Reach values are differnt on different pages

I am getting different reach numbers between the “Bike Geometry” tab and the “Bike Frame and Tubes” tab.

I can modify the number in both pages and the drive each other but I cannot figure out why my Geometry page shows 428.8 and my Frame page shows 442.

Are these different measurements I do not understand?

Stack is not the same either. I’d suggest the 428/602 is to top of spacers or underside of stem to steerer tube clamp. The head tube dimensions are different as well. Not sure where the 140 is measureing to.

Looks like the top image shows what would be “Top tube length (effective)” [607.53] and “Stack” [567.62] in Bike CAD.
607.53 and 567.62

The bottom image shows what would be the closest equivalent of “Top tube length (effective (Taiwanese))” and “Stack to top of headset” if we pretend that the effective TT length was measured to the top of the headset instead of the headtube, and that the spacer stack is part of the headset.
601.42 and 602

I don’t use rattleCAD so I’m not familiar with the different views and I don’t know what dimensioning schemes are available.

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That is what I was thinking. I think it is just a quark of the program that I did not understand. It looks like the Orange dimensions drive this document and the Red drive both. I changed stack to match the other page and now reach matches both pages. I would love to see some better documentation on the program.

For the price RatteCad is very useful. I cannot justify paying for BikeCad and this is my first bike without a full size drawing. This program seems to be accomplishing the task.


Sorry that I’m getting in so late here.

please differ between the “Bike Geometry” and the “Bike Frame & Tubes” View.

rattleCAD guides you through a process of designing a bicycle.

The separation of these views are there to simlify the process or to seperate different steps in designing a bike to fit the needs of the rider.
At first you define the position of the rider on the bike (handlebar & saddle in reference to the bottom bracket).
Before refining the tubes you define the geometry of the bike - just the geometry!
The geometry of the frame is based on this geometry.

… in other words:

In “Bike Geometry” you just determine the geometry of the bike. Any measurement of frametubes and lenghts of this tubes are there to just determine the geometry. Stack and Reach in this View are there to position the axle of the steering tube. The purple measurements in this view are optional only. They are there to see the impacts of the orange values only.

In “Bike Frame & Tubes” you have all the opportunities to refine the frame tubes. The tubes are determined here.

Manfred @ rattleCAD