Bike fits don’t start with seat height, crank length or which style of aerobars is best. Fit coordinates and equipment come later. Bike fits start with making sure the rider has the proper posture on the bike. Achieving this can be anywhere from completely natural, requiring no instruction, to becoming the most challenging part of the fit.
Posture in the aerobars begins with understanding the differences in frame geometry between road and triathlon. These geometric differences largely mirror the required postural changes. The differences are twofold between road and tri frame geometry. First, the seat tube on the tri bike is steeper, bringing the saddle further forward. Second, the head tube on the tri bike is shorter, bringing the handlebars down. Taken together, these changes can be thought of as a rotation of the entire front end of the bike around the bottom bracket center. That is exactly what the rider needs to do.
The rider rotates, with the center of rotation at the hips. The rider should not slide forward, bend over, or stretch out more. Simply roll from the sit bones to the perineum. The technical term for this is anterior pelvic rotation. And there’s the rub… we aren’t supposed to sit on that! Especially the ladies. Men generally have an easier time with this, though still preferring to sit back on the sit bones if given an option. Sorry, you don’t have that option. Use the bike as it was intended to be used. (You’re allowed some help)….
Enter the modern triathlon saddle. In the early days, we used whatever was on the bike, and the phrase, “grin and bear it” was a good summary. From there we quickly moved to saddles retaining a traditional shape but with larger and more thickly padded front sections. These were an improvement, again, more for men than women. Finally, and thankfully, we entered the era of the split nosed “pronged” saddle pioneered by ISM with the original Road saddle. Bike fitters now had all the tools in the arsenal to convince both male and female riders that anterior pelvic rotation is not the end of the world. It’s the start of a proper triathlon bike fit. Until we do that, we can’t do anything else.
I leave you with this… Squeezing all the performance out of a bicycle equipped with aerobars requires more than a proper fit. It requires short and long term work on the part of the rider. You must ride it a bunch and experience some degree of touch point discomfort. You must work on relaxing and being comfortable with a lot of your weight on your aerobars (better there than on your seat!) Ceasing to use the word comfort and using instead sustainable is a good idea. Or if you must “comfortable enough” will suffice. Your triathlon bike is a single purpose speed machine, not your Laz-e-Boy. Your quest for a proper saddle should not be thought of as “Finding Mr. Right”, but rather, avoiding many possible “Mr. Wrongs”.
A talented rider, this female produced good power and had no real complaints about her position. She reported liking her typical road saddle quite a bit. My complaint about this is that she is using a road bike posture to ride a bike equipped with aerobars. No matter how ‘good’ we make this fit, we have never addressed step 1 – POSTURE.
Once we achieved proper anterior pelvic rotation, we can see how nearly every aspect of the fit changes. The back flattens and lowers, the reach to the bars is reduced and the athlete is better able to relax down into the bars. Power is the same, comfort is improved, and most importantly, the final position is a tangible improvement in aerodynamics, resulting in more speed. This is the classic definition of “free speed”.
Coach Dave Luscan is a FIST and Retul certified fitter with over 3000 fits on his resume. To find out more or book a fit, email firstname.lastname@example.org