Bike design

So that last post was from a scrapped blog project I started elsewhere, and since then there have been significant updates. First, my bike design: the first one here shows the relative positions of my seat and handle bars with respect to the bottom bracket. These three positions are the most important in determining the dimensions of your ride - as was told to me by the very helpful people at Cycle Sports. They are all certified by Serotta, a reputable bike builder to be sure, and this is the method they use. Once we have these specific three points in space, we can then spend days on end with BikeCAD to design the sweetest, most coolest looking bike you can dream of. The second image is the same bike design, but with it showing a different set of dimensions (BikeCAD is the shiznit).

I'll share with you some of the reasoning behind my design. It'll be a bit technical. First, I chose a bottom bracket drop of 8cm. (To spare some of you a redundancy of terminology you can check out a glossary on BikeCAD). Most production bikes have a BB drop of closer to 7cm and a lot of people like this because the bikes feel nimble. But it's actually a dirty trick on your senses. The higher center of gravity that comes with a 7cm drop, makes the bike "twitchy", but not necessarily responsive. It feels quicker, but it's actually just a classic case of conservation of momentum. The same effect is felt when you and your friend stand on a short see-saw versus a longer one. That's not a proof, just an example. Anyway, I picked a lower bottom bracket for more stability. Serotta does this, and I'm a good listener.

The top tube has a slight angle in it of 2degrees. I wanted to build it with a horizontal tt, but then I would have to make up the height elsewhere to get the handle bars where they needed to be (as determined by those three special points in the first figure). And that would reguire a large positive angled stem (which are hideous) or a lot of spacers in the headset. I went with a subtle tt angle, thus making the stem angle and spacer height also more subtle - a comprimise.