Originally Posted by himespau

I know this sounds a bit odd, but hear me out.

After I got hit last year (took me 5-6 months to recover and I'm not still 100% there), I have done almost all my riding indoors (like 7800 out of 8000 km as a rough estimate to give you an idea). Because I have cats who are very jealous and rub up against my bike whenever they seeing me getting my kit on, I've switched to using hot wax to lubricate my chains rather than the oil-based lubes I used to use (not trying to start a chain lube thread), so that my wife doesn't get upset because of cats with oily fur tracking it through the house. I have 3 chains that I rotate between every 500-1000 km.

I've recently started working on building up a 2nd bike so that I don't have to take one off the trainer and put wheels on it and stuff when I want to ride outdoors. The new (to me - it's a ~26 year-old Merckx) is Ti, so it's probably going to be my indoor rider to save my beautiful steel Colnago from more corrosive sweat exposure (I do wipe it down after every ride, but indoors means lots of sweat and maybe not the best evaporation, so I worry). Because I was planning on doing the Merckx Ti indoors, I stripped and pre-waxed 3 more chains for it. The plan was to keep the 3 waxed chain rotation for my Colnago when I ride it outside as well in case I decide to ride it inside later.

After fitting and cutting the first of the waxed chains for the Merckx today, out of random curiosity, I took it over and held it up next to one of the chains for the Colnago that was waiting for another trip through the wax bath. I was a bit surprised to see it was the same length (maybe I shouldn't have been, both are road race bikes from the same era, so similar geometries and both have 10 speed triples with medium cage Centaur rear derailleurs - the only difference is the chainrings on the Merckx are 2 teeth bigger on each ring).

I then got to thinking, if the chains are all the same length (and I held the new chain for the Merckx next to chain that's in the rotation for the Colnago and didn't see any significant length difference - I didn't lay them out and specifically measure), is there any reason I can't just put the 3 chains that I've got for each bike into one common pool and rotate through all 6 of them every time I need to change? The one thing I can see is that the Colnago chains each have ~2500 km on them, and going forward, if it's outside the Colnago won't get as much use, so all the chains would spend more time on the Merckx and over time would stretch to match that cassette.

Since they require the same length, can I keep them together, or is it in the best interest of both of my drive trains to keep track of which chains go with which bike and hang them separately in my parts closet?