www.bikecad.ca - fitting
https://www.bikecad.ca/taxonomy/term/100
enFit Advisor: Customizing Fit Formulas
https://www.bikecad.ca/customizing_fit_formulas
<div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p>For years, bicycle frame builders have used mathematical formulas to calculate appropriate bicycle geometry for a rider based on the rider's body measurements.</p>
<p>Some examples of how body measurements are taken by different builders are shown below.</p>
<img src="https://www.bikecad.ca/faqFiles/rider_measurement_styles.png" width="800" height="245" alt="Rider measurement styles" title="Rider measurement styles" class="blackborder">
<div style="clear:both;"></div>
<img src="https://www.bikecad.ca/faqFiles/squarebuilt_rider.png" width="287" height="210" alt="Rider measurement style" title="Rider measurement style" class="blackborder floright" /><p>For convenience, the three measurement diagrams above are included in <a href="https://www.bikecad.ca/bikecadpro">BikeCAD Pro</a>. However, <a href="https://www.bikecad.ca/bikecadpro">BikeCAD Pro</a> users can add their own images to the <a href="https://www.bikecad.ca/fit_advisor">Fit Advisor</a> as described <a href="https://www.bikecad.ca/customizing_fit_advisor">here</a>. An example of a customized measurement diagram is shown to the right.</p>
<div style="clear:both;"></div>
<p>If you would like to develop your own formulas for the <a href="https://www.bikecad.ca/fit_advisor">Fit Advisor</a> or modify the default formulas that are already there, start by selecting up to six body measurements to use as the basis for your fit scheme. In establishing these body measurements, be sure to reference anatomical body landmarks that will be repeatable for a variety of riders.</p>
<p>Next, find one or more riders that are already comfortable with their bike fits. By measuring these riders using our selected measurement scheme and then measuring the frame geometry of their current bikes, we'll be able to develop a fit scheme that would duplicate the fit of those riders when applied to other riders of different body dimensions.</p>
<img src="https://www.bikecad.ca/faqFiles/ridergraphic.gif" width="277" height="245" alt="Rider measurement style" title="Rider measurement style" class="blackborder floright">
<p>As an example, let's assume that we're going to use the measuring scheme on the left.</p>
<p>Let's assume that we've already measured a rider with an inseam of 32.5" and that we've also measured their saddle height and found it to be 720mm. Because this rider is very comfortable with their saddle height, we'd like to determine the ratio between the rider's saddle height and their inseam length so that we can apply that ratio to the inseam length of other riders thereby determining an appropriate saddle height for them.</p>
<p>To determine the ratio, we must first convert the 32" inseam length to millimeters. This is done by multiplying 32.5" by 25.4. The equation would be:</p><p> <em>32.5 * 25.4 = 825.5</em></p><p>The ratio of saddle height to inseam length would then be:</p><p> <em>720 / 825.5 = 0.872</em></p>
<div style="clear:both;"></div>
<p>The ratio calculated above would be entered into the <a href="https://www.bikecad.ca/customizing_fit_advisor">Fit Advisor customization screen</a> as shown below:</p>
<img src="https://www.bikecad.ca/faqFiles/saddle_height_formula.png" width="623" height="31" alt="Saddle height formula" title="Saddle height formula" class="blackborder">
<p>The above formula calculates saddle height based on a single body dimension. Saddle height could alternatively be calculated from a combination of body dimensions. Dimension <em>D</em> (the femur length in this example) might also be factored in.</p>
<p>To demonstrate how more than one body dimension could be used to calculate a single bicycle dimension, consider a formula for <a href="https://www.bikecad.ca/rider_compartment">rider compartment</a>. Because rider compartment is a measure of the distance between the saddle and the handlebars, it is reasonable to assume that this dimension should be a function of a rider's torso length and arm length.</p>
<p>Let's assume that we are still developing formulas based on the measurement diagram above. The above diagram does not have a single measurement for torso. Instead, torso length could be calculated by subtracting dimension <em>C</em> from <em>B</em>.</p>
<p>Ultimately, if we'd like to calculate a value for <a href="https://www.bikecad.ca/rider_compartment">rider compartment</a> based on equal contributions from the rider's torso length and arm length. Our formula will need to be of the form:</p>
<p> <em>x * B - x * C + x * E = rider compartment</em></p>
<p>Since <em>x</em> represents the ratio by which we'll be multiplying body dimensions <em>B</em>, <em>C</em> and <em>E</em> to obtain the recommended value for rider compartment, we can rearrange the equation to solve for <em>x</em>. The resulting equation would be:</p>
<p> <em>x = rider compartment / (B - C + E)</em></p>
<p>Again, since we already have a benchmark rider with known body dimensions and we have measured the <a href="https://www.bikecad.ca/rider_compartment">rider compartment</a> on that rider's bike, we can substitute values for <a href="https://www.bikecad.ca/rider_compartment">rider compartment</a>, as well as <em>B</em>, <em>C</em> and <em>E</em> to solve the equation. Assuming our calculated value for <em>x</em> was <em>0.52</em> the resulting <a href="https://www.bikecad.ca/fit_advisor">Fit Advisor</a> formula would be entered as shown below:</p>
<img src="https://www.bikecad.ca/faqFiles/rider_compartment_formula.png" width="657" height="32" alt="Saddle height formula" title="Saddle height formula" class="blackborder">
<p>Ideally, your final <a href="https://www.bikecad.ca/fit_advisor">Fit Advisor</a> formula would be obtained by averaging the calculated ratios from a number of benchmark riders and their respective bicycles.</p>
<p>Over time, you may feel the need to develop several more specific fit schemes. For example one fit scheme might cater to elite road racers, while another scheme might be more suitable for recreational road riders.</p>
<p>In developing BikeCAD Pro, the focus has been on creating a system where builders can apply their own fitting philosophies in an automated way. There is no expectation that builders will take the default values in the BikeCAD Pro Fit Advisor as gospel. Still, it is hoped that the default <a href="https://www.bikecad.ca/fit_advisor">Fit Advisor</a> values will yield good geometry for a wide range of riders. Therefore, if you have feedback or suggestions to improve the Fit Advisor in <a href="https://www.bikecad.ca/bikecadpro">BikeCAD Pro</a> it would be great if you could share your thoughts in the BikeCAD <a href="https://www.bikecad.ca/forum/5">Forum</a>.</div></div></div><div class="field field-name-field-tags field-type-taxonomy-term-reference field-label-hidden"><div class="field-items"><div class="field-item even"><a href="/taxonomy/term/98">Fit advisor</a></div><div class="field-item odd"><a href="/taxonomy/term/99">fit adviser</a></div><div class="field-item even"><a href="/taxonomy/term/188">formula</a></div><div class="field-item odd"><a href="/taxonomy/term/109">bicycle</a></div><div class="field-item even"><a href="/taxonomy/term/100">fitting</a></div></div></div>Sat, 22 Oct 2011 21:35:35 +0000bcurry1942 at https://www.bikecad.cahttps://www.bikecad.ca/customizing_fit_formulas#commentsFit Advisor: Applying Recommended Dimensions
https://www.bikecad.ca/fit_advisor_dims
<div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><P>
The <a href="https://www.bikecad.ca/fit_advisor">Fit advisor</a> is capable of calculating recommended values for several dimensions. A sample of some of those dimensions is shown below:
</P>
<IMG SRC="https://www.bikecad.ca/faqFiles/fitadvisordimensions.png" width="800" height="511" ALT="Fit advisor dimensions" TITLE="Fit advisor dimensions">
<p>
When applying these dimensions to the BikeCAD model, one should be careful to apply them in the correct order. Some dimensions can be applied at any time. These dimensions include
<em>crank length</em>, <em>handlebar width</em>, <em>stem length</em> and <a href="https://www.bikecad.ca/customizing_fit_advisor_2_rider_anatomy">rider anatomy</a>. Other dimensions should only be set after other dimensions have been applied. For example, the <a href="https://www.bikecad.ca/saddle_height">saddle height</a> should be set before applying the <a href="https://www.bikecad.ca/rider_compartment">rider compartment</a> or <a href="https://www.bikecad.ca/handlebar_drop">handlebar drop</a> as these two dimensions locate the handlebars relative to the saddle position.
<a href="https://www.bikecad.ca/saddle_setback">Saddle setback</a> should also only be applied after the <a href="https://www.bikecad.ca/saddle_height">saddle height</a>. Similarly, the <a href="https://www.bikecad.ca/seat_tube_length">seat tube length</a> should be set before the <a href="https://www.bikecad.ca/effective_top_tube_length">effective top tube length</a>.</p>
<p>If the fit advisor is setup to calculate values for both <a href="https://www.bikecad.ca/effective_top_tube_length">effective top tube length</a> and <a href="https://www.bikecad.ca/handlebar_drop">handlebar drop</a>, be aware that these two dimensions can each alter one another when applied. However, if you alternately apply each dimension and repeat, they will generally converge on accurate values for each dimension.
</p>
<p>
Because the <a href="http://www.bikecad.ca/rider_compartment">rider compartment</a> dimension and the <a href="http://www.bikecad.ca/effective_top_tube_length">effective top tube length</a> dimension both affect the length of the frame, it is not recommended that they be used together within a single fit scheme as one dimension will just override the other.
</P>
</div></div></div><div class="field field-name-field-tags field-type-taxonomy-term-reference field-label-hidden"><div class="field-items"><div class="field-item even"><a href="/taxonomy/term/98">Fit advisor</a></div><div class="field-item odd"><a href="/taxonomy/term/99">fit adviser</a></div><div class="field-item even"><a href="/taxonomy/term/104">dimensions</a></div><div class="field-item odd"><a href="/taxonomy/term/100">fitting</a></div></div></div>Thu, 22 Sep 2011 19:06:41 +0000bcurry859 at https://www.bikecad.cahttps://www.bikecad.ca/fit_advisor_dims#commentsFit Advisor: Customizing in BikeCAD Pro
https://www.bikecad.ca/customizing_fit_advisor
<div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p>
To customize the <em>Fit advisor</em> click on <em>View</em> >> <em>Customize</em> (or ALT-V, ALT-C). This will launch the Customization dialog box. Choose the <em>Fit advisor</em> tab shown below:
</p>
<IMG SRC="https://www.bikecad.ca/faqFiles/customize_fit_advisor1.png" width="800" height="808" ALT="Fit advisor customization" TITLE="Fit advisor customization">
<p>
The <em>Show fit formulas</em> check box determines whether or not the fit formulas will be visible in the Fit advisor.
</p>
<p>
Use the <em>Number of fit schemes</em> text field to set the number of fit schemes that you would like to define. If you change the number to a smaller value than what is currently set, BikeCAD will ignore the last few fit schemes when saving your Fit advisor settings. If you change the number
to a larger value than what is currently set, you will need to click the <em>Save settings (Fit advisor)</em> button and then close down BikeCAD. Only after launching BikeCAD again, will you have all of the fields required to define your desired number of fit schemes.
</p>
<p>
The "<em>Calculate values in increments of</em>" section determines whether or not to round the resulting calculations. For example, standard cranks are only available in increments of 2.5mm. Therefore, cranks should be displayed in increments of 2.5mm.
</p>
<p>
The rest of this dialog box is dedicated to defining the actual fit advisor formulas. The name of each fitting scheme is listed above the corresponding formulas. You needn't retain the default fitting schemes of <em>Cyclocross</em>, <em>MTB</em>, <em>Road</em> and <em>Time trial</em>. You could instead choose to fit according to other standards (Elite, sport, recreational, etc).
</p>
<p>
Each fitting scheme can have its own measurement diagram. The image file describing the measurements to be taken should be selected from the drop down menu next to the name of the scheme. The three default images are shown below. Note that while it is always recommended that BikeCAD Pro users tweak the formula in the Fit advisor to suit their own fitting philosophy, it is imperative that the formula be changed if a different measurement diagram is selected as the default formula are only intended to be applied based on the default measurement diagram.</p>
<TABLE><TR><TD><IMG SRC="https://www.bikecad.ca/faqFiles/ridergraphic.gif" width="277" height="245" class="blackborder"></TD>
<TD> </TD><TD><IMG SRC="https://www.bikecad.ca/faqFiles/ridergraphic2.gif" width="277" height="245" class="blackborder"></TD>
<TD> </TD><TD>
<IMG SRC="https://www.bikecad.ca/faqFiles/ridergraphic3.gif" width="277" height="245" class="blackborder"></TD></TR></TABLE>
<p>
If you'd like to use your own measurement diagram represented by an image file that you created yourself, you can place that image file in the directory: BikeCAD Pro\configuration\FIT_ADVISOR_IMG\ along with the other available image files shown above. The image file can be in GIF, JPG, PNG, or BMP format.
</p>
<p>
The formulas are created by multiplying some of the six basic body dimensions by various factors to calculate the output values listed on the right hand side of each row.
For example, the first line would result in the formula <strong>Crank length=0.21×C</strong>. Where <em>C</em> is <em>inseam</em>.
</p>
<p>The third line would result in the formula
<strong>Seat tube length (c-c)=0.65×C-50</strong>.
</p>
<p>There is information about formulating your own equations for the Fit Advisor <a href="https://www.bikecad.ca/customizing_fit_formulas">here</a>.</p>
<p>If you do not wish to calculate a recommended value for any given dimension, just unselect the check box on the left hand side of that row to disable the dimension. The fit advisor will not display a tab for that dimension under that particular fit scheme. If you set up formula for both <em>effective top tube length</em> and
<em>rider compartment</em>, be aware that these two dimensions will generally override one another if used in the same fit scheme. It is therefore recommended that you calculate values for <em>stem</em> and <em>effective top tube length</em>, or <em>stem</em> and <em>rider compartment</em>, but not <em>stem</em>, <em>effective top tube length</em> and <em>rider compartment</em> at once.
</p>
<p>
When saved, the Fit advisor settings are stored in the directory <strong>BikeCAD Pro\configuration</strong>. The file is called <strong>fit_advisor.xml</strong>. If you feel that your Fit advisor settings are better than the default values, I'd love to <A HREF="https://www.bikecad.ca/contact">hear from you</A>.
Through feedback from other users, the fit_advisor.xml file should evolve to produce optimal fit for the majority of riders. The most current file can be downloaded from here: <A HREF="https://www.bikecad.ca/faqFiles/fit_advisor.xml">fit_advisor.xml</A>.
</p>
<p>
The following video describes the process of customizing the Fit Advisor.
</p>
<div class="video-container"><iframe width="800" height="480" src="https://www.youtube.com/embed/39HhzEIMceo" frameborder="0" allowfullscreen></iframe></div></div></div></div><div class="field field-name-field-tags field-type-taxonomy-term-reference field-label-hidden"><div class="field-items"><div class="field-item even"><a href="/taxonomy/term/98">Fit advisor</a></div><div class="field-item odd"><a href="/taxonomy/term/99">fit adviser</a></div><div class="field-item even"><a href="/taxonomy/term/68">bikecad pro</a></div><div class="field-item odd"><a href="/taxonomy/term/100">fitting</a></div><div class="field-item even"><a href="/taxonomy/term/101">rider anatomy</a></div></div></div>Thu, 22 Sep 2011 16:34:49 +0000bcurry850 at https://www.bikecad.cahttps://www.bikecad.ca/customizing_fit_advisor#comments