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  1. #1
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    Help with BikeCad?

    Hello Everybody,
    I am new to this whole forum thing. I was wondering if any of you would be willing to help me with figuring out my frame conundrum.
    I recently had my Fat Chance Wicked stolen so my first question is does anybody have the geometry specs for these, I bought it new in 87.
    The reason I ask is that I want to build my first frame like the Wicked but set up for 650b.
    I have made some drawings but before I hack up some tubing I want be sure on the dimensions, would any of you with experience be willing to help me sort out the details here maybe run some numbers through some sort of program? I want to make this frame and possibly one more set up for drop bars. Any help or advice would be greatly appreciated! I have many years welding fabricating experience (not to mention a shop) so I am very confident this is within my abilities.
    Thanks for your time, Matt
    Last edited by Forged1; 12-16-2011 at 08:58 AM. Reason: Did I put this in the wrong place?

  2. #2
    dru
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    If you are going to use the free version of BikeCad you need to remember some basic high school trig in order to calculate all the angles and tube lengths you'll need. I'm far from being a pro at design or building but I do have two frames under my belt using BikeCad. The first frame was practice thank god, because I made some math errors.

    The second frame turned out perfectly, and I ride the bike every week. Design was easy for me with my 26er since the general angles and lengths are widely accepted and have been for many years. I wanted middle of the road quickness and that's exactly what I got.




    You can't really expect to do more than approximate handling when going from one wheel size to another, especially coming from such an old ride. Way too many variables in play. You'll need to find out what the 650 crowd is running for geometry #s and go from there. They aren't that common or that old so the info might be scarce.

    You'll need to tweak the #s to suit what you want handling wise. When you are done that you need to pick out tubing diameters as well as figuring out what fork you are running, its offset, and any sag before trying to run off a drawing from BikeCad.

    Anyways, as you've found by viewing or printing your drawing the program doesn't give you all the angles you need.

    You need to use the sine law and cosine law to get the rest of your numbers from the info provided.

    It is not hard, it should take no more than an hour using a scientific calculator or sine and cosine tables.

    sine law: A/sin a = B/sin b = C/sin c

    cosine law: a2 = b2 + c2 - 2bc cos C

    Drew
    occasional cyclist

  3. #3
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    Thanks Drew, I have been freshening up on my trig lately. Are you using Bikecad pro?
    -Matt

  4. #4
    dru
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    No I'm not, just the free version. Some of the pros use it, but then they can justify the expense. For a guy who's building just a frame or two the free version makes more sense. They obviously don't make it easy though since they'd like to sell you the pro version instead. That is why you need the trig, and a mitre program too, I might add. Once you mucked around a bit with the math you can actually design frames on paper fairly easily, although some of the dimensions that BikeCad offers are really useful and important even for the free version.

    Oh, the guys on the frame forum really will run you through the grinder btw. I think they get so many posts from people who aren't serious, lazy, or out right dumb that it gets under their skin. Peter (PVD) can be particularly abrasive, but is a really smart guy. Be humble over there and think twice before you post.

    Drew
    occasional cyclist

  5. #5
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    Hey Thanks again Drew. You are wise. "Abrasive" I've been called that among other things as well. Take it easy.
    -Matt

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