Wednesday, September 20, 2023

A Search For "Gravel" Geometry": Part 2 - Myths & Traditions

Delving into the world of geometry for any bicycle is a lesson in how various opinions are held in high regard, how traditions affect reality, and how reality is often nothing like what anyone thinks it is. 

Okay, so do the science. Check out the data! That should square things up, right? Right? Well, considering that humans ride bicycles, and not robots, you have one gigantic, monstrous wildcard in the equation. Consider this quote I came across in my research from an article on page speaking about a research paper done by a couple of scientists that was being discussed there concerning geometry and bicycles:

 "However, they do stress the extremely important point that the person-machine relationship is so complex and so variable that mathematical models and absolute statements are, at very best, only a rough guide."

"Only a rough guide"? Yep! do we know anything for certain then? Great question. It just is hard to get through the cloudy, vagueness introduced by us humans. Consider confirmation bias, beliefs in personalities, hearsay, and myths passed down as "truth". Most of which are things based on theories that haven't been thoroughly vetted or are not considering this "human factor" at all. 

Speaking of which, I ran a fork test in 2008 where I tried to keep everything the same except the fork. I accounted for handlebar positioning, bottom bracket height, saddle to handle bar height, and more. I ran suspension forks and rigid forks. 

I tried this 430 A/C, 38mm offset fork and 7 others on the same 29"er.

The main thing I learned there was that the human element is a powerful one. I learned that within a few rides I was able to make almost every fork work the way I wanted them to. Differences? Yes, there were, but adaption? Yes. Totally. 

And every set up has to be seen as a system, which is something I've held to be very important for years. One measurement, one change, affects everything. You cannot point at "head angle" or whatever, and say "that's going to be "this" in terms of handling. 

Then there seems to be some widely held "truths" about geometry that may have been originally thought out not because the old designers were seeking a handling trait, per se', but as a way around a materials limitation. Take, for instance, the popular "low trail" (trail figure is a measure of front end geometry) designs popularized by old French "constructuer" builders. A site I discovered during my research claims that back in the day, drop bar handlebars had a longer reach. This was due to limitations in manipulating the handlebar stock, which forced these bars to have a long reach, which in turn affected overall reach for a rider. So designers had to shorten the top tubes accordingly. This led to massive toe overlap, so the answer was, according to this source, low trail geometry. Low trail geometry features a longer fork offset which pushes the front wheel out front, further away from the rider.

Now that source's claims can be debated. But the argument put forth there is plausible, and it illustrates how a solution to a problem becomes religion after decades of use and lore are layered on top. Now the common ability to bend and shape materials helps illustrate why things like longer top tubes, shorty stems, and slacker head tube angles are becoming more popular now. This stuff isn't "new" though. In fact, it was figured out a century ago. It's just that it took a revolution in thinking about geometry, instead of just sticking to the ordinary ways, which were partially driven by traditions, but also by ease of manufacturing concerns. 

The staid old ways of thinking were entrenched in the industry for decades, until mountain bikes came along, that is, and in particular, the 29" wheel, which kind of blew the doors open on design which had been closed for so long. (Read about the story of where 29"ers came from HERE)  Old ways were rediscovered that had been forgotten, and traditional thinking and ease of manufacturing had less of a hold on bicycle design. Now is "The Golden Age" of cycling. You've had choices brought forth in the last 20+ years that were unheard of before 2010 and are now commonplace. 

Next: New freedom to dream up a "new" kind of bike. But is it really new?

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