How to Accurately Measure Saddle Position – Part II – Fore/Aft

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To follow up on how to consistently reproduce your saddle position time after time, I would be remiss if I did not address fore/aft position.  Saddle position, much like your handlebar position, is measured in two planes.  The X (horizontal) and Y (vertical).  Both these measures are taken from one central landmark on the bike, your bottom bracket.

Here are two way to accurately measure your fore/aft position and make documenting and reproducing your saddle position reliable and consistent.

The first method is with a traditional weighted line.  Here you will have your bike off the trainer with the line going right over the tip of the saddle. The line should be long enough to drop past the chainstays and bottom bracket.

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PRO TIP:  You will want to tip your bike slightly toward you to allow the weighted line to hang freely without interference from the frame or cables.  Cyclocross and Mountain Bikes in particular tend to have wider top tubes and stays which can interfere with the path of your line.

Take a ruler or tape measure and align it with the center of your bottom bracket.  Let the weighted line settle to a consistent point.

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There is your fore/aft position! 9.1 cm is the example used in this post.

The second method will give you the same result without having to remove the bike from the trainer.  Most people I know will not pass up the opportunity to play with lasers.  Cats like lasers, kids like lasers, DIY homeowners like lasers, and bike fitters are no different.  We love lasers! and use them any time we can to get an accurate straight line assessment.

Line up your laser with the center of your bottom bracket.  I have made it a habit of using the non drive side because there are many cranks without a good center point on the drive side.

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Take your tape measure and line it up on the tip of the saddle

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That’s it!  9.1cm is the number in this example.

You are all set to get your saddle dialed in after any maintenance, changes in seatpost, and to replicate your position on a similar style bike with the same saddle.

 

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How to Accurately Measure and Reproduce Your Bike Saddle Position Time After Time – Part I – Saddle Height

 

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I am frequently asked when performing bike fits how to measure the saddle height and reproduce the fit if the seat post is moved or taken off.  Here is a reliable way to reproduce bike saddle height or match saddle height bike to bike for a similar style bike (i.e.-road bike to road bike or cyclocross to cyclocross bike) with the same saddle.  If two saddles are different, the seat heights may not directly transfer.  Each saddle brand will have a different resting spot for your sit bones and the total length of the saddle may be different as well requiring some minor adjustments to the position.

A few easy steps will have you confidently positioning your saddle time after time.

1.  Measure the length of your saddle

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2.  Place a piece of painter’s tape with the back edge at the midpoint of the saddle.  For example, this saddle is 28 cm long.  Place the back edge of the tape at the 14 cm mark.

 

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3.  Measure from the center of the bottom bracket to the back edge of the painters tape.  Some modern cranks do not have a nice central crank bolt to measure from.  In this case, pick a landmark on the drive side that is most central and use that each time.

 

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4.  You will want your saddle height to hit the back edge of the painters tape.  For this example the target number is 74 cm.

 

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So fear not the dreaded move of your seat post and move that seat post to put in your car or to perform the necessary maintenance to keep your seat post from seizing up in the frame.  Once you have your saddle height dialed, you can always wrap a piece of electrical tape just above the seat collar for an easy reminder of saddle height.

Ride on and visit ptbikefitllc.com often