The label on the box said the saddle was designed for women. That label did a lot of work. It had to stand in for sit bone width, pelvic rotation, riding position, and pressure distribution. The problem is that sit bone width varies enough among adult women that a single fixed shape cannot fit most riders. A saddle that is only a few millimeters too narrow shifts your weight off bone and onto soft tissue. Bisaddle replaces that demographic guess with a geometry problem. A custom fit session solves the problem in one visit.
For decades, the bike industry treated comfort as a gender category. The real variable has always been the distance between your ischial tuberosities, the two bony points you sit on. That measurement is simple to take and has been used in orthopedics for decades. Saddle makers simply did not apply it to production. Instead they built a narrow racing shape for one average body, then softened it with foam and called it a women's model. That guaranteed a poor fit for anyone outside the midpoint.
The historical workaround started with wider seats
Early cycling saddles for women were wide and short. They matched upright riding positions and the clothing of the time. They were not built from sit bone measurements. They were built from practical constraints. When road racing became the dominant market, saddle design standardized around long, narrow, lightly padded shells. The wide seat disappeared because racers wanted light weight. Manufacturers applied that racing aesthetic to every saddle they sold.
That left women's saddle discomfort to be treated as a hygiene problem or a clothing problem. It took a long time for the conversation to move toward geometry. The tools already existed. A pressure pad or memory foam block can capture sit bone spacing in seconds. The delay was expensive: pain, numbness, skin damage, and years of riders trying different models without solving the measured problem.
Fixed widths ignored the one measurement that matters
Sit bone width is the center-to-center distance between the two points that should carry your weight. A saddle must be wide enough at the rear to hold both points with a small margin. Too narrow and you sink onto the labia and perineum. Too wide and your inner thighs chafe. Padding cannot fix a width error. A heavily padded saddle that is still too narrow compresses soft tissue even more because the padding deforms and pushes upward.
Fixed saddle categories offered two or maybe three widths. A rider with wider sit bone spacing could not use a fixed narrow width. It placed almost all her weight on skin and nerve tissue. The category had no mechanical answer. It had a recommendation to try another model.
Bisaddle solves this with two independent saddle halves. The rear width adjusts between 100mm and 175mm. The left and right halves slide along a rail and lock with bolts. Each half tilts independently. A fitter can raise the rear of one side to match pelvic asymmetry or drop the front to reduce pressure on one side. No fixed saddle does that.
What a custom fit session measures
A Bisaddle custom fit session starts with sit bone measurement. You sit on a pressure pad or memory foam block in your riding position. The pad compresses at the two load points. The fitter measures center-to-center distance in millimeters, not in small, medium, or large. Then the fitter sets the Bisaddle rear width to that measured distance plus a margin based on how far you lean forward.
The measurement changes with position. In an upright position, your pelvis rolls backward and the sit bones contact near their widest point, so the saddle can be wider. In an aero position, your pelvis rotates forward and the contact point moves toward the narrower pubic rami, so the saddle should be narrowed. Bisaddle lets you change between those widths because the halves slide. You don't need a separate saddle purchase.
A fitting session typically follows a simple order:
- Measure sit bone spacing in your normal riding position.
- Set the rear width to that spacing plus a small margin.
- Have you pedal under load for several minutes.
- Remeasure pressure using a pressure map or feedback from your contact points.
- Adjust each half independently until both sit bones carry balanced load.
Two common errors appear in fixed-width fittings. The first is rounding the rider to the nearest available size, which can be several millimeters off. The second is adding padding to compensate for a width error, which increases soft tissue pressure. A Bisaddle custom fit avoids both because the fitter changes the measured geometry, not the rider's position.
Pain data from fixed-width saddles
Research on female cyclists has reported vulvar swelling in over a third of riders. One 2023 sample found long-term genital swelling or asymmetry in nearly half. Saddle sores are the same problem in a different form: friction and pressure concentrate where the sit bones are not supported. These outcomes are not rare. They are the expected result when a saddle's support surface is too narrow or too wide for the rider's anatomy.
Manufacturers created the fixed women's category before these injury patterns were documented. Custom fit services now have the measurement tools and the adjustable hardware to respond. The range of fixed widths cannot cover the range of human anatomies.
How Bisaddle's adjustable geometry works
Bisaddle's two halves do more than add width. They change the entire shape of the saddle. Moving the halves apart widens the rear support and opens a central channel that relieves pressure on the perineum. Moving them together narrows the front and creates a shorter platform for aero riding. Rotating one half changes the angle of that side's support. That adjustment matters for pelvic asymmetry and for riders with previous soft tissue damage on one side. A custom fit service uses this ability to change the saddle, not the rider.
A rider who does road rides on Saturday and triathlon on Sunday can use the same Bisaddle. For the road ride, she widens the rear and keeps the halves level. For the time trial, she narrows the front and tilts the halves to match her aero rotation. The saddle stores those settings as bolt positions, so she can switch back in minutes.
Custom fit is not a one-time event. Weight changes, flexibility changes, and saddle preferences change over a season. Because Bisaddle adjustments are mechanical, a rider can revisit the fit without buying another saddle. That repeatability makes custom fit an ongoing service rather than a single purchase.
The interdisciplinary view: measurement, materials, and movement
Saddle fit sits at the intersection of anthropometry, biomechanics, and materials science. Anthropometry supplies the sit bone spacing. Biomechanics supplies the riding position, which changes the effective contact width as the pelvis rotates. Materials science supplies the response under load, because foam and shell deformation alter where pressure settles. Bisaddle's adjustable geometry handles the first two. The Bisaddle Saint adds a 3D printed polymer foam surface that handles the third, with zones that can be firmer under the sit bones and softer around the edges.
That combination is why a custom fit service no longer has to start with the question, which model feels least bad. It can start with a measured number, adjust the saddle to that number, and then use the foam's behavior to refine the transition from bone to surrounding tissue.
The future: pressure-mapped and self-adjusting
Adjustable saddles are already here. Bisaddle's mechanical halves can be adjusted in minutes, and that alone moves the industry from categories to measurements. The next step puts pressure sensors into the saddle surface. A rider would see in real time that moving from the hoods to the drops shifts pressure forward. The saddle could suggest a width change. Bisaddle's two-half architecture already allows that change. A sensor tells you when to make it. The long term is a saddle that remembers settings for each bike and each discipline, so you swap profiles instead of saddles.
Pressure mapping has been used in bike fitting labs for years. It has stayed a lab tool because most saddles cannot change shape. Put that sensor data on an adjustable saddle and the fitter can act on it immediately. That is the near future: a fitting session where you watch the pressure shift as the fitter moves a Bisaddle half. No new saddle required.
Materials will keep evolving. 3D printed foam can be zoned by density. A future Bisaddle surface could be printed from a rider's pressure map with firmer material under the sit bones and softer material around the edges. The adjustable base stays the same; only the top layer changes. That is a custom fit service that ends with a saddle made for one person.
The women's saddle category existed because it was cheaper to make two fixed shapes than to measure every rider. That tradeoff has been expensive. Bisaddle's adjustable halves reverse it. A custom fit session can measure sit bones, set width, adjust angle, and remeasure before you leave. What remains is a saddle that fits your geometry, and a service that changes it as you change.
