Originally Posted by
contango
If you're saving basically $4/day on gas that's $20/week or very roughly $1000/year on gas alone.
Assuming you're going to be cycling the same distance as you previously drove (and of course it may be more or less, if you can take shortcuts or if you have to take longer routes to stay off the interstate etc) you'll be doing about 100 miles per week. At that rate I'd reckon you'll be changing your chain and cassette roughly twice per year
100/miles a week is 4800 miles a year with 10 holidays and 2 weeks of vacation.
I eschewed bike computers for a decade and stopped keeping track of mileage but bought myself one 4492 miles ago last August.
I have 3740 miles on my current chain (Campagnolo C9) and can't yet measure a full 1/32" of elongation over a foot. Shifting degrades on Campagnolo chains due to side wear before they stretch to much so it'll probably get replaced with around 5000 miles on it.
When chains are rotated or replaced long enough before reaching 0.5% stretch the chain to cassette ratio can reach 4:1.
A chain a year and (all steel loose cog) cassette every four years isn't a lot of money.
My biggest wear item has been my $40/pair Bebop cleats which aren't making it through 3500 miles.