1. Your Run Cramps Are a Bike Problem in Disguise

It's one of the most maddening experiences in triathlon: a debilitating cramp that derails your run, seemingly out of nowhere. You might blame pacing, nutrition, or hydration, but the real culprit is often the five hours you spent on the bike beforehand. An incorrect bike position can overload specific muscles, leaving them fatigued and primed for failure before your running shoes even hit the pavement.

Here are three common bike fit errors and the muscles they destroy:

• Saddle too low: This forces the vastus medialis—the muscle just above your knee—to do most of the work pushing the pedal down. This muscle is also critical for stabilizing the knee during the run. Overworking it on the bike is a direct recipe for it locking up on the marathon.
• Saddle too high: To compensate, riders often point their toes to reach the bottom of the pedal stroke. This constant ankle movement is managed by the calves, which end up being activated 90 times a minute. They enter T2 already deeply fatigued.
• Saddle too far back: An incorrect saddle setback can prevent proper hip rotation, causing you to bend more at the lower back. This shortens and compresses the hip flexors, leaving them tight and overloaded before the run begins.

The trade-off between aerodynamics and overall race performance is critical, and a fit that prioritizes aero at all costs can be disastrous. "An aero position that saves five minutes over 180 kilometres is of little value if the athlete is reduced to walking on the marathon. Walking for one kilometre immediately negates the time-saving."

2. That "Sit Bone" Measurement Isn't the Holy Grail

One of the most pervasive myths in saddle selection is that measuring your sit bone width is the key to finding the perfect fit. While it can be a semi-helpful starting point, for a triathlete, it's a massive oversimplification that ignores the unique demands of an aero position.

The critical flaw in this method is that it fails to account for pelvic rotation. When you lean forward into an aggressive aero position, your pelvis rotates forward, and your weight shifts from your sit bones (ischial tuberosities) to the pubic rami—a narrower section of pelvic bone further forward. A saddle must provide support for the pubic rami in this aero tuck, a nuance that a simple sit bone measurement completely misses.

Relying solely on a sit-bone measurement is like buying shoes by measuring your ankles instead of your feet—it's an assessment of a body part you aren't actually using for the specific task. Saddle choice is a complex equation where riding posture, flexibility, and riding style are just as important. For example, your posture dictates where pressure is applied: an upright position loads the sit bones, while an aggressive one loads the pubic rami. Likewise, your flexibility often influences the ideal saddle shape—less flexible riders may benefit from a rounded saddle that supports pelvic rotation, while more flexible riders can often use a flatter profile.

3. More Padding Often Creates More Pain

The most common reaction to saddle discomfort is to reach for a saddle with more padding. While intuitive, this solution is often the direct cause of more pain, not less. When a saddle is too soft, your sit bones sink into the plush padding. This might feel good for a few minutes, but it has a dangerous side effect: it transfers pressure directly to the sensitive soft tissue areas (the perineum) that aren't meant to bear weight.

This increased pressure on nerves and blood vessels is a leading cause of chafing, numbness, and saddle sores. The ideal saddle offers firm, strategic support that keeps your weight on your bone structure, not plush cushioning that allows you to sink into trouble.

4. Your Noseless Saddle is Almost Certainly in the Wrong Place

Noseless saddles, like those from ISM, are a popular solution for relieving soft tissue pressure in the aero position. However, they are also one of the most improperly installed pieces of equipment in triathlon. Because these saddles are missing the front 2-3 inches of a traditional saddle, they cannot be set up using the same reference points. If you install one based on the "nose-to-handlebar" distance of your old seat, it will be positioned too far forward and too high, leading to discomfort.

To install a noseless saddle correctly, you must follow a completely different procedure:

1. Position it further back: The front arms of the saddle must be placed about 2-3 inches (5-8 cm) further back than the nose of a traditional saddle would be. When you are riding correctly, there should be 1-3 inches of saddle visible behind you.
2. Set it slightly lower: Start by setting the saddle height 5mm (about 1/4 inch) lower than your traditional saddle. This is necessary to maintain the same effective body height relative to the pedals, as you are now sitting on a different part of the saddle's structure.
3. Adjust the tilt: A steep downward angle is not necessary. Start with the saddle perfectly level or tilted down just 1-2 degrees. The goal is to let your pelvis rotate forward naturally without causing you to slide off the front.

5. A "Good" Bike Fit Might Make You Slower (at First)

Here is one of the most counter-intuitive truths of all: it is not uncommon for your power output to decrease slightly immediately after a professional bike fit. While this might seem like a failure, it is often a powerful indicator of a successful adjustment. This temporary power "loss" happens because the new position has stopped overusing certain muscles that were compensating for a poor fit—muscles that are critical for a strong run.

For example, if your saddle was too low, your vastus medialis was likely overworked. A proper fit will engage your glutes and hamstrings more effectively, giving the vastus medialis a much-needed break. "This slight reduction in bike power is 'well and truly offset by the benefit of not being reduced to a long walk on the run.'"

6. Your Body is Adaptable, But Your Bike is Adjustable

A core philosophy in modern bike fitting is that "the bike is adjustable and the rider is adaptable." This means the bike should always be adjusted first to match your unique physiology, flexibility, and injury history. After a professional fitting, however, the second part of the equation begins. Your body must adapt to entirely new muscle loading patterns and joint angles.

This is not a quick process; sources note it can take two to three months of consistent riding to acclimate. For this reason, making drastic changes to your bike setup right before a major race is a critical error. Your body simply won't have the time to adapt efficiently, turning a potential performance gain into a race-day liability.

7. Chasing a Pro's Setup is a Recipe for Failure

It's tempting to look at a professional triathlete's sleek, aggressive setup and try to replicate it. This is almost always a mistake. Borrowing a friend's measurements or a pro's slammed stem rarely ends well because comfort is incredibly subjective. A proper bike fit depends entirely on individual factors, including your unique limb proportions, flexibility, subtle asymmetries, old injuries, riding goals, and even your power-to-weight ratio.

A professional athlete has a much higher power-to-weight ratio, meaning they have less static weight resting on the saddle. Furthermore, a pro's top priority is peak aerodynamic performance, and they are often willing to trade a significant amount of comfort for marginal gains—a trade-off that is neither necessary nor sustainable for most age-group athletes. Your bike fit must be tailored exclusively to you.