Last week I had an amazing opportunity through work to forward my career and learn an immense amount of things related to cycling. I was able to attend the Trek Precision Fit class hosted at Trek Headquarters in Waterloo, WI. With so many companies out there hosting a wide variety of Fit Systems, Trek has finally jumped on board over the past year and developed one of the most state of the art systems on the market today. Jumping head first into the game, Trek has always been at the forefront of technology in the bike game, and this new system is no different. To go along with their Precision Fit bike, they have developed an in-depth, step-by-step guide to bike fitting to follow from start to finish that teaches you all the minor minutiae of each step of the process.
I won't go much in depth into the ins and outs of it here, but will point out some key subjects to keep in mind and my overall grasp of each day and as a whole.
The first day was a whirlwind of information for me. Having had very little fit experience, this was a great day for me. Going beyond just how a person should look on a bike, we spent a lot of time going over the physiology behind why a bike needs to fit each person a certain way. Generally, finding what limitations a person has so to adhere to those instead of just putting them in the most aggressive position possible.
One of the first things we talked about in great detail was the pelvis. Yea, the pelvis. Besides just how comfortable you are sitting on those narrow saddles on a road bike, the whole pelvic region is such a vital part of how you can be fit on a bike.
The simplest thing we went over first was, in layman's terms, the sit bones (ischial tuberosity). What these technically are is just the area of your pelvis that is lowest and where you end up sitting when you sit flat on a flat surface. The reason we measure these is to find out which width saddle you need to be riding on. Overall, this is just a guideline when you sit on the measurement tool. There are a handful out there, all with a gel-type substance that shows your indentations.
Without going into too much detail, what we're essentially looking for is the middle point and taking a width measurement based on those points. Many saddle companies out there have 3-4 sizes, and Bontrager (Trek) being one of them, has 3 sizes through all of their saddles (128, 138, 148mm).
The interesting thing that we learned was that there are truly very specific saddles for each riding position. It doesn't really matter what type of bike that you are riding. It has so much more to do with the actual degree of aggressiveness you have once on the bike. That being how far forward you are rotated.
What happens is as you lean forward more, your pelvis (should) rotate forward more as well. Essentially, this makes your pelvic arch become smaller and you are essentially sitting on less. Which is one reason why you see triathlon saddles so long and narrow towards the majority of the front half of the saddle.
So we also checked out a lot of other measurement tools and means of measuring.
The three main measurements that we took were: hamstring flexibility (2 ways) and hip restriction.
The two different ways to check hamstring flexibility are the standard, stand with your knees straight and stretch down as far as you can. And depending on how far you can stretch down, you are given a range of red, yellow or green. Red being not able to get below your ankles, or poor flexibility. Yellow is somewhere between your ankles and tips of fingers on the floor. Green is being able to put your hands flat on the floor.
The other way to test hamstring flexibility is to have the person being fitted lay flat on their back, grab their ankle and keep their knee straight and slowly raise it until there is some slight resistance in the leg being raised. Sometimes this is hard to tell, so if you watch their opposite leg, you can see their foot move or pelvis start to raise once you hit this point. What this tells us is how much the rider can activate their hamstring while their leg is extended at the bottom of the pedal stroke. Giving us a better idea of how high their saddle should be.
The final test I will cover in this post regards your hip restriction. The reason I find this test so great is that it really can tell your rider and you how they need to be saddled up on the bike.
So after testing the hamstring on the second test I mentioned, keep your rider on the ground or table where they are laying, pull up under their knee and drive it upwards towards their chest until you have heavy resistance. What your doing is finding out how high the rider can drive their knee through at the top of the pedal stroke and still have it be usable power at this point. You need to take a measurement at this point using a goniometer.
What I really like about this test (not what is pictured above, that is just to show a goniometer) is that it can really give the rider a better idea about crank arm lengths. Something of a dirty subject in the cycling world from time to time. Some school of thought (old school) is that the bigger the better. Longer crank arms, more torque, more power. But what has happened is that tests have been done to prove that whether you ride a 150mm or 200mm crank arm, the same amount of power can be produced without any loss in performance. So testing a rider's hip restriction can help them get on a better sized set of cranks for better performance. It doesn't matter if you're 6'5" or 5'6", you could both need 165mm crank arms.
If you want to think about it another way though, especially for those fitting triathletes, using shorter crank arms makes the athlete 'spinnier' or it's easier to move through the pedal stroke faster. For triathletes, this is great since it uses less of our big muscle energy, saving energy for the run. And for pure cyclists, it can lessen the stress load on joints. Climbers tend to want a longer crank so they can torque through as well as sprinters, but beyond those specialists, cranks should be fit based on what I noted above, not so much on height.
That's it for this one, stay put for Trek Precision Fit Day 2.
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