I think it is a great shame that the design used in my Viscount Aerospace did not become commonplace as it is maintenence free and so simple and easy to rebuild using off the shelf sealed machine bearings available from any engineering or agricultural provider for pennies.
The one development in recent years that I think might offer a worthwhile advange are disk brakes.
A weakness of the Viscount Aerospace design was apparently the groove machined into the spindle which held the retaining circlip on each side. From photos I have seen in the past this was where spindle breakages occurred. I never managed to break one, and I did an awful lot of miles on mine, but it was a known issue with the design. However, the basic principle of the design seemed good to me, and an alternative to the use of a circlip groove would not have been impossible to devise.
As for discs, like the little girl with the curl on her forehead, when they are good, they are very very good, but when they are bad, they are horrid. I have had one of each, and still have the bike with the good ones. It is one of the few developments that doesn't make life harder in other respects.
For example, drum brakes are reliable and low maintenance. They don't wear out rims and cover everything with black dust, but they add weight and make wheel removal less easy. Discs can be reliable and low maintenance, but you can't ignore them like drums as mechanical ones at least can reach a critical point where pad wear can suddenly leave you with no brake. Properly designed, they don't add weight, and they don't wear out your rims and cover everything with black dust, and wheel removal can be simpler than even with rim brakes. Also, with the above brakes, if your wheel becomes out of true, eg pothole, broken spoke, etc the brakes still work. Rim brakes are simple, easy to adjust, light, and understood by most people. They don't usually affect wheel removal but do eventually wear out rims, cover everything in black dust, and are more sensitive to wet conditions. Also, if your rim goes out of true they can be affected. But for most people they do the job well enough. All these brake types have developed their own mythology over the years.
Tin opener, can of worms. Discs can generate many threads of their own! So I'll say no more.
It's the aura of smugness that protects you.
