thumpism 

"Inconceivable!"

"You keep using that word. I do not think it means what you think it means."

So let's review the situation, shall we? The OP posts about a chain skipping problem. This involves a bicycle with a roller chain drivetrain composed of a crankset with a couple of chainrings, several cogs, a rear derailleur with two pulleys, the chain itself that is probably 116 links long and composed of almost 900 individual pieces, and all of this involving derailleur spring tension, derailleur hanger alignment, cable tension and lubrication to function properly, and that there is probably some element of wear. None of us but the OP has seen, heard, or touched the bicycle in question and we advisors from afar all know from our own experience that it is probably the use of a new chain on a worn cluster that is causing the problem, but you're saying that it's not a possibility for one of those many chain links to be contributing to the problem? Well, I'm glad that's settled.

Next time you go to the doctor with some ailment, don't worry when he tells you it's not a possibility that it's something you should be concerned about. I'm sure you'll live a long and happy life. It's not a possibility that anything will ever go wrong for you.

Peace out.

stevelewis

Some photos of cassette... funny how the lock ring says Chris King. I'd have thought it would say dura ace.
https://imgur.com/Osc6hnt

https://imgur.com/GVGsrcC

stevelewis

The wheelset is Dura Ace c24 if that helps. I don't have the tools or mechanical expertise to inspect freehub/pawls/ratchet.

Unfortunately it is raining so can't ride this AM and I'm out town till Wednesday so I'll have to be patient before I can test ride the bike after having cleaned the chain and adjusted the rear der tension.

Are those cassette photos detailed enough to judge how worn it is?

Shimagnolo

You can't judge a cassette wear visually, unless it is really, REALLY bad.
All the cassettes I've worn out never looked bad.
The only real test is if a new chain jumps on it, and it may jump on just one, or two cogs.

stevelewis

So I did some sleuthing by looking back at my email communications with the seller. The frame and gruppo were bought separately. The gruppo is older with "a few thousand km on it" and the frame was bought in August of this year and built up with the existing DA group. He said it was built with NEW chain/cables in August. So this all points to a worn out cassette... I just find it funny how the issue only seems to manifest in the big chainring. I did a bunch of climbing on steep hills (34tx28t) and it didn't slip. I guess the 28t and 25t cogs I used on these climbs simply weren't as worn as the other cogs further down the cogset?

monterey

could your derailer needs adjustment? You tube shows how to do this.

Shimagnolo

Smaller cogs wear faster due to load distributed across fewer teeth, and of course the cogs you use most often will wear faster than the ones you rarely use.

stevelewis

Problem persists. Though I took it to a shop and he said the cassette looks okay. He suggested we could try a new cassette or I could try doing a test where I try pedaling and then back pedaling and repeat that many times without pushing too hard to try and provoke the freehub to "fail" or not engage. I have yet to try this b/c I got home after dark and it was too cold too! Haha

If this test of quickly transitioning between coasting and pedaling reproduces the problem then I guess the pawls are not engaging? Is that an expensive fix? Can dura ace freehubs be cleaned/repaired/parts replaced? Or do I have to buy a whole new hub? :-(

Seizedpost

Did you try a new cassette? As stated above you can't tell by looking.
If coasting, then pedaling hard, reproduces the problem, it could be the freehub, or it could still be the cassette.