I have a few bikes with aluminum and CF forks. One of my main whips was all aluminum and I sold that bike at ~125,000 miles and had no worries about it going another 125,000. I did everything with that bike: loaded touring, mixed surfaces, commuting, rutted/rooty trails, hucking down stairs… With the much lower moment arm of the 406 and 451 wheels, I’d have absolutely zero fork concerns. FWIW, my mountain bike is full rigid with an aluminum fork, 29" wheels, 203mm front rotor (for which it’s not designed), and I beat the snot out of that bike. Still going strong with all my crashes, abuse, air time, and generally misguided actions. Between the 29er wheel and the larger rotor, that’s a looooong moment arm reefing on the fork in multiple axes.
And Terns are quite bulletproof, almost literally. I had an S27h that, among other indignities*, got caught by a loose tarp in a windstorm. Spokes broke, a pedal cracked, fenders ripped off, handlebars bent, rear rack snapped, and a huge ditch carved in the yard where it was thrashing. I repaired the damage and rode that bike another ~5000 miles. The frame and fork were just fine, just a few scratches. There weren’t even any dents. I gave that bike to a friend a five years ago, and it’s his daily driver to this day.
*It fell in the ocean a week after I bought it. Because I’m an idiot.
For folders, it really depends on your use case, budget, and fit. I’m also a huge fan of Bike Fridays, and owned four over the years: a Pocket Rocket (the 451 wheel speed demon), Speeding Tikit, and two NWT Silks. I think Tern is the better value proposition, but Fridays tend to have a better feeling ride. Bike Friday’s motto used to be “As good as your best bike.” And my Pocket Rocket absolutely went toe-to-toe with my Cannondale R2000. In some ways, the Friday was better because it was more comfortable and accelerated like a shot from a gun.
Bromptons are amazing, but just not my jam for a wide variety of reasons that probably only apply to me. :D
If you don’t really need the folding, check out mini-velos, such as the Velo Orange Neutrino.
There are other niche brands, such as Birdy or Moulton, but I don’t have direct experience with anything not listed above.
"There was a moth. I saved you from it "