BiSaddle ShapeShifter EXT Installation Instructions

This saddle does it all--we'll help you install!

Please read the instructions thoroughly before attempting to install or ride your BiSaddle. If in doubt, please consult your local BikeFit Professional. While we do talk about saddle height and position in our blogs, the best setup is established through working with a BikeFit Pro.

This instruction sheet is intended for adjustment and measurement without using an old saddle.  If you’re comparing the width of your old seat to the BiSaddle ShapeShifter EXT, it is best to lay one saddle on the other with the widest point of both seats matching up to get an “apples to apples” comparison.

If you prefer, you can download our instructions.  You can also skip straight to the videos setup tutorials.

get started

Start From the Beginning

Record measurements and measure sit bones.

Saddle Width Setup

Adjust the width (front and rear) to find your custom fit.

Rounding and Flattening Wedges

Change the shape of your BiSaddle

Rear Water Bottle Mount

Install the included tri-specific rear water bottle mount.

Step 1: Record Measurements

Before removing your old saddle, be sure to record the two measurements below.

1 a.) Saddle Height

Measure from the top of the saddle to the center of the bottom bracket.

1 b.) Saddle to Handlebars

Measure from the widest point of the saddle to the center of the handlebars.

Record these two measurements and remove your old saddle.  These points will be used for installing the BiSaddle.


Step 2: measure your sit bones

Obtaining a width measurement for your sit bones (ischial tuberosities) can be useful for establishing a starting rear saddle width.  You can acquire this measurement at home using very simple tools and just a few minutes of your time.  Always let comfort be your guide.  Even though your sit bones may have a certain width, you still may like the saddle in narrow or wider position.

Tools Needed:


Crayons or Chalk

Ruler or Tape Measure

Hard, Flat Sitting Surface

Place a piece of clean cardboard onto a hard surface.  While sitting pull yourself firmly down on to it. This will leave impressions of your sit bones in the cardboard.  Be sure to sit upright and do not wear thick padded clothing.


Use a dark-colored crayon to rub across the surface of the cardboard (using the side of the crayon with the paper sleeve removed).  This will reveal your sit bone indentations.

Mark the center of each indentation.

Use a ruler or tape measure to determine the distance (in millimeters) between the center of the sit bones.

Most people add 1 to 4 cm(10 – 40mm) to this width to set the rear saddle width.

Step 3: setting up saddle width

Every BiSaddle ShapeShifter leaves our factory with a neutral position that works well for a variety of people (approximately 53mm front width, 145mm rear width). If you’re new to BiSaddle and not sure what you want or need, try this setting first. If you have experience with another saddle and know of specific measurements that you’d like, feel free to adjust to those settings.

In general, most people prefer a rear width of the saddle that’s equal or slightly greater (1cm – 4cm) than their sit bones for comfort and support.

Rear width adjustment range: 130 – 185mm.

The front width of your BiSaddle is largely up to personal preference. A wider front typically results in better blood flow and/or reduction of genital numbness.  If it’s too wide, however, it can cause rubbing or chafing of your inner thighs. We suggest that you set the front of the seat as wide as possible without chafing.  You can check the width of your saddle using a tape measure or Vernier caliper.

Front width adjustment range: 40 – 75mm.

Please consider your local BikeFit Pro for help finding your saddle settings.

To adjust the BiSaddle width, simply loosen (but don’t remove) the bottom bolts using the supplied Allen wrench. Adjust the seating pads to your desired width, and begin to tighten the bolts slowly.

We encourage you to double check that both sides are adjusted correctly several times before fully tightening the bolts.

Max bolt torque is 26 inch/lb or 3.0 Nm.

Carbon Rail Torque Specs: 6-8Nm for 2-bolt, 9-10Nm for single bolt.


Step 4: Profile wedges

Your BiSaddle ShapeShifter includes two sets of angled profile ie wedges. These can be installed between the base of the saddle and the two seating pads, to change the shape across the saddle top – making it either flatter or more rounded.

Wedge Screws: Longer screws included in the saddle package are required for wedge installation.

Rounding Wedge: front bolts 14mm, rear bolts 20mm.

Flattening Wedge: front bolts 16mm, rear bolts 20mm.

*Wedges will slightly reduce the amount of front adjustability.

Please consider your local BikeFit Pro for help finding your optimal saddle settings.

Wedge Installation


To install the wedges, remove the four bolts from the bottom of the saddle.  NOTE: The REAR bolts are slightly longer than the front bolts.


Place the wedge on the saddle frame, ensuring that it is properly aligned.

Press down so alignment knobs can engage frame.


Press down on the rear of the wedge to snap it into the frame.


The tabs will align to the groove in the cut out of the saddle frame.


Replace the bolts and washers. Use the longest set in the back and the mid-length set on the front. Your shortest set will be left over when using wedges. Adjust as needed.

MAX torque 25 in/lbs or 2.8 NM

Wedge Installation Videos

Step 5: Install adjusted bisaddle

Install the BiSaddle and lightly tighten your seat post bolts, while still allowing for some movement and adjustments (do NOT sit on the saddle or ride the bike yet).

Install the BiSaddle and lightly tighten your seat post bolts, while still allowing for some movement and adjustments (do NOT sit on the saddle or ride the bike yet).

To set the height, simply replicate the height you measured on your old saddle. You may also want to adjust the tilt of the saddle top. We suggest starting with the top of the saddle flat, or slightly tilted downwards.


Bring the necessary wrenches on your first few rides, as some small tweaks may be necessary to get the position 100% dialed in. Often times a small adjustment in height, tilt, or fore-aft can make a big difference in comfort.  Also feel free to experiment with the saddle width, always making sure to carefully adjust it and properly tighten the bolts before riding again.

Always let comfort be your guide!

rear bracket instalation

Optional purchase from BiSaddle

bisaddle setup video library

All you need to install your setup your new BiSaddle

BiSaddle ShapeShifter EXT

BikeFit Special Edition
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