult the professional people in your local bike store. This is especially important if you’re in between the sizes recommended by the manufacturer.
The next issue is the upper body extension. Generally speaking, you want to be relaxed and extended on a road bike with most of the weight in the saddle. On a time trial bike, you want your weight to be evenly distributed between the elbow pads and the saddle, which means that the overall length of the top tube/stem combo will be much shorter (5-8%). One thing that should not differ much is the distance form the tip of the saddle to the middle of the handlebar. On a road bike, handlebars will be higher and farther, while the TT bars will be lower and closer. One useful tool in finding a proper fit is the LOOK ergo stem (www.veltecsports.com). Back to top


Difference between road and TT position shown in next two photos

Time trial bike. Even though I am six one and with the inseam of 89 cm, I ride medium Giant with the seat tube length of 56 cm with a size 5 seat post (very long) and the top tube of 55 cm. The idea is for the bike to be short enough for me to transfer weight to the elbow pads and eliminate the stress on my back while maintaining aerodynamic position. Interesting fact is that all riders of former Team ONCE rode small Giants, even the six foot guys. Team manager Manolo Saiz wanted to have the shortest possible length of the whole team for the team TT by riding the smallest and shortest bikes. Strategy worked since they won the Team TT two years in a row in Le Tour de France. 1
Road bike. Body is more extended, with most of the weight on the saddle. Arms are slightly bent. Hip angle is more open than in the TT position. 1

SUMMARY: measure the inseam and choose the proper size of frame. Set the
saddle height according to Le Mond formula. Put the bike on the trainer and get a few different size stems or a LOOK Ergo stem. Play with the handlebar height and extension for about one hour while riding on a trainer. When you find a position that feels good, take the bike for a real ride (2+ hours). You should feel comfortable and powerful. For TT bike move the seat forward up to two centimeters, drop the bars down (2-4 cm) and bring them in (2-4 cm). Again, get on a trainer and play with it until you find the right position. Be aero but powerful and pain-free. Take it out for a real ride.
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By Nenad Rodic, founder of Triathlonplace.com