The thing about a tech lead, is that it's not always necessary. Look at a lot of techs in the Ancient Age; Mysticism, Polytheism, Construction, Currency. If you want to wage war, you basically only need Iron Working, though Horseback Riding is nice. If you can get the GL you can get up into the Middle Ages without researching anything but early warfare techs and Literature. And even if you can't, once you've pounded an enemy into submission, you'll get a lot of those techs you missed AND a good deal of territory. And more territory means a larger economy which means more research.
I also find that if I devote the early industrial age to building railroads, hospitals and factories as fast as I possibly can, I can get a good sized tech lead (at least on Regent) and be the first to the money techs: Replaceable Parts (get this early enough, and you don't need no stinking Nationalism), Mobile Warfare and Computers.