Can I service the bearings on one of these without removing the freewheel?

Yes, but it's so easy to remove the freewheel, you might as well just go ahead and do so. Unscrew the lockring (It's best if you have the special tool, but Channel-Lock pliers can do an acceptable job) and then just kind of lift the FW off.

Just be careful if you use a pliers: the lockring is soft aluminum and will crush easily.

I have about a dozen NOS freewheel wrenches for those hubs, if you want one, I will advertise on the For Sale forum.

To the OP - get yourself a HC wrench - they also have a bottle opener and are a valuable addition to anyone's tools :-)

Definitely easy! Easier than a "standard" FW

I wouldn't try (again) removing the lock ring without the proper tool. I mashed the only one I tried. A water pump pliers "might" work if the ring isn't too tight, but you really don't know how tight it is until you screw it up.
Besides, removing the FW doesn't gain an real advantage.

The bearings are located on the outside, so VERY easy to get to. 5/32" balls.

The more I deal with them, the more I'm intrigued by the Helico. They're an important step in the development of the geared bicycle. It was a well-thought-out system that we'd probably still be using if it had been introduced 5 years earlier.

I wonder if using a better grade of bearing to help the 5/16" balls deal with the load, and using an asymmetric rim, would help alleviate what has been commonly held as the system's weak points.

I'm not sure there is any FW that is easier than another. I just rebuilt one a couple weeks ago and the planet cages, pawls, and various parts are more difficult to assemble than an AW. For instance, if you don't get the index marks correct, the hub will not work correctly. Anyway, I'd give some thought before tearing into a FW.

I agree. They are pretty cool. I stopped by my LBS & used their tool to loosen the lock ring. Once home, I figured the freewheel could easily be pulled off, but apparently 28 years of being on there made things not so easy. I finally was able to remove it by using both hands. The freewheel pawls were gummed up, but I freed them up by drizzling in some oil once I had removed it. I didn't see any way to open it up to clean it. I can see why these were sourced on touring bikes, because with a simple flat lightweight tool you could: remove the freewheel, tighten spokes, & open your beer.

It is a shame they didn't become more popular. Fortunately mine probably has less than 100 miles on it so I should be good to go for another decade or so.

I could use one, not that I've had any issue with channel locks and a rag.

One of these days I want to slice one in half the long way on my friend's bandsaw. I'm curious to see if there's enough metal in there to cut a pocket for some standard bearing. If there is, I'm sure he can turn me up an axle easily enough.

Well there is nothing wrong with the Helico design if anything it is a mechanicaly better design than the old freewheels and is arguably as good or better than the modenr cassettete design. I was just it came out in the dwilight years for French components and cost slightly more to make which lead to its premeture demise. Some say that the slightly outward bearings on the drive side where a issue but not a problem with quiality bearings and good maintence. I road one for about ten years on a daily rider fairly hard with no problems and sold the bike and it is still going strong I see the buyer still riding it around.