Why would it be?
The most obvious approach would be to simply scale up a q/r design until the TA will fit where the q/r skewer traditionally goes.
It might have other drawbacks, but difficult it ain't.

Why would TA cup & cone be so different from from the traditional cup & cone hubs and their limited flexibility?

Look at the exploded view here. The axle isn't like a regular threaded axle. It looks like one end is machined with the cones in place while the other end is for adjustment. The cones have to be larger as well. I suspect that the cones would also be thinner and easier to damage through mishandling.

I'm not sure what you mean by "limited flexibility".

From the exploded view, the axle for the Shimano hub is a single unit which make it proprietary. If you pit the bearings on the machined side, the whole axle has to be replaced. Given Shimano's lack of support on old equipment, I doubt you'll be able to find replacements in 3 to 5 years.

Note: Just to be clear, I don't have a problem with through axles as a mechanism. I just don't see them being all that widely used in the near future. Quick release skewers have a proven track record and they are still available on millions of bikes. They are simple and can easily replace nutted axles or vise versa. Through axles require a different frame and fork and aren't cross compatible.

This is they key for me. Millions of bikes are what make bike maintenance possible and affordable for the rest of us. I have a couple of 80s bikes, and spare parts are still readily available or painlessly upgradeable.

-1

I wanted the story to be about a guy who rode a whole century with an open QR. NO make that two open QRs.

I've never had an issue.

Most TAs have a tool-less removal feature. No more secure than 9mm QRs.

Don't confuse what Shimano has done with what can be done.
The right end still has a separately replaceable cone. Unless there is interference with the rotor mount, I can't see why the left couldn't have had that as well.

The cone would be somewhat similar in proportion to the inner bearing race of a headset than a traditional hub cone. I've never had any particular problem with those.

There's already a limit to how much a cup & cone hub can be serviced, as Shimano don't provide replacement cups.
And while cone damage is more common, cup damage does happen.
Assuming the quality of an axle with integrated cone would match the quality of a cup, there'd be no difference to the user.

Shimano seems to be about the only company outside of the very low end market that is sticking to cup and cone. I find their solution to be clunky at best and total unnecessary. Cartridge bearings offer a lot of advantages over cup and cone systems which is why so many companies have moved in that direction.

The biggest difference I see to the user is that cup and cone needs constant maintenance because it doesn't seal all that well while cartridge bearings are a use until replacement system.

You can feel the difference in the stiffness of the axle when riding over rough terrain? Which nerve endings are stimulated by this additional stiffness? :foo:

I could do it on my bike, rear dropouts are Tom Ritchey socket types, so the wheel would go nowhere, even with the QR open.

Creaks like hell if you forget to tighten it, or don't tighten it enough tho...

Unless they've changed in the past couple of years, Campagnolo still uses cup and cone for their higher-end offerings. Lower-end Campy wheels use cartridge bearings.

Chris King is still cone.

Abso-freaking-lutely.

Ask people from the MTB world. On the front end it makes a big difference holding a line in the rough, but also in corners in general.

And on a FS bike, anything that can stiffen up the rear end is welcome and noticeable when you have been riding long enough. Converting my QR rear on my OLD MKIII (which was a pretty flexy rear end) to through-bolt definitely helped under hard pedaling.

Not sure that it would be very noticeable in road applications, but I have no experience with that.

Probably I shouldn't give all the credit to just the through-axle. The fork stanchions, rim, and spokes all play their part. It's the axle interface that holds the fork legs together, and through axles and bolt-on axles provide a secure connection that aids in keeping the front end going where you point it when the going gets rough.

Chris King has a cone for adjustment purposes but they are not a "cup and cone" hub. They use a cartridge bearing.

The beauty of NO lawyer lips is that you only need to adjust your QR correctly ONCE. After that, you just flip the lever.

The stupid lawyer lips make you have to adjust every damn time you take the wheel off which is way more error prone.

:thumb:

Lawyer lips- indeed, what a pain. At a recent trade show a young sales rep demo'd me a through-axle setup, and it was even more of a pain than lawyer lips. No sale.

On my multiple road bikes I have zero evidence that there has been any movement between the hub ends and the fork dropouts.

As far as hub bearings, I walked away from a rear wheel sale last week when I found out that they had cartridges. Last thing I want is 3 years from now the cost and trouble of trying to track down some impossible to source 62091rs carts, and paying my shop $100 for the privilege of replacing them.