1. Wheel technology: Hard tires instead of pneumatic tires are absolutely horrendous, especially on any vehicle without suspension. Wheel technology of the time usually consisted of solid wood or wood spoked tire with an iron/steel rim, it is heavy as balls and you have garbage traction.
2. Gearing: You need a reliable chain and reliable gears to get reasonable speeds out of anything with a wheel under a 4 foot diameter. While such technology did exist, it was similarly heavy, required constant maintenance and lubrication, and is prone to jumping a tooth and falling off. Without being able to change gears you got a single gear ratio which makes anything but flat terrain garbage. Also like a fixy you can't stop pedaling.
3. Material science: Available materials where much shittier and far more expensive which not only made the bikes easier to damage and more prone to flexing and warping, but it also made a bike even heavier than it already was. The labor costs of making tube steel is also pretty damn high as it required skilled labor and additional tools and modern welding didn't exist to attach two pieces of pipe together without weaker flat brackets at rivets or pins.
4. Storage and hauling capabilities: Bikes, especially really heavy bikes and fixys, can't hold a whole lot, due to both space and weight limitations. Throw an extra 50 pounds on your bike and go up some of the same hills as usual and you will be whipped. People didn't just travel 20+ miles to have a cup of tea on a whim, if you are going that far or farther you are going to be bringing supplies or goods, and if you are carrying more than just a few pounds it would be easier to walk.
5. Maintenance: Without ball bearings you need to constantly oil your bearings, which also means bringing oil with you. Drive chains are not standard and have to be built, repaired, and fitted on a custom basis and thanks to substandard materials and a flexible bike it would be prone to damage. Tires require a wheelwright to build and repair custom wheels fairly often for a luxury vehicle.
5: Fitness: People of those times weren't just a bunch of lard asses so walking 20 miles isn't a daunting or, in numerous cases these days, an impossibility. People might even run most of it at the time and get a faster average speed than a fixy bike anyways. If you can't walk, you definitely aren't biking that far.
6. Terrain: While modern mountain bikers can go offroad, a fixy heavy bike with no tread/traction and hard wheels would not make it half way through a mud puddle and going down any incline offroad with one is a quick way to crashing and dieing. You would be forced to forge new paths for your bike since existing roads are mostly rutted dirt and mud over uneven ground and are also already occupying the most convenient paths.
The only places a bike in the past would be useful is a well maintained and paved stone or wooden road, however any place with flat wooden or stone roads is also going to have everything you would want within walking distance. And if you both lived in a place with such roads and also wanted to go a significant distance, there would be plenty of wagon traffic that you could simply ride on and stay relatively clean and rested rather than getting yourself covered with horse shit flying off your wheels or slipping in some horse shit and crashing your bike and ruining your extremely expensive clothes.
So basically, it is expensive as hell for an inferior product with marginal benefits in extreme edge case uses. Image having to pay $8,000 for a walmart bike, not gunna find many takers.
