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problem: small frame

Hi, I'm making a bicycle with your software, but I think that I have a problem. While I was making a new bicycle i've notice that the size of the frame seems too small respect measures of body inserted.  I'll send you in attachment the size of the body and the size of the frame. Can you tell me if a did something wrong? do I forgot to set some option?  Or the result frame is correct? Thanks

Using the Fit Advisor with small frames

When I input your measurements into BikeCAD, I did get the same result as you.  Therefore, I wouldn't say you are doing anything wrong.  However, I will point out a few things about the Fit Advisor.

As inseam measurements get shorter, the Fit Advisor will recommend shorter and shorter cranks.  This makes sense.  However, most cranks are only available in a limited range of sizes.  Therefore, if the Fit Advisor suggests a crank length of 157.5mm, you should probably not apply that recommended length.  Instead, enter the smallest crank length that will be readily available.  In the example below, I've used a 165mm crank.

By default, the Fit Advisor will not make recommendations on stem length.  However, you can enter your own formula so that the Fit Advisor will recommend a particular stem length for a  given rider.  Some of the other dimensions you can write formula for are shown at: bikecad.ca/fit_advisor_dims.  Alternatively, you can use your own judgement about stem length prior to applying the Fit Advisor recommendations for other dimensions.  In the example below, I've used a stem length of 70mm.  I also put a greater negative angle on the stem.  The more negative angle allows for a longer head tube to be used.

Handlebar drop is highly dependent on personal preference and riding style.  It is unrealistic to expect all road cyclists of a given height to want the same amount of handlebar drop.  Therefore, the handlebar drop recommendation should not be applied blindly.  In the example below, I ignored the recommendation entirely and set the handlebar height more or less in line with the saddle.  To see where the Fit Advisor is looking to place the handlebars before applying the recommendation, use the Preview button.

My final, but most important point about the Fit Advisor, is that none of the recommended values should be taken as gospel.  There is just no way for a single set of Fit Advisor formulas to satisfy all fitting philosophies.  I encourage builders to customize the Fit Advisor formula to suit their own fitting philosophies.  There is info on customizing the Fit Advisor at: bikecad.ca/customizing_fit_advisor. For help developing your own formulas see: bikecad.ca/customizing_fit_formulas.

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