Good question Emily. I'm no expert, but it's definitely something that has interested me for a number of years. If you look at really old bikes (1900's) the angles (head and seat tubes) were very slack and the saddle was practically sitting on top of the top tube. Over the years there seems to be a trend to smaller frames with steeper angles - though I think the angles reached their steepest in the 80's/early 90's and have since eased off a bit. Bottom brackets have generally gotten higher as well, and chain stays have shortened. And the aforementioned steeper head angles combined with less fork rake results in a shorter front center. Add to that the shorter chainstays and you have a much shorter wheelbase. But then some British bikes from as early as the 30's (Flying Gate) have very short wheelbases, so there definitely are exceptions. Overall crank lengths have gotten a bit longer - not sure why. when I started riding in the early 70's it was hard to find anything other than a 170mm crank arm. Now 175 seems the standard in my size (57cm), though I prefer a 165. Handlebars have also gotten wider, and I know Jan Heine attributes this to better control of modern bikes with longer trail.
As for riding styles, from what little I know, to keep the proper relationship between rider and bottom bracket, as the seat angle gets steeper, you need to increase handlebar drop, which of course would favor a smaller frame. I'd love to hear some speculation on what started the trend to steeper angles/smaller frames, and why it has persisted. I personally prefer a larger bike with slack (71-72 degree) angles.
John Wood Red Lodge, MT
On Jan 30, 2008 3:12 PM, Emily O'Brien <emilyonwheels@emilysdomain.org>
wrote:
> Over the decades, as bike construction and geometry have changed, so have
> rider positions and preferences. Some things are relatively obvious how
> they affect riding styles, such as handlebars getting lower in relation to
> the saddle. Older bikes had higher bars, and the drops were in a position
> that was more comfortable for spending lots of time in, and the brake hoods
> were not as comfortable to ride on top of. As handlebars got lower, the
> drops got usable for a smaller percentage of the time, but the brake hoods
> got bigger and more designed for holding onto from above.
>
> I'm curious about other ways that riding styles or techniques have changed
> over the years. Has thinking changed about crank length? Cadence? Seat tube
> angle? How have bikes changed or changed back to favor one style of riding
> versus another? How have riding styles changed to favor one type of bike
> design versus another?
>
> I'm just curious what you all have to throw out there, be it speculation,
> hearsay, or from refutable sources.
>
> Emily O'Brien
> Medford, MA