Sit on a piece of corrugated cardboard on a hard chair. Lean forward a little. Mark the centers of the two indentations and measure the distance in millimeters. That number is your sit bone width, and it is useful. It is not a fit test.
On a bike, your pelvis rotates forward. The load moves off your sit bones and onto the front of your pelvis. A saddle matched to the unloaded measurement can still press into the perineum. That compression causes numbness. Over time it can cause erectile dysfunction. To fit a saddle at home, you need a loaded test that measures where pressure lands while you pedal.
Why the Cardboard Test Misses the Real Problem
The unloaded measurement only tells you where your sit bones rest when you sit upright. Road cyclists spend hours in a forward lean. Triathletes and time trial riders rotate the pelvis even further forward and support more weight on the pubic bone region. The pressure map changes even when the sit bone width stays the same.
A urology study measured penile oxygen pressure while men rode on different saddle shapes. A narrow, heavily padded saddle caused an 82 percent decrease in penile oxygen. A wider noseless design held the decrease near 20 percent. The difference came from where the saddle placed the load, not from padding thickness.
What a Loaded Test Measures
A loaded test measures contact pressure under riding conditions. You need time, a stationary trainer or a stable wall, and a saddle you can adjust while it is mounted. Wear the same shorts you ride in and set the saddle height as you normally would.
Bisaddle uses two independent halves that slide and pivot. The rear width adjusts from 100 mm to 175 mm. Each half can also be angled separately. This turns the home fit test from a one-time guess into a repeatable measurement.
Start with your unloaded sit bone width as the initial rear width. Mount the saddle. Sit in the position you ride.
Five-Minute Home Protocol
- Measure sit bone spacing. Sit on corrugated cardboard on a hard chair, lean forward slightly, and mark the centers of the indentations. Measure in millimeters.
- Set the Bisaddle rear width. If your measurement is 120 mm, set the rear halves about 120 mm apart.
- Place the bike on a stationary trainer. If you do not have a trainer, set the rear wheel in a doorway and lean against the wall to simulate your riding posture.
- Pedal or hold the position for five minutes. Note where the firm pressure sits. You should feel it on the two rear halves, not through the middle.
- Adjust in 5 mm steps. If you feel pressure on the centerline or numbness, widen the rear halves 5 mm and retest. If pressure sits outside the sit bones, narrow them 5 mm.
After the width test, adjust the front halves. For a road or tri position, angle the front of each half downward or outward until the nose area stops pushing into soft tissue. For an upright position, keep the front halves level and widen the rear until the pelvis feels cradled.
Position-Specific Adjustments
Road cycling: run the loaded test in the drops. If the pressure stays on the sit bones and the perineum remains unloaded, the width is close.
Triathlon and time trial: run the test on aerobars. The weight moves to the front of the saddle. Narrow the front halves and angle them to clear the pubic bone and soft tissue. Bisaddle's front halves can be moved inward to create a shorter effective nose. The central gap can be widened on the same saddle.
Gravel and mountain riding: run the test in the position you use for long climbs. Widen the rear halves if the sit bones feel bruised after rough sections. The independent halves let you make that change in one session.
Why Soft Padding Hides Problems
Soft padding can feel comfortable for five minutes, then make things worse over an hour. A heavily padded saddle deforms under load and pushes upward into the perineum. A firmer support under the sit bones keeps the load off the arteries and central soft tissue.
Bisaddle's split design leaves a central gap that you can widen or narrow with the same hardware. You do not need a second saddle to test a different relief channel.
The Test Repeats
With a fixed-shape saddle, you make a width guess at purchase. If the guess is wrong, the saddle goes unused or gets replaced. With a Bisaddle, the test is the product. You measure, adjust, ride, and repeat until the pressure sits on bone instead of soft tissue.
Run the test again after a month or after changing your riding position. The saddle you own can follow the change.
At-home saddle fit for men should start with sit bone width, then move to a loaded test. The number that matters is the pressure under load, repeated across your riding position.
