Why is bike fit so complicated? I purchased a goniometer, a plumb-bob, and a level. My wife, every time we used the goniometer she came up with the same angle. And this is only a road bike fitting! Why is this so complicated and is there a better way outside of paying $300 for a ‘fitting’?
Thanks.
if i go get a needle, a scale, and a blood pressure collar, I am still not a nurse… sorry – couldn’t resist.
I should note that my bike is a tri-geometry bike with a longer stem and road bike headset… but still the bike fitting process seems overly complicated. Wish there were a few rules of thumb for an aggressive riding position…
Wish there were a few rules of thumb for an aggressive riding position…
Um, there are…
how much were all your tools and how much time have you, and your wife spent (to date) "fitting
"…?
Not a huge amount of time. It felt like the results were fairly arbitrary and not necessarily better than I could do with just simple expirmentation or copying positions seen of good cyclists on their bikes.
HS … i was LMAO.
gd, that surprised me. thanks
HS … i was LMAO.
gd, that surprised me. thanks
Yeah, I guess that was a little abrupt. 
Here’s what I do to get a good start for fitting someone. For the initial fit, I typically follow these steps (assuming the bike is a good size fit for the individual - and that the individual does not have freakish proportions (height/inseam/torso length/etc). These are just guidelines I use (for a tri geometry bike), and do not work for everyone. For me, comfort is the key:
1: Set nose of saddle plumb with center of BB.
2: Set seat height based on a dynamic measurement of knee angle, so that the knee angle is as close to 150* as possible, but not over 150*.
3: Adjust bar height (spacers under stem) so that hip angle is approximatly 90*.
4: Adjust stem length so that shoulder (hip->shoulder->elbow) angle is less than 90* (I think 85* seems to be fairly comfortable for most I have fit).
The above seems to give a fairly comfortable position for most people I have helped. I don’t like to make static measurements - I prefer to measure dynamically, and I do so either using Dartfish or Kinovea (a free program) and a DV camera to capture video - static measuring tends to make people “pose”, and the angles tend to be off to some extent. If you would like more information on how/where I measure, feel free to ask, but I’ll be busy at a university commencement all afternoon, and not able to get to it until later - maybe someone else can post what points I, or they use to measure?
As a person gets comfortable with that position, you can get more agressive and possibly more aero by dropping the stem to some extent. Remember, for every mm you drop the stem, move the seat forward the same distance (you may need to raise the seat height some to maintain the 150* of knee angle). After making adjustments, measure angles again. Below is an image showing the angles I measure:
Why is this so complicated and is there a better way outside of paying $300 for a ‘fitting’?
In a given year I’ll ride 5 - 6 different bikes - mine plus loaners on business trips. I rarely have a problem as long as I have a 58 road bike. I set the saddle at the proper height and set-back and away I go. Takes all of two minutes or less to get rolling. Sometimes stem is a bit short, but that I can live with for a ride or two.
Not belittling the whole Fit thing as it is important, but I think some go a bit over-the-top with all this.
Fleck, you’ve got years of experience and can “feel” the right position. Most cannot.
Takizawa, the reasons for a perfected fit are generally to reduce injury and increase speed. Some people are more prone to injury than others. A poor fit can lead to injuries–more of these injuries manifest themselves on the run, actually, than on the bike. And a gifted fitter will use both objective and subjective reasoning to finding your position. So, yes, there’s more to fitting than a angle-o-meter and a plumb bob.