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Simple question about tube measuring for cutting

Hi I tried to find the answer using the forum search. I would like to confirm that the length of tubing to be cut before mitering using the templates are the ff: I might be a silly question but just want to confirm. Thanks! this is only possible for constant diameter round tubing and does not apply to Columbus Max...?

Thanks again!


frame diagram

Length of tube to cut

Your diagram shows a center to center top tube length of 525mm and a center to center down tube length of 616mm.  Informing the builder of what length to cut the top tube and down tube before mitering is not necessarily the primary purpose of these dimensions.  However, it would be quite acceptable to use them for that purpose.

If the diameter of your seat tube, top tube and head tube were all the same, then the center to center top tube dimension would actually represent the exact length of your top tube after mitering.  However, in most situations the center to center dimension is going to give you a slightly longer length than you actually need.  Notice in your example because the head tube is a larger diameter than the top tube and down tube, neither the top tube nor the down tube extend all the way to the center of the head tube.

If you are looking to minimize scrap by cutting your tubes before mitering to the exact finished length, you'll need to create a user dimension to show that length.  An example of such a dimension is shown below:

It is not necessary to create such a dimension for the seat tube as this value is already available in the Mitring tab of the Dimensions dialog box.  This dimension is shown below:

Once your tubes are rough cut, the critical dimensions you'll need to locate your miters are the miter to miter lengths described at: bikecad.ca/miter_to_miter.  Miter to miter lengths will be accurate regardless of the tube cross sections involved.

Using the center to center measurements to pre-cut your tubes is also a good conservative approach for tubes of unusual cross sections.


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