TT/Tri Fitting Part 2:
The Pelvis/Saddle Fitting
Not all shops carry the SwitchIt so you’ll need to ask for it or find another bike shop that does. When you find a shop with a SwitchIt, try to set the position on their sizing bike or stationary bike that has it mounted it to a similar position as your triathlon bike. Try as many saddles as you like until you find the one that fits best before you make your purchase. It may come as a surprise that the seat you currently ride is not the best saddle for you. Let your tush be the judge!
Saddle Selection Misnomer
Illustration 5– tip of saddle rotated to the right. More information can be found about Cobb Saddles.
Ultimately a cutout seat may prove the most comfortable, but don’t discount those saddles without a cutout before trying them first. You may surprise yourself as to which feels best.
Illustration 6 – Heel Scrape
Illustrations 7a & 7b – Goniometer measurement and proper knee angle
Saddle Height Accuracy
Can saddle height be set to the exact millimeter? Saddle height is never the same even for the same person. What do we mean by this? What happens if they wear a different pair of cycling shorts? That precise measurement is now not so precise. Does the “millimeter measurement” account for the wear and tear of a saddle that has been ridden for a long period of time? What if the rider feels tight one day, rested the next day, or they wear additional clothing to accommodate for cold weather? The list is nearly endless. Bottom line: the millimeter adjustment is not as important as you might believe.
Saddle Fore/Aft Position
For years common thinking for saddle fore-aft positioning was determined by the knee over pedal spindle (KOPS) positioning. The KOPS fit process: place one foot forward (3 o’clock) with your crank arms parallel to the ground and then ensure that the forward knee cap is just over the center of the pedal (see picture below). For some riders, this method will work well enough for a road or mountain bike fit but that is a “maybe” at best.
Illustration 8 – Knee over Pedal Spindle alignment
Many people use a plumb bob for this measurement (we did at one time). We found a laser or the BikeFit Pro App to be easier and far more precise. While the right leg in the photo above is closest, the rider can spin the other leg forward and check the fore/aft on the far leg as well without moving the laser. We also refer to this as a “hands-free” technique. With a laser, the fitter is able to make an adjustment or simply step back and take a look. This is not possible with a weighted string hanging from the knee. Today we use this more to see if one knee is further forward than the other but NOT to check the actual saddle fore-aft position (especially on a triathlon bike fit).
Unlike road or mountain bikes, KOPS is NOT a starting point for triathlon bike fit. The modern method we subscribe to is a modified (but fairly close) Dan Empfield or Slowtwich approach. As mentioned above, my early influences come separate of Dan, having lived at the Olympic Training Center (OTC) in Colorado Springs when funny bikes were first being made. I was also influenced by working with aerodynamic guru John Cobb. We put a lot of John’s information in our first bicycle fitting manual, possibly the first fitting manual on tri bike fit. It is not that tri bike fitting was not talked about, but finding a manual for one was next to impossible.
Illustration 9 – A bike that may have been used in the 1984 Olympics – notice the small wheels
UCI Exceptions: Saddle Fore-Aft
There is an exception to the fore-aft saddle position for time trial bike fitting or for any bike that needs to be UCI legal. Because of this, it is actually easier to fit a time trial bike than it is a triathlon bike–one of the driving aspects or fit parameters is automatically set for you. We are not saying this is a good thing but rather an easier thing.
Illustration 10 – saddle set at 5cm behind the center of the BB
For USAC or UCI races or time trials, set the saddle height and put the nose of the saddle 5cm behind the BB and “Voila” you have your seat position for a time-trial bike. There are other parameters to follow. Just to make things more complicated, the UCI has a jig and your bike needs to be set up within the guideline of this jig (or template). This resembles a template for a stock car.
To see what this jig looks like, here is a bike that is set up illegally for UCI/USAC racing.
Illustration 11 – Saddle too far forward for UCI and USAC racing.
Illustration 12 – UCI bike requirements.
Additionally, not shown in this illustration are several angles and positions of the cyclist on the bike that must adhere to UCI guidelines.
Learn More About Time Trial/Triathlon Fitting
If you are interested in learning more, please see our next Time Trial/Triathlon Fitting Article: Part 3: Upper Body Positioning.