Couple days won’t matter at this point. An 11s chain should be replaced between 0.5 and 0.75! Better find a virgin to sacrifice in the lava pits of Mt. Sufferlandria so that you don’t have to replace the cassette! They are REALLY scarce out there.
Are you riding outside at all? Are you doing any efforts which put a lot of immediate power through the chain?
April 2021 I had the thought that my chain had taken a few miles and did the same park tool measurement. The chain on my Ultegra 11speed measured > 0.5% but not quite 0.75%. 2 days later (somewhat coincidence, but perhaps not…) it snapped whilst going for a Strava segment.
1 Hospital visit, 5 broken ribs, a bruised lung and don’t get out of bed for several weeks.
With 0.8 wear the chain will have worn the chainrings and cassette to the point a new chain will shift worse. The only thing to do now is run the whole drivetrain into the ground, you’ll probably get another 5000 miles, until you have to replace the lot.
Status update: DuraAce 11s chain ordered, next biz day. Just picked up a 105 cassette at my LBS, I figure the weight difference doesn’t matter on my Kickr! And I have spare chainrings if needed. Looks like I’m building a Franken-Kickr!!!
Must be that time of season. Broke my drive train on 4DP test this morning during the first 5s interval; at least it was a new PR. Something went in the chain, with an annoying “chunk” sound & thump the remainder of the test. Chain measured 1.3% elongation in one of the sections using calipers. That’s a bit more than the 0.5 to 0.8 recommendation … so new chain and cassette have been ordered. It is getting harder to find in stock 10 speed chains.
I found Ultegra 11s chains at an REI store in the Chicago suburbs. Not where I’d normally look for chains, but they do service bikes there and don’t have a high volume of cyclists coming through there. I bought my DuraAce chain at Competitive Cyclist online.
I think the X demarcates the hollow lighter chain links; I run the KMC X11SL gold on my Canyon. My original DLC chain didn’t have hollow links but my current one does.
Some reviews say KMC is only marginally better than Shimano chains but costs a lot more. Perhaps it depends on your riding conditions, so worth bearing that in mind. I get more than double the mileage out the gold 11s chain on the Canyon than I used to from a decent Ultegra chain by Shimano, and it’s not double the price here. However, I’m also a lot more pedantic about keeping my drive chain clean than I used to be. And admittedly also adore a gold chain on an otherwise 100% matt black stealth bike