Miter Sheet Translation ?

[donevwil]

Originally Posted by spoonrobot

NHAero has the most correct stack...

I posted the same stack in post 11. Just sayin.

[spoonrobot]

Originally Posted by donevwil

I posted the same stack in post 11. Just sayin.

I edited my post to recognize your efforts. However, how did you calculate your ETT as shorter than the actual TT?

[Louis]

Next, we need to work on the geometries of these:

[Mark McM]

Originally Posted by spoonrobot

NHAero has the most correct stack, with his work shown. donevwil posted the correct stack first but didn't show his work.

I had thought the drawing was showing the headtube with estimates for headset cup thickness (20,15) but it's the actual tube dimensions given both measurements are customizable during the build process.

So the bare headtube is 139.8 which would be 581(.8) stack. My measurement was predicated on the assumption of bottom headset cup but not top headset cup (as is often done with other online geometry tools/calculators) so the "headtube" dimension I was using was 119.8 - incorrect. I have edited my initial post to highlight this error. Please excuse my hasty assumption.

Originally Posted by spoonrobot

NHAero has the most correct stack.

I had thought the drawing was showing the headtube with estimates for headset cup thickness (20,15) but it's the actual tube dimensions given both measurements are customizable during the build process.

So the bare headtube is 139.8 which would be 581(.8) stack. My measurement was predicated on the assumption of bottom headset cup but not top headset cup (as is often done with other online geometry tools/calculators) so the "headtube" dimension I was using was 119.8 - incorrect. I have edited my initial post to highlight this error. Please excuse my hasty assumption.

I understand the the reasoning above, but there must be something missing from other parts of the drawing.

Starting from the other side, the top of the ST is 532.5mm from the center of the BB, and the TT is 20.0mm below that, so the TT is 512.5mm from the BB. So the the vertical distance to the ST/TT joint is 512.5mm x sine( 73 ) = 490.1mm

The TT is 547.5mm C-C and has a slope of 5 degrees, so the vertical rise of the TT is 547.5mm x sine( 5 ) = 47.7mm.

The top of the HT extends 20mm above the TT at a 72.5 degree angle, or a vertical rise of 20.0mm x sine(72.5) = 19.1mm

So the total vertical distance up the ST to the TT, then up the TT to the HT, then to the top of the HT is 490.1mm + 47.7mm + 19.1mm = 556.9mm. Where's the other 24.9mm?

[NHAero]

Here's my guess:
Fork A-C is 396.9, plus about 15 for the lower cup, for a total of about 412mm. the vertical distance is 412 x sine 72.5 = 392.9. Subtract that from 448.5 to get 55.6 drop. That's unlikely. It looks as though the 430mm CS drops at a 9.63 degree angle to the BB, so the drop is 430 x sin 9.63 = 71.9, which seems more realistic. So I think something is off, maybe the 448.5 dimension?

[NHAero]

Here's a drawing made from importing into Bluebeam. Note that 0.1mm is 0.004". The 448.5 mm dimension measures at 448.2 mm, that is an error of 0.07% or 0.012". It's a bike frame, not a bearing race.

[Epicus07]

Thank you everyone. Those numbers are actually pretty agreeable. Very much appreciate all of your time and assistance.

[donevwil]

Originally Posted by spoonrobot

I edited my post to recognize your efforts. However, how did you calculate your ETT as shorter than the actual TT?

Doh #2, that would be because I ETT'd to the TT-ST junction, not ST extended. Corrected I get 559.6mm. I'm lazy so I used CAD.

[Epicus07]

Thank you very much for your work on estimating those fit measurements. I really struggled because it looked like it would fit perfectly but it’s been a long time since I’ve run a 14cm head tube. Even if the numbers aren’t perfect it seems well within range so i pulled the trigger. Very excited for my new bike !

[AngryScientist]

Very Nice!