how fit is your fit?

Do you often wonder what can be a game changer for your Ironman race? It could be nutrition. It could be 3 flats. It could be water in our goggles during the swim.  There are more than 100 things that could go in the wrong direction that you do not have control of. 

However, have you ever thought about how your bike fit can be a game changer for your Ironman race? It’s something that can be addressed so early in the training season; it can make or break your race.  As a biomechanic physiologist, I consistently look at form, technique and position. It’s a habit I learned after grad school in the late 90’s.

During this year’s 2014 Ironman race here in Madison, I decided to take some video of riders on the first lap of the course and see how well racers were fit to their bike. ** I will be taking you through various fit points, good and bad, and how to improve on the fit, not just in regards to overall comfort, however how fit implicates performance on the bike, AND off the bike.

The following are main points regarding single measurements and how they can impact performance. Dynamic bike fitting is to be looked at as a whole when performed, however I will be taking you through specifics points here in this blog. The basic ideas below can, and should be, addressed in any fit session.

HIP ANGLE ON A TIME TRIAL/TRIATHLON BIKE SET-UP  – Bottom bracket to the greater trochanter to the AC joint (average angle to be 105-107 degrees)

Proper hip angle on a TT/Triathlon bike is hugely important for correct hip opening, power generation and muscle length/tension balance. What can this all mean?

If the hip angle is too closed down, it can produce any/all of the following:

1.       The hip is not allowed to generate enough power throughout the stroke.

2.       Climbing hills will be more difficult as the hip cannot open up enough to power over the top of the pedal stroke.

3.       With a closed angle, the hips/quadriceps/hamstring muscles cannot lengthen enough during the pedal stroke. This will in turn produce shortened/tighter muscles in the long run.

4.       A hip that cannot properly open to pedal will shut down the quads, and make the ability to run well off the bike difficult. If the frontal plane of your body (quads, abs, torso) are not long and “stretchy”, it will become increasingly difficult to run well. This can turn into back pain, hamstring overload and nausea (because the abdominals are so tight that you cannot open your torso for proper breathing and digestion).

If the hip angle is too open, it can produce some/all of the following:

1.       Over-lengthening of the muscle and myofascial tissue to cause overuse issues.

2.       Locking out of the knee joint and causing tendon issues around the joint.

3.       Nerve pulse sensations down the back of the leg.

4.       Rocking of the pelvis causing SI joint instability, thus low back pain while riding and/or running.

Checking hip angle is a confirmer in determining if the rider is sitting properly in the saddle, with respect to foot placement.


Hip angle is more then 10 degrees too low, causing a "sit back" position, low ability to carry a high cadence, and over loading the lower back area.


Once again, angle too low, and you can see a hunched upper back which will result in an overload in the quads and low back


Once again, too low of an angle.


This angle is too large. Riding in this position, will cause a more upright position to occur in the aero position. You will see this when aero bars are put on road bikes (such as you see here). Difficult to put a cyclist in a true aero position on a road bike because the geometry will not allow it. The angle you see here is great for a road position, however not very beneficial when on a road bike.

KNEE ANGLE ON A TIME TRIAL/TRIATHLON BIKE SET-UP - Angle from the greater trochanter to the axis of the knee joint to the malleolus of the ankle (proper angle 137-141 degrees).

Measuring knee angle is a great confirmer to see how well you are in position with respect to the foot to the saddle. Having a good knee angle will prevent many things such as the following.

Too short of an angle:

1.        Shortening of the quadriceps, hamstrings and calves which in turn can cause issues on the run, or a lack of power generation in the pedal stroke long-term.

2.       When the leg is not allowed to elongate properly, there is a continuous loss of power.

3.       Hip hiking can occur as you would be sitting too low on the saddle, which does now allow the leg to complete a full circle, and hip hiking can occur (loss of power, SI joint strain).

Too large of an angle:

1.        Creating elongation torque on the knee joint as you have to over-reach on the down stroke, which in turn will irritate IT bands, over stretch muscles.

2.         Hips will rock back and forth while pedaling to stay connected to the pedal, and cause laterally strain on the SI joint. This can then lead to low back pain, and strain the myofascial over that area. This will also impact run performance negatively.



Over-extension of the knee angle which will cause hip rocking and irritation of the knee and SI joint while riding and/or running.



Same issues as above. 



Just barely too small of an angle. Will feel squished and rocked backwards. This can cause lack of power while pedaling and a higher front end on an aero bike, defeating the purpose of aero. You can have a less aggressive front end, however keep the foot to butt contact points in mind.



GREAT angle! Great overall position.

PLUM LINE ON A TIME TRIAL/TRIATHLON BIKE SET-UP – Line from tibial tuberosity vertically down to foot (dynamically measured to be just in front of the shoe).

Proper plum line for a TT/Triathlon bike set-up is important. However this is in direct position to how the foot and hip are set up first. If the initial set-up of the hip angle is too low or set too far back, the plum line will not come out correctly. Once on the bike, the first check point is the foot, then move to the hip. When those two positions are in line, a plum line can be checked. The plum line should be measured from the tibial tuberosity, vertically down to the foot. For a TT/Triathlon plum, the line should drop just in front of the toe/shoe, when taken dynamically (such as when viewing video). If the dynamic plum line is too far back, the rider is reaching forward to try to generate power from the hip. Imagine going downhill skiing, and not being able to be “over” your boots on the skis for control, power and position.

If you are sitting too far behind the 8 ball, you can cause problems such as:

1.       Over-reaching of the hamstrings, which can cause numbness in the feet/low back, or “zingers” to the lower body.

2.       Toe numbness.

3.       Low back strain and tightness in the SI joint.

4.       Upper neck strain due to the over-reaching of the legs forward.

For how fast many were riding past me, I was able to snapshot a few with a view of a plum line drop.



Plum line looks good here, as well as the overall fit. Slightly crunched in the front end however, which will deactivate the abdominal core.



Pretty good plum line here! However, just by visually look this rider is most likely sitting too far back behind the bottom bracket to be the most powerful.



Plum line slightly too far back, which would tell that the cyclist is sitting a little too low and back.



Same as above, slightly too far back on the plum line, causing a total body rotation backwards on the bike, vs a forward aero position.

SHOULDER ANGLE ON A TIME TRIAL/TRIATHLON BIKE SET-UP – Elbow joint to the AC joint to the greater trochanter (average angle 85-88 degrees).

This is one of the final measurements in bike fitting for a TT/Triathlon bike set-up. This angle will be directly affected by the foot and hip positions, how the rider is sitting on the saddle, and where the arms contact the aero-pads.

Proper angles should be in the 85-88 degree range when measured from the elbow joint-AC joint-greater trochanter. If the angle is too large, some of the following can occur:

1.       Strain the muscles in the shoulder and back area, such as the serratus anterior, infraspinatus, pectoralis minor, and more.

2.       This undue strain will cause such things as neck pain, hand numbness, triceps soreness and upper back pain.

3.       Collapse of the abdominal area which will impact breathing and digestion.

Snapshots of upper body positions as triathletes rode by that day.




 This angle is a little too large. You can see the roundness of the upper body.  Fatigue will set in on the upper body, and a loss of power will occur by pushing back into the saddle.  Being relaxed over the aero bars is ideal.



Same as above, however more dramatic with an obvious slack and back position on the
bike. This will long term put pressure on the lower back, as well as the sensitive pelvic area.



Looking good, as well as plum line! Upper body looks relaxed.


Crank arm length has been the most over-looked part that I see when cyclists purchase bikes at different shops, or are fit at other places. It happens 9 out of 10 times someone comes in for a fit that I eventually complete. I have consistently seen cyclists on crank arm lengths too long, and never too short. Sometimes, rarely, they are on the correct length, and this happens by accident.  Box bikes come with crank arm lengths that are generically determined to go with bikes with no real reason except a larger crank will come with a larger bike. However, it is common to always see the crank being one to two sizes too large for the rider. Improper crank arm length leads to many issues such as:

1.       Collapse and decrease of hip motion/angles.

2.       Over-tightening the hip flexors which impede the run as well as tighten the lower back.

3.       If the circle created by the pedal stroke and crank arm length does not match the run circle made as the triathlete runs, there will eventually be mechanical failure, which will in-turn lead to decreases in performance.

4.       Irritation of lower back discs in the spine.

Crank arm length should be looked at AFTER the entire bike fit is accomplished. You can look at the overall fit and how different crank arm lengths change the pedal stroke. When on a crank arm that is too long, you will see:

1.       Hip hiking.

2.       Toe pointing at the top of the pedal stroke.

3.       Hips rocking back and forth.

4.       Low activation of the hamstrings during the pedal stroke.

5.       “Hiccup” in the pedal stroke which causes a brief loss of power, which is a lot of loss over a 112 mile course.

6.       A distinct deceleration phase of the pedal stroke that needs to be overcome each time.

7.       Decreased ability to carry the correct cadence.

Ever feel like you do single leg drills till the cows come home, however they never make it home? I will suggest to you that your crank arm is too long.

Check out a few snapshots of what the top of the pedal stroke looks like with too long of a crank arm.



Too much toeing action at the top of the pedal stroke due to too long of
a crank arm. Trying to "get over" the hump of the stroke.



Top of pedal stroke causing too high of a knee lift and having to "hiccup" over
the pedal stroke.



Showing too high of a knee lift.



Foot is almost completely vertical which will cause stress on the knee joint, hip, low back and a loss of power in the pedal stroke.

Closing thoughts...

Many things to look at; it can seem mind-boggling. However, completing a professional and dynamic bike fit will keep you fit as an athlete. Not just as a cyclist, but as a runner and a triathlete. You may think the above is all about splitting hairs, however millimeters mean a lot in the world of bike fit and performance, no matter your level of fitness/training/racing. It's time to start counting them.

As an Ironman triathlete, you spend a good 60% (if not more) of your time on the bike, with the other 40% spent on swimming, running and cross-training. This is a lot of time to create poor movement patterns that will impact your overall cycling fitness, your running form and speed, and all the way to not being able to digest food properly while racing/training.

Always remember that bike fitting is dynamic in nature, and that is changes over time. It’s a journey, not a destination to achieve.  Communication to your professional bike fitter is important in the long haul for your fitness and athletic success.