Columbus Aero Megatube

In BikeCAD, aero tubes are idealized as teardrop shapes with a circular section in the front and a triangular shape in the back. Two sides of the triangle are tangent to the circle. The chord length is simply the overall length of the teardrop and the leading edge offset is the radius of the circle. This is illustrated below.

You're right. I would normally say that a tube with such a complex cross-section should simply be mitered with a hole cut saw. However, this advice would only apply to a cylindrical head tube. I suppose this is incentive to add more cross-section options to the tubes over and above the elliptical tubing options already available.

Would be great if you could get Columbus to give you their shape files. I'm doing a bike like this soon

Is there any more news about aero profiles?

I am only asking as I am making my 3rd frame with Columbus Max tubing and the down tube is a 5 sided tear drop shape. I remember the first two I had to spend ages hand miterings them and I was hoping there was a way of making it easier on my self.

Cheers

I regret that there are no new developments on that front. My current focus is on converting the free version to a system that will not require a Java plugin.

Hi All,

i logged in to read a bitt of printing my mitering templates, i build a couple of round tubed frames that all went fine, yesterday i did a downtube on a columbus max frame and the templates are not working for me so i figured i did something wrong in printer section, from reading the above im starting to get the feeling templates dont work for shaped tubing ? i have given the tube sizes/shapes into the tube dialog box.

im about to go ahead with the top tube but then did notice that the shape printed in the dotted line is quite different from whats printed in a solid line ?

like i said i normaly use round tubinhg, i clamp these in tube blocks and run a holesaw but since i havent find away ( Yet (-: ) to clamp max tubing i have to this by hand.

what happend yesterday was disapointing but not to much of a dramma, later this year i would like to mitter a max shaped xcr tube so all info or links are more then welcome since i dont want to cut those tubes too short .

thanks, mick

Miter templates should work for elliptical tubing such as Columbus Max. For an explanation of how to define an elliptical tube, see: bikecad.ca/ovalized.

The dashed line on the mitre template represents the inner diameter of the tube, while the solid line represents the outer diameter of the tube. In places where the sides of the miter might come to a sharp point, you can expect that the profile corresponding to the inner diameter of the tube will be very different than the profile of the outer diameter of the tube. Unless you are able to vary your filing across the thickness of the tube, so that both the inner diameter and outer diameter profiles can be matched, you should file to the profile that removes the most material at any given spot.

Could you send me your BCAD file so I can investigate?

Thanks for your ( as always ) quick reply.

i realised my printer setting are of... i resently bought a windows computer, had a mac before. im running a simple cannon printer computer runs windows 10, but i cannot find the 'print actual size'button just uploaded some redicoulius driver and can now order printed tshirt from cannon but.. no actual size, ( end rant,sorry)

scale 100% is not the same as actual size is it ? i tried but it to small ?

i understand this is more an issiey in regards to my lack of understanding computers than with the software but your input is very much appriciated!

thanks again, mick

I'm sorry I can't be more help here. I would think that scale 100% would be the same as actual size. I know you should definitely leave that Automatically reduce large document that the printer cannot output box unchecked. I also know you definitely don't want Fit to page. I would be curious to know if Normal size and Scaled 100% print out differently in any way. I would not expect them to be different.