This article focuses on triathlon bike (TB) and time trial (TT) bike fitting. It is not intended to be a resource for bike sizing. Often these two descriptions become intertwined. However, anyone with interest in bike fitting or sizing should understand the differences. With that said, fitting a time trial bike works best when you start with the right size bicycle frame. At a minimum, a frame should be close enough to your correct size.
The position on the time trial bike we will discuss most will be the aero position–forearms sitting on the armrest with hands at the end of the aero bars/extensions. This term is referred to as “in the aero bars.” This does not render fit on the base bar or cow horn section of the bars unnecessary. On the contrary, consideration should focus here because it is the connection for starts, climbing, cornering, and where most brake levers are found. We want to help guide you to a position that you will ride almost all of the time in the aero bars. If you are not able to ride in this position comfortably, we suggest a change to the bike fit.
Triathlon or time trial vs. road bike and considerations
One thing we will not focus on in this article is whether you should be riding a triathlon bike vs. a road bike. For many, a road bike may better serve you and there is nothing wrong with riding a road bike in a triathlon. When necessary, we will specify TB (triathlon bike) or TT (time trial bike) for distinct or modality specific descriptions/reasons. Most of the time we will use “TB.” Like all cyclists, athletes who participate in triathlons, duathlons, and time trials desire comfort while riding. However, unlike many road cyclists, the triathletes and time-trialists are rarely seen sitting up and relaxing. The geometry, and thus positioning, on a time trial bike is often quite different from a road bike.
At BikeFit, we’ve developed our bike fitting curriculum to address a duathlete’s and triathlete’s specific needs. We do incorporate some of the protocols, especially with regards to hip angle, developed by Dan Empfield at SlowTwitch/F.I.S.T. This is, of course, in addition to what we perform during a typical fit (foot/pedal interface, seat height, stance width, front view, side view, etc.).
The history of “aero”
During the 1984 Olympics and around the Olympic Training Center, many people started to notice “funny bikes,: This was, of course, prior to the advent of “aero bars.” Race Across American (RAAM) then showed perhaps the first version of an “aero bar.” The RAAM guys kick-started this aero bar craze, not the triathletes as many believe. Several morphologies occurred as the triathletes attempted aero positioning. Shortly thereafter, a Boone Lennon built a set of “aero” bars for a Tour de France racer. This publicity increased the “aero bar’s” positive reception by ALL cyclists, not just the crazy long distance guys and the early triathletes. Then John Cobb helped BikeFit founder, Paul Swift, compose what may have been the first published bike fitting manual for time trial bikes and triathlon bikes in the 1990s: “The Bicycle Fitting System,” co-authored with Vint Schoenfeldt, PT.
Today, Paul Swift now also teaches at SlowTwitch, a fabulous bike fit education program run by Dan Empfield. He is a man who has taken the side view and put it into a much easier to digest format. Dan invested more time into time trial bike and tri bike fitting than anyone on the planet. It is important to note, Dan focuses on the side view perspective but also does a great job with helping fitters generate the best size frame (bike sizing) for their clients. Together SlowTwitch and BikeFit offer the most comprehensive triathlon bike fit in the world. Bike fitting that considers only the side view is like building a house and setting it on the ground without regard to the foundation. Fitting only the feet is like building the foundation but stopping before putting up the walls and roof.
The illustration above is an early version of a time trial position. This is also fairly indicative of triathlon bikes at the time that focused on the aero position. This photo shows Chris Kostman of Adventure Corps- www.adventurecorps.com. Chris is the promoter of the Furnace Creek 508 and an excellent BikeFit Pro. He certainly does not fit people like this today.
The differences between early time trial/triathlon bike fits and today
What are some of the differences with Chris’s fit and a triathlon or time trial bike fit today? Fittings at this point occurred before we started with the foot-pedal interface. Chris would point out he was at the forefront of setting the cleat further back on the shoe than most prescribed. We would argue he did it before shoes were ready for that change. With the advances in cycling shoe technology, indeed cleat position changed (foot-pedal interface information).
Two major things stand out when we look at Chris: hip angle and shoulder angle. The saddle is further back than most tri bike fits today. This results in a more acute hip angle which is exacerbated by the extra-long reach to the bar. Notice the shoulder angle; this is WELL beyond the typical 90 degrees or so we like today. Lucky for most of you, this position disappeared years ago. People ahead of you suffered so that you can achieve comfort and efficiency. A good time trial bike fit should be comfortable for the duration of your bike ride or race. You will also generate more power and increase efficiency with a quality, comfortable bike fit.
Tri (triathlon) or time trial bike position vs. road position?
From Dan Empfield www.Slowtwitch.com “The forward position places the rider over the cranks further and puts him/her in an aerodynamically sleek position. The position also saves key muscles for running. Road bike seat tube geometry is geared toward making efficient use of all leg muscles, especially the hamstrings, which is an important muscle to save for the run. Tri-geometry makes more use of the quads to generate power.”
We do believe most everyone agrees with Dan’s first statement–this forward position “places the rider…in an aerodynamically sleek position.” It is Dan’s second statement that conjures disagreement among professionals. Some studies indicated little to no noticeable change in physiological measures between a shallow seat tube angle and a steep seat tube angle. Ben Reuter and David Pascoe completed this study and published it in 2006 ‘Medicine & Science in Sports and Exercise.’ Referring back to Dan’s statement, is that the same as saying “key muscles?” You can decide. We think most professionals agree with the use of the forward (aero) position. However, all are not in agreement as to its exact benefits.
Position and comfort in triathlons
Before we get to cycling part of your triathlon (the third event), a good tri bike position should also be comfortable for someone just getting out of the water and onto the bike–this is rarely discussed. The majority focuses on transitioning to the run. While this factor is crucial, the run is far away from when you get on the bike and commence the highest speed section of your race. Let’s endeavor to place the athlete in the most comfortable aerodynamic position. In the end, what is the point of improved aerodynamics if you are unable to generate an ounce of power? We suggest when getting a triathlon bike fit, swim as close as possible or just prior to your bike fit. A few places on the planet will set this up for you. Ask if this is an interest, but places like this are few and far between.
The triathlon position tends to be more static than a road position. In other words, the cyclist spends less time adjusting or altering their body position while riding. So the main focus is, for the most part, pinpointing one position on the bike. Dialing in this single position actually becomes a bit easier than a road fit. Yet, people sometimes suggest a tri-fit is more difficult.
Sizing a tri bike is also not as complicated as suggested by some. However, sizing takes a slightly different trained eye than road bike sizing. Fitting a triathlon bike comes down to the contact points (connection points) between the cyclist and the bicycle. These NINE contact points (yes there are nine places you touch a triathlon bike): right and left pedals (1,2), the saddle (3), right and left forearms (4, 5), right and left extensions (6, 7), when in the aero position, and right and left hands (8, 9), when upright in the base bar or cow horns.
Sizing on a TB, however, probably needs to be more precise than sizing on a road bike. The choices, although many in triathlon bike accessories, can be a bit more limiting in adjustability. A proper bike fit has more to do with the saddle, handlebars, brake levers and hoods, stem and, most importantly, shoes, cleats, and pedals than the actual frame. As long as you get the equipment within the target range, you can achieve a proper and efficient bicycle fit.
Selling bicycles is the business of a bike or tri shop, and their focus is typically on the bicycle and bicycle frame. This is not necessarily a bad thing. Sometimes bias can enter the picture and hopefully, this does not negatively influence the bike fit. If the shop you choose to purchase your from is not well versed in fitting (or positioning), we strongly suggest you connect with someone with fitting expertise before your purchase. A good fitting bike may reduce more time in your triathlon than any other adjustment you make (proper training notwithstanding).
Unlike the human body, bicycles are symmetrical (other than one crank sometimes being a little wider from center than the other). That means getting the connection points into the target range is only a start to the bike fit. Not only do these points need to be in the correct area, but you need to fine tune each specific connection. Assessing and fine-tuning the location of the bike part as it meets your body is imperative. For example at the hands, just because you may have the correct length and angled stem does not mean you have the right shape and size of base-bar or elbow rest and extensions, the proper bar tilt/rotation, and/or brake levers and their location on the handlebars. Simply because you set the cleat fore/aft position does not mean its rotation, tilt, and stance width are also correct (foot adjustment). The ultimate result between the bike and your connection to it–the bicycle basically disappears. Once you no longer notice the bike and your focus exists solely on the ride, the scenery and/or company, you achieved a proficient bike fit. Similarly, while a triathlete may not care about the scenery, their concern is speed. When a triathlete no longer notices their bike, they are experiencing a great bike fit. Don’t fight with your bike! Use your motor to tear up the course. I guarantee you if your bike “disappears” during your triathlon, the transition to the run will go much more smoothly.
Getting Started with Fit (Contact Points)
As previously mentioned, the cyclist’s body contacts the bicycle at 9 points: hands (4), forearms (2), pelvis (1), and feet (2). The location of the feet, pelvis, forearms and hands dramatically impacts comfort and efficiency on the bicycle. Several pieces of equipment on a bicycle are adjusted to find your ideal position on your bike:
- Pelvis – saddle selection, height, fore/aft, tilt and sometimes cycling shorts.
- Hand and forearms – base bar, forearm pads, extensions, brake levers and shift levers (all connected to the stem).
- Feet – pedals, cleats, cycling shoes and occasionally crank arm length
Interested in expanding your knowledge? Bike retailers and shop employees with a QBP account have access to educational resources within the U of Q Training Library. Get started now.