Started commuting on brand new modern 9 speed roadbike back in the spring and that's how many miles I got from my first chain
. The 0.75 went in at around 1300 miles and I've been checking it once a week ever since. The 1.0 now just fits in places with a bit of pressure applied.
My old commuters had all been 7/8 speed and I'd replace the chains at 0.75 which was around 5000 miles under the same conditions. It's hard to say though as it was such along time between changes I could barely remember the previous time and the battery in the computer would likely have been relaced in that time too.
For what it's worth the 7/8/9 speed chains I'm talking about here are Shimano HG5X £10 jobbies. I've got a new KMC chain for the roadie so I'll see if that lasts longer than the HG53 that came on the bike.
I'd heard that 10 speed chains can last as little as 1000 miles on the road and I can well believe it now. If you did LEJOG on an 11 speed would you have to take a chain stretch indicator and a spare chain?
And what about 12 speed systems that seem to be on the horizon?