Moisture

It seems like the general trend with bikes geometry has been an introduction of slightly longer top tubes (although this may have not changed much, since the effective top tube length of a sloping top tube is different from its actual length), which has consequently resulted in head tubes being somewhat taller than the seat tube. I think this is a good thing.

otherwise, we have obviously seen the introduction of newer frame materials, but I think that the way the tubing is shaped and butted would make the biggest difference here when trying to balance weight, rigidity and frame compliance.

For example, when comparing this 1980 Schwinn to a newer KHS:





You'll notice that the vintage bike has a top tube which slopes downwards slightly, while the newer designs slope a bit more upwards. What would be the most significant differences between the two design characteristics in terms of feel?

GrainBrain

Oh no dude. That paragraph ... No.

One of the biggest was Giant and their TCR in the mid nineties? Sloping top tube and compact geo.

philbob57

Over what years? When do you want to start? 1888? 1948? 2008?

Very few vintage bikes sloped down from back to front, and I doubt that the bike is the photo is one of them.

Also, note that a bike's shape is often based on the bike's purpose - criterium, Race Across America, touring, rough roads, poor roads, etc., etc., etc.

Have you tried your local public library for documentation (articles & books)?

base2 

Frame geometry has always been variable in accordance with a bikes purpose & design objectives.

If anything, road bikes are shorter in the 2020's than in previous generations, chainstays shorter than 16 inches are common. Short bikes feel faster & the faster feeling bike tends to get the sale.

But with gravel becoming popular (again,) the longer chainstays & slacker head tube angles & wider 32+mm-ish tires found on many bike-boom 1970's era road bikes (& their 1980's rigid mountain bike progeny) designed at a time when America had less paved roads are now making a come back return as current paved roads are no longer important enough to maintain. Americas return to the good ol' dirt road continues, & America (& bike design) unlikely to change course any time soon.

I think we hit peak infrastructure in about the mid-1980's when 19mm tires at 140psi was a totally reasonable & popular set up to have. You can't do that now outside of a new MUP or a velodrome, even if you wanted to...Race bikes are being designed around 25 or 28 or wider tires to compensate for poor road surface & poor infrastructure. It's no wonder the return to bike-boom geometries, tire width & pressures only with savvy gravel marketing this time around is the latest trend.

If anything, slope-ier top tubes help with the vertical compliance, so I think we'll see that trend continue for a while. What'll be different is the terms "girls bike" or "Womens specific design" will not be used. Nor will the terms "mixte" or "step through." The trend for sloped top tubes will continue though at least as long as unnecessarily stiff, low spoke count highly tensioned carbon wheels remain in fashion, especially so long as the above mentioned infrastructure erosion trend continues.

Sloped top tubes also allow for fewer frame sizes to manufacture. Less SKU's make for simpler manufacturing & more generic bike frames. All of humanity will continue to be on 1 of 5 sizes. 52, 54, 56, 58, 61 & it'll be big-bike & their shareholders that will decide this.

Internal frame dampeners (ie. Zertz) or other suspension devices such as shock absorbing seatposts, stems, or intentionally flexible thin "aero" carbon handlebars will continue their rise in popularity under the banner of "comfort." Where as in the 1970's bikes were just made with shock absorbing gas pipe & flexible singlewalled steel rims galvanized spokes.

The hoods of modern bikes are where the drops used to be. Bikes aren't designed for the drops to be the primary riding position anymore. The position of the rider hasn't changed much though.

On a related note: I feel that handlebars tend to be a bit wider than they used to be, but that may be just the bikes I've experienced.

These are just random thoughts. Feel free to "correct" my wrongthink.

Moisture

This is brilliant. Thank you for sharing.

A sloping top tube helps with standover clearance, more exposed seat post for comfort, and a more stable riding position with the longer/taller head tube. It seems to me that some angles like fork rake and head angle has been dialed down. Seems generally for the purpose of stability over loose gravel surfaces.

One thing to note, we get lots of bikes which are heavier (along with lighter) due to lower quality frame materials, cheap and heavy suspension forks/components on lower end models, etc)

Points towards an increased sense of comfort and stability over. In all honesty, i can't say that classic road bike geometry has changed all that much.

shelbyfv

Who is we? Curious to know who is getting all these bikes that are both heavier and lighter.

Koyote

oldbobcat

Since I started riding in 1970 the major change in the bikes is that I've had to size down from 59-61 cm to 57-58 cm to get a 57-ish virtual top tube. Along the way, top tubes got longer, then shorter, but never as short as before, say, 1985. Also, head tubes, got shorter, then longer, then somewhat shorter again. In 2006, when the first post-Lance Trek Madones came out, the Trek rep touted H1, H2, and H3 fits. After looking at the charts I said, very nice, but you really need an H1.5. 15 years later they finally took my advice, but only on the SLR Madones and Emondas.


In terms of position, tourists and road racers started to diverge in the late 1960s, the racers reaching longer and lower for their handlebars, and the tourists staying pretty much the same. Around 2000, with "endurance" geometry, most tourists started sitting more upright. And around 2010 the racers got lower still but with a shorter reach.


Giant introduced compact geometry in the late 1990s to facilitate fitting a broader spectrum of riders with fewer frame sizes. The idea was that the sloping top tube would make standover height less critical. Even then, they had to relent with a M/L after a couple years in order to accommodate normal 6-footers.


Handlebar shape has change too. The bends that were standard from the 1950s through the 1980s gave way to "ergonomic" bends. In my opinion they were anything but. Despite their shortcomings the traditional bars had their logic and good points, which the ergo bends tended to ignore. Fortunately, the trads never went away and the new compact bends work well for 90 percent of the riders. The main difference, though, is brake hood position, Compact bars are virtually level from the stem to the hoods, while trad bends place them a couple centimeters lower.


There is more variation in purposing bikes now, but that's mostly outside the cockpit--longer for gravel and endurance and shorter for racing. And there is more specialization now. In the old days, if you were planning on riding Paris-Roubaix or Strada Blanche, you just glued on some 26mm tubulars, double-wrapped your handlebar, and went at it. For a time trial you removed the bottle cages and put on 28-spoke wheels with silk tubulars. Even in racing now, you have aero bikes, climbing bikes, cobbled classics bikes, . . .


For what things looked like before it all got weird, I give you this image of the great Lyli Herse, a randonneur who nevertheless meant business.

Moisture

oldbobcat with manufacturing simplicity and cost cutting aside, what are some things within the industry of frame fitting you would change? Both from a performance or comfort riding perspective.