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Bicycle Design Software

curved downtube on 29er?

Meriwether
Framebuilder
Meriwether Cycles
By Meriwether | 1:56 PM EST, Tue January 10, 2012
BikeCAD Pro How To Forum

This is my first post and after a quick search I couldn't find how this is done. I saw someone's beach cruiser drawing so I'm sure it's possible but I see no options to add a 15 degree curve in the downtube to add long-travel suspension fork clearance (at least where I'm looking). It'd be great to have it spit out the correct miter angles so I don't have to file too much by hand!
Any help would be greatly appreciated!
Thanks,
Whit

Brent
Profile picture for user Brent
www.bikecad.ca
Ottawa, ON Canada

Brent

14 years 3 months ago

Permalink

Curved down tube on 29er

Curving the tubes of the front triangle is done in the Tubing dialog box. This is described in this video.

Below is a sample of what can be done. The location of the bend is defined as some distance A=584 between the two ends of the tube and some offset B=31 from that point. You can also specify a radius value in this case it's R=180mm. You can also display the angle of the bend and the miter angle at the end of the tube. However, these two angular dimensions are only available in BikeCAD Pro.

Curved down tube

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Meriwether
Framebuilder
Meriwether Cycles

Meriwether

14 years 3 months ago

Permalink

In reply to Curved down tube on 29er by Brent

I need to update apparently!

Thank you Brent! I am still using v6.53 so I'll update to 7 so I can get all the cool new features!

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Meriwether
Framebuilder
Meriwether Cycles

Meriwether

14 years 1 month ago

Permalink

In reply to Curved down tube on 29er by Brent

Brent,

Brent,
I'm sure you are busy and don't have to answer this, but I am wondering how you calculated the "B" value in the above screenshot (without drawing it out on paper)? I'm using the Nova DT which happens to be a 15 deg bend, but if I were to not have your help on this how would one calculate the B or R values for different angled tube bends?
thanks...

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Brent
Profile picture for user Brent
www.bikecad.ca
Ottawa, ON Canada

Brent

14 years 1 month ago

Permalink

Calculating bend angles

I could have calculated a value for B using trigonometry. However, to be honest, in the case above, I was lazy and just turned on the display of the bend angle and proceeded to type in different values for B until the bend angle hit 15 degrees. You can narrow it down pretty quickly that way. Note that the dimension B is measured to the theoretical sharp corner. Therefore, the radius value has no affect on the angle.

On another note, I trust you are now using the latest version of BikeCAD Pro which is currently Version 8.1. Because you purchased BikeCAD before the new BikeCAD.ca web site, I've manually granted your new account with the required permissions to download the new version according to the instructions here.

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