Bike Set Up Instructions
For
Road Riding and Triathlons

This paper helps explain how to set up a bike for general road riding then how to modify the position for riding in a aero position using tri bars. The paper also highlights the compromises that need to be considered when moving away from a road to an aero riding position. Much of the information comes from experienced cyclist and published articles which seem to make logical sense to me. I hope you find it helpful.

Eric Wilcock

Neutral Road Riding/Racing Position

  1. Preparation
    1. Gather together the following equipment:
      • Pen & paper
      • Calculator
      • Tape measure
      • Sprit level
      • Plumb line
      • 4mm, 5mm, 6mm Allan keys
      • Turbo trainer
      • Large mirror and/or assistant
    2. Find a level floor preferably with a hard surface.
    3. Place your bike in the turbo trainer and set the bike level by measuring the distance from the floor to the centre of the rear wheel spindle (assuming both wheels are of the same size). Pack up the front wheel so the spindle height from the floor equals that of the rear. Do not use a sprit level on the top tube as they are a reliable way to set the bike level.
    4. Make a note/sketch of all the key dimensions of the initial bike set up using references that will allow you to re-establish this road/racing position easily.
  2. Crank Length
    1. Measure your inside leg length in mm (to the floor in bare feet).
    2. Multiply your inside leg measurement by 0.2 to get the correct nominal crank length.
    3. Fit cranks that are within +/- 2.5mm of the nominal value in 2.2. Note: Powerful riders who cycle with a low average cadence (< 85 rpm) tend to select cranks that are on the plus side of the nominal value. Shorter cranks encourage riders to cycle at higher cadences. It is generally accepted that average cadences of 90 rpm or higher is more efficient than pushing big gears at a low cadence. However, cycling at higher cadences is more demanding on the cardio vascular system and pedalling technique.
  3. Seat Level
    1. Place the spirit level on the top of the saddle and set level.
  4. Shoe Cleats.
    1. Sit on the bike and clip in.
    2. Set shoe cleats so that the ball of your foot is over the pedal spindle.
  5. Seat Height
    1. Wearing your cycling shorts and shoes sit on your bike in your natural road riding position, with hands on the top of the brakehoods.
    2. Unclip one foot and with this leg locked out straight adjust the seat height so your heel just scrapes the platform of the pedal at is bottom most position. Take care to keep your hips level.
  6. Seat Fore and Aft Position
    1. Sit on your bike, clip into your pedals adopt your natural road riding position with hands on top of the brakehoods.
    2. Place the crank arms in the horizontal position with your foot level with the floor.
    3. Drop the plumb line down from the front of your knee and adjust seat fore and aft position until the plumb line bisects the pedal spindle. Take care to sit in the saddle as you would if you were riding your bike. Do not slide forward and back in the saddle or drop and raise your heel to bring the knee to the correct position, do it by adjusting the saddle!
    4. Recheck your seat height and adjust if necessary.
    5. Recheck the seat fore and aft position if you adjusted your seat height.
  7. Drop Handle Bars Fore and Aft Position
    1. Get off the bike and stand at the side.
    2. With your forearm horizontal place your elbow on the nose the saddle with finger tips pointing towards the front of the bike.
    3. Check that the tip of your longest finger is three to four finger widths from centreline of the handlebar as it passes through the stem. Change the stem for one of the correct length if not. Note: The distance of the handlebar from the seat is a down to personal preference and this way of setting the handlebar fore and aft position only provides a start position from which you can fine tune to your riding style. Hence it is a good idea to borrow a stem of the length suggested by this method first before buying. However beware, stem length affects the way the bike handles. Hence, it is not wise to fit extremely long (>>120mm) or short stems (<<80mm) to correct for a frame that is too small or large for you. If in doubt about frame sizes seek advice from a reputable cycle shop or knowledgeable cyclist.
  8. Dropped Handlebars Rotation & Brake Hood Position.
    1. Sit on the bike and adjust the handlebar rotation so they feel comfortable when riding on the tops, the brakehoods and the drops. Note: The top of the brakehoods should be level or slightly tipped up at the front. The tips of the brake levers should not be below the bottom off the bars. Brake levers should be within reach when on the drops.
  9. Dropped Handlebar Height
    1. Sitting on your bike with your hands on the brake hoods adjust your handle bar height until your hip angle approximates to 90 degrees. Note: Hip angle is shown in the sketch to the right. It is created by imagining a line from your pedal spindle in the down position to your hip and from your hip to your shoulder. In this position you should feel well balanced with not to much weight being taken through your hands.
  10. Record Bike Set Up Key Positions

    Make a note/sketch of all the key dimensions you have just set using references that will allow you to re-establish this road/racing position easily.

  11. Experiment

Ride in your new position for several miles to give your muscles and the neurological connections to them time to adapt. Consider tweaking the position to suit your preferences if you wish but make any changes gradual (just few millimetres at a time) and allow time for your body to adapt to the changes. Whatever the final position you arrive at make sure it does not to depart to far from the 90-degree hip angle shown in the sketch above.

Aero-Position

Each of the three riders represented on the right are in positions appropriate for Time Trialling / Triathlons. Which one you adopt depends on how much you are willing to spend, comprise comfort and safety for the sake of speed and efficiency. We will come back to these issues later when we consider the advantages and disadvantages of adopting an aggressive aero position using a Time Trial / Tri specific bike compared to a more neutral riding position using a road/race bike.

The aero position with its low frontal area should not be created by making the 90 degree hip angle (established in the previous section for a neutral road/race riding position) more acute. Instead the aero position is created by rotating the rider about the bottom bracket. There are several ways of doing this, namely: pushing the seat further forward, by sitting further forward on the seat (“sitting on the rivet”), or by using a bike frame with a steeper seat tube angle (which effectively pushes the bottom bracket back further under the rider). How to modify the neutral road riding/racing position established in the previous section is explained below.

  1. Fitting Tri Bars
    1. Fit the tri bars to your bike and adjust so they are at their lowest possible position. Ensure this position places the bottom edge of your hands level or slightly above your elbows when in the aero-position. Note: Some riders (even professionals) ride with their hands lower than their elbows but this is not the most aero dymanic position.
    2. If converting a road bike for Time Trialing then the front of the bike (relative to the saddle height) may not be low enough to achieve a good aero position. Special stems (such as the Look “Ergo Stem”, see picture insert) are available that allow the handlebars to be mounted lower than a traditional stem.
  2. Seat Fore and Aft Position
    1. Sit on the bike and clip in and adopt the aero position.
    2. Adjust the fore and aft position of the seat in order to preserve the 90-degree hip angle. Note: The position of the knee may now be in front of the pedal spindle when the crank arms are in the horizontal position, this is ok.
    3. Check and readjust the seat height as before. Note: Pushing the seat forward will require you lift seat to maintain the correct seat height over the pedals.
    4. If you can’t achieve the 90 degree hip angle by pushing the seat forward then raise the tri bars so you can. Note: Special ‘fast forward‘cranked seat posts are available that allow the seat to be placed much further forward then that achievable with a regular seat post. Take care not to push the nose of the saddle past the centre line of the bottom bracket. Such a position would be too extreme and will adversely affect rider comfort and the safe handling of the bike.
  3. Tri Bar Fore and Aft Position
    1. Sit on the bike and adopt the aero position.
    2. Set the fore and aft position of the tri bars so that the angle created by drawing a line from your hip to your shoulder and from your shoulder to your elbow is 90 degrees. A different length stem may be required to achieve this fit.

      Note: This 90 degree angle between your back and upper arm allows you to support your body weight by your skeletal structure. Departing from this angle places more work on your shoulder and arm muscles and so is not efficient.

    3. Set the fore and aft position of the arm rests so they are on the fleshy part of your forearm.
    4. Check that any adjustments to the tri bar fore and aft position has not changed your 90 degree hip angle. If it has then readjust the tri bar height or seat fore and aft position or a combination of the two.
    5. Check the position of the tri bar grips relative to the tri bar arm pads also create an angle between your upper arms and your forearms of about 90 degrees. If it is the bottom of your hands should be above your elbows.
  4. Tri Bar Width Position
    1. Sit on the bike and adopt the aero position.
    2. Set the width of the arm pads so your elbows are as close together as comfort allows. Note: Arms close together improves the aero dynamics but restricts breathing. Experiment to find your preferred width position.
  5. Record Bike Set Up Key Positions
  6. Experiment

    Try riding in your new position for several miles. Consider tweaking it to suit your preferences. Pointing the nose of the saddle down slightly may improve the comfort of an aggressive aero position. Consider the trade-offs between the high torque neutral road/race position and the aero dynamic riding position. A hilly TT course would favour a less aggressive position. What ever position you finally decide upon take care that it does not to depart to far from the 90-degree hip and shoulder angles shown in the sketch above.

    The following section list the advantages and disadvantages of an departing from the neutral riding position on a road/race bike to a much more aggressive aero riding position using a Time Trial specific bike that has a steep seat angle, low front end, integrated tri bars with bar end gear shifters.

Advantages of the Aero Position

Disadvantages of the Aero Position: