Learn the science behind your time trial FTP and how to improve it.

Why Your TT position Slows You Down

Learn what Fabian Cancellara did, and how aero does not always equal fast.

I feel slow on my TT bike. I know that I should feel like a rocket ship, and I did when it was brand new. Now that the chainless feelings that come with a new bike have worn off, it feels slow. Fortunately, I know how to fix the problem. Unfortunately, I’ll need to buy some new parts to do so, so I’m going to keep putting it off and just avoid TTs for now. If you’re in the same boat and want to do something about it (unlike me), here’s why you feel slow and how you can fix it.

Mark Cavendish gets underway in a time trial a few years ago. He’s low, but not too long, with a mild saddle to bars drop. We’ll talk about why that matters next. Photo by Chris Peeters from Pexels

Why TT Bikes Can Make You Slower

Riding a TT bike is a balancing act between aerodynamics and power producing ability. I call it the aero-able seesaw. When positioning on a TT bike, your goal is to level out that seesaw at the lowest point possible. There’s a reason we don’t all sit on our top tubes when pedaling, more aero does not equal more able. You’re seeking the position that maximizes muscular efficiency and aerodynamics together, and that position is rarely as low as you can go.

There are many factors that go into being aerodynamic and muscularly efficient, but we’re going to focus on three, one in the able category and two in aero. For able: muscle length-tension. And for aero: saddle height and handlebar stack. These three factors are tightly related on each side of the seesaw. A small tweak to one of the aero values can make a big difference in the able value. Before we adjust, let’s break them down, starting with the aero side.

The Aero Factors

Saddle height is a concept everyone should be familiar with, so we’ll skip that and jump straight to handlebar stack. Handlebar stack is the height of your handlebars relative to your bottom bracket. On a TT bike, I like to measure to the height of the arm pads to be as accurate and repeatable as possible. Technically, that’s how we measure stack, but visually and biomechanically, we usually think about the saddle to bar drop. The photo below shows this clearly.

A Pinarello Bolide with serious saddle-bar drop, even with risers! From Glory Cycles on Flickr.

Saddle to bar drop is a combined measurement that is functionally important, and it’s what we’ll focus on getting right in the end. We first set the saddle height for maximum efficiency, then the bar height after that.

The Able Factor

On the Able side of the seesaw we have one main element, length-tension relationships. This are biomechanical element cannot be easily changed, but you can put yourself in the best position to maximize it. Here’s a quick explainer.

Muscles are made-up of two overlapping proteins, actin and myosin. To shorten and bend or extend a joint, myosin pulls on actin, like a person pulling hand over hand up a rope. This works really well when the muscle it at its optimal length. There are plenty of places for myosin to grab actin. It becomes a problem when muscles get too long or too short. An overly shortened muscle cannot develop force, since there’s little overlap between myosin and actin. Things are too bundled up. Overly lengthened muscles have the same problem, myosin can’t get a handhold, so it can’t shorten optimally. We’ve all experienced this when doing a bicep curl. It’s much harder to get the weight started than it is to continue the lift through the middle of its range. That’s due to the length-tension relationship inside the muscle.

This diagram shows what’s happening in one, microscopic portion of your muscles. Proteins have to overlap just right to contract optimally. Too short and muscles can’t go far and are weak. Too long and proteins can’t grab on and are weak as well.

Pedaling

Within a pedal stroke, three main muscle groups are activated: The glutes (especially glute max), the hamstrings, and the quadriceps. The quads extend the knee, the hamstrings and glutes extend the hip, and the hamstrings flex the knee. An ideal saddle position puts these three groups in their ideal length-tension positions to generate maximal force. In general, that position is where the leg has a 15–25 degree bend at the bottom of your pedal stroke.

Usually, TT bike saddle height is identical to road bike saddle height, so why is there a length-tension problem when you’re on a TT bike but not a road bike? That’s where the handlebar stack comes in.

Almost all of the muscles referenced above originate on your pelvis and terminate on your tibia. Your hamstrings, for example, originate from your ischial tuberosities (AKA sit bones) and insert just past your knee. That’s a long way. In normal bicycle posture, they are stretched to just about an ideal length. In TT posture, they can get pulled way too far.

Think about how you stretch your hamstrings. You straighten out your legs and bend forward. Now think about your TT position. You straighten out your legs as you’re bent forward. Spotted the problem? With a low handlebar stack, you’re putting your hamstrings in too long a position to be effective. And your glutes are experiencing the same problem!

Your quads have the opposite problem, they’re overly shortened in this position. Think about how you stretch your quads. You stand up straight, pull your knee back to your butt, and lean back gently. Exactly the opposite of your TT position! Of the four quadriceps muscles, only one attaches to the pelvis, so they’re less affected by this shortening problem, but there is still a problem. Any deviation from ideal length lessens their ability to work.

How Can You Get Faster?

To put this information to use, we need to figure out how it can make you faster. Weirdly, the answer is probably: get higher. Fabian Cancellara thought this advice was weird too. According to VeloNews, the famous fitting guru Andy Pruitt put Cancellara in a higher position in 2009, because he didn’t have adequate hamstring flexibility to pedal from down low. He won the Tour of California Prologue in January that year, but was 11th in the Tour de Romandie TT a few months later. Pruitt saw him on TV and knew something was up. Turns out, Cancellara had lowered his handlebars by 4cm (1.5 inches). Enough to strip his power away and slow him down.

If you find that your TT position is stripping away your power, try raising those handlebars up an inch or two. It will be less aero, but your power gains could make up for that, helping you find the ideal spot on the aero/able seesaw. Get that length-tension curve right and you’ll be setting new 40km PRs in no time.

Luke is a cycling coach and physiologist from Richmond, VA who rides and races bikes all over the country. He’s an expert on the body in motion and its response to exercise and loves to share his knowledge with others. Find him @LukeHollomon everywhere.