I have a shimano 600 (HP-6500) headset here that has unfortunately developed an "indexing." The wheel snaps straight on the stand. This particular headset has sealed bearings.

Is it possible to replace the bearings or should I just shop around for a new headset?

Unfortunately, it's on a classic bike with a complete 600 groupset, so while I would love to replace it with a nice cheap modern headset, it just wouldn't be right.

You could look here (put up a wtb ad) for the headset you need or you could look on the bay. But I'd just buy a silver headset that would look right on the bike. You could pick up a tange levin or a velo orange headset.

I may do both of those things.

Fortunately, I found a single identical bearing at the coop. The bottom bearing had the indexing, so I replaced that with the top bearing, then replaced the top bearing with the one I found. Indexing gone...

for now...

Good to know that this will be an issue in the future though. I could always just buy a 6400 with loose balls or cages. They look almost identical.

corrado33, While I don't have an issue yet with my 6500 600 head set bearings, I think I'll research this a bit and see if there are any replacements...somewhere.

For some reason I admire Shimano for keeping the 600 script on the HS even though the name officially became Ultegra. I thought it was a carry over 'accident' back in '97 when I ordered a new Ultegra group, but the label was still the same in '99.

Brad

The 6500 headset uses regular bearings sealed inside a case. There's a silver clip that holds it together, pry the clip off with a small screw driver. The case will separate in half. Inside there are caged bearings that can be serviced or replaced.

Glad I kept the bad one then

Good that the balls can be replaced, but the "indexed" issue is usually caused by worn races, in turn caused by lack of cleaning, long use, and poor lubrication.

Don't go for a new headset. What you have is the best threaded headset ever. Replace or fix the cartridges.

The #1 killer of headsets is false brinelling. The brilliant Shimano design largely eliminates this, but is not totally immune. There is a chance that your cartridges also suffered from water intrusion, and that you may find a corroded mess on the insides. Either way, you should to take them apart and then report back.

With false brinelling, the balls dig little 'pits' into the races. This is what causes 'indexed steering'. With almost all headsets, you can eliminate the indexing by putting more ball bearings into the headset that were there before. This way, the balls now longer have the chance to line up with the pits in the races. This sounds like a kludge solution, but the headset is restored to silky smooth operation, and buys you another 5+ years of headset life.

In your case, you may as well replace all of the balls. Make sure you use the same size balls as were in there before - probably 5/32". This should only cost a couple of bucks. Crack open the carts with a small screwdriver, pull out and discard the old balls and the plastic bearing retainer, and fill up the unit with new balls. That is tight with balls, and then subtract one.

If for some reason the cartridges are really really in bad shape, trust me: try and get new cartridges. Replacing the headset with something else will involve possible stack height incompatibility, and as with any pressed-in headset install, the ever-present risk of messing up your head tube or the fork. And again: there is no 'upgrade'. Any new headset you get will be inferior to what you already have; I've owned all of them.