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Sliding Dropouts - 135mm spacing

Hey Brent, 


I'm using sliding dropouts (Allotec) for the first time and ran a full-size printout to help figure things out. When I measured the print to confirm there wasn't any scaling issues I noticed that the dropouts are spaced about 146 or 147mm apart not the expected 135mm (internal geared hub).

Are the dropouts represented in the aux view the "body" of the dropout and not the insert? 


135mm spacing

You can specify the rear dropout spacing in the wheels dialog box. Perhaps this dimension was overlooked and accidentally set to 146mm? There can be another source of confusion when setting rear dropout spacing. I don't think it relates to your situation, but others may find this video useful: bikecad.ca/rear_dropout_spacing_for_thru_axle_dropouts.

Hey Brent,

Hey Brent,m 


Thanks for your quick reply. Dropout spacing was my first thought but I double-checked and it seems to be set correctly. 

Could this be related to the Cz setting in dropouts? Currently it's at the default 18mm. I'm unsure how to adjust since I don't see the dropout connecting to the stay in the aux view. 


Screen shots are attached. 

Auxiliary view of sliding dropouts

This is a result of BikeCAD factoring in the thickness of the sliding inserts but not showing them in the auxiliary view. What BikeCAD is showing there is the part of the dropout that would be welded to the frame. I'm sorry it's not given in more detail, but because the auxiliary view could be shown from different angles depending on the angle of the stays, BikeCAD is not capable of guaranteeing an accurate representation of the dropouts in the auxiliary view. This is why they are shown in such a simplified form.

The C25 dropouts are shown below having been exported to FreeCAD. As you can see, the spacing between the inner faces of the inserts is 135mm. This model used 18mm for both Sz and Cz. This 18mm offset is measured from the inner faces of the inserts.

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