Sit bone width gets repeated more than any other number in saddle fitting. It is also the least useful. A rider can leave a fitting session with a saddle that matches her sit bone width and still feel numbness after forty minutes. The measurement was taken while she sat upright on a foam pad. The pain arrives when her pelvis tilts forward on a road bike or holds a fixed aero tuck on a triathlon bike. Those are two different shapes, and a static saddle cannot match both.
Wide, Short, and Soft: The Old Formula
For decades, saddle makers approached female fit as a subtraction problem. They started with a men's shape and made three changes: widen the rear, shorten the nose, add softer padding. The wider rear matched a wider average pelvic bone. The shorter nose avoided soft tissue pressure. The softer padding felt good in a showroom. None of those changes solved the problem in motion, because the saddle was still fixed at the point of sale. A woman who leaned forward on a road bike or rotated her pelvis on a triathlon bike had to accept the saddle's shape, even as her pain pattern changed with position.
BiSaddle replaces that fixed shape with an adjustable one. The saddle halves slide laterally from about 100 mm to 175 mm and pivot independently. The rear can stay wide for sit bone support while the front narrows to reduce thigh rub. A fitter can change the width without changing the saddle. BiSaddle describes the system as the world's only adjustable shape saddle, and the design is patented.
The Measurement Fallacy
A sit bone measurement tells you the distance between two bony landmarks while a rider sits upright on an unloaded surface. It does not tell you what those bones will do when the rider's pelvis tilts forward and the saddle compresses soft tissue. It does not account for pubic arch angle, labial geometry, perineal depth, or muscle and fat layer thickness. One survey of female riders found 35 percent had experienced vulvar swelling. A 2023 study reported nearly half with long-term genital swelling or asymmetry. Those injuries happened even though most riders had at some point been measured and fitted.
Pressure mapping can show the problem, but only once the rider is on the saddle. With a fixed-shape saddle, the mapping tells you the pressure is in the wrong place, but you cannot change the shape. You can buy another model. With BiSaddle, the mapping becomes a live tool. The fitter can widen the central gap, adjust the wing angle, or narrow the front while the rider pedals. The change is made in small increments with a hex key, not by ordering a new product.
How Adjustable Halves Support Female Anatomy
The female pelvis carries load on the ischial tuberosities in an upright position. It carries more load on the pubic rami when the rider leans into an aero bar or climbs seated with a forward tilt. Fixed-shape saddles cannot shift that support. A saddle that feels fine on a Sunday cafe ride can become a source of vulvar pain during a flat time trial. BiSaddle's two halves solve this. Each half can be angled independently, so the front can drop away or rise slightly to support the pubic bones without pressing into soft tissue. The central channel can be as wide or narrow as the rider needs, because soft tissue width and nerve pathways differ from rider to rider.
The BiSaddle Saint model adds a 3D-printed polymer foam surface on top of this adjustable base. The foam supports the sit bones with firm zones while giving way where pressure would otherwise build. That combination works differently from softer padding. Soft padding deforms under load, causing the sit bones to sink and the middle to push upward into the perineum. A soft saddle can feel comfortable for five minutes and then painful after an hour. BiSaddle uses a configurable shape first, with cushioning as the second variable. If a rider still feels midline pressure, she widens the gap rather than adding foam. That corrects the position instead of masking the symptom.
Fitting Should Be Iterative, Not a One-Time Guess
A fitting session often ends with a recommendation. The rider buys a saddle. If the first 60 minute ride shows a hotspot, the service is over. With BiSaddle, the service continues. A fitter can set a baseline width of 130 mm, ask the rider to pedal at tempo for five minutes, then widen or narrow each half in small increments until the pressure map or the rider's sensation changes. The angle of each half can be tuned independently. The front can be narrowed to create a stubby nose or split nose effect. If the rider later switches from road to gravel or triathlon, the same saddle can be reconfigured instead of replaced. BiSaddle also offers a fully noseless SRT variant for riders who want zero contact with the nose. That variant still uses the same adjustable width system.
Softer Is Not the Same as Supportive
The industry has often responded to female saddle pain by adding gel, memory foam, or a cutout. These are stopgaps. A cutout in a fixed shape may be in the wrong place for a given rider. Gel can compress and spread, reducing blood flow rather than improving it. The pudendal nerve and internal pudendal artery pass through a narrow space near the ischial spine. When a saddle compresses that area, numbness and nerve entrapment can follow. BiSaddle's design removes material from the pressure zone by widening the central gap between the two halves. If soft tissue is still compressed, the rider widens the gap further. If the sit bones need more support, she widens the rear. No amount of padding can do that.
A saddle should place the rider's weight on bony structures that can bear load, not on nerves and blood vessels that cannot. Soft padding changes how the load feels. It leaves the load in the same place. Adjustable geometry relocates the load.
A Working Fitting Protocol for Female Cyclists
- Start with a sit bone measurement as a rough starting point, not a prescription.
- Mount the BiSaddle at a neutral width, around 130 mm.
- Have the rider pedal at threshold for five to ten minutes in her usual position.
- Ask where she feels pressure: sit bones, pubic bones, or midline.
- Adjust width first, in small increments, until the sit bones feel supported and the central channel feels open.
- Adjust rear angle and front angle one at a time.
- Use pressure mapping to confirm, not override, the rider's report.
- After the session, ride for 60 minutes and then make one more small adjustment if needed. Fatigue changes posture, and the saddle should change with it.
This protocol treats fit as a continuous process, not a single measurement taken at a counter. Pain shows up after 45 minutes, after a change in saddle height, after a baby, after a shift from road to triathlon. A fixed saddle cannot keep up with any of those changes. A BiSaddle can.
The Pink Saddle Fallacy Ends With an Adjustable Shape
The pink saddle fallacy is the assumption that a female-specific design is a fixed design. That assumption fails because female anatomy varies in more ways than sit bone width. The solution is a saddle that can be adjusted while riding, after riding, and across the rider's whole cycling life. BiSaddle provides that mechanism.
