Wear: what's the worst that could happen?

[Paul]

I have abused my everyday bike. It's a really comfortable Freddy Grubb from the early 60s I believe. The F&F are original, everything else has been replaced over its lifetime. I got it a few years ago (maybe 10) and ran it as a fixed gear for 5 years or so before putting an old 7 speed wheel on the back.

I never clean it and the most maintenance it's had in 5 years is a squirt of oil on the chain and a wipe with a rag. It runs perfectly and almost silently. The shifting (1x7) is lovely.

Last night, for no good reason, I popped the chainchecker on it. The 1% side slipped in without making contact. I am replacing the cassette, chain, cables and chainring - they owe me nothing.

But what would happen if I didn't? I assume the shifting would get sloppy? Would the chain start to ride on top of the teeth? How far can you let components go?

[mrcharly-YHT]

AFter a load more wear, the chain would start slipping.
You might find that the chain slips now on the sprockets that you don't use very often.

[Wowbagger]

Sunderland?

[Jurek]

I did this with the first chain on my first Van Nic.
It was oiled regularly and cleaned to within an inch of its life.
The result was that it gave me ~12,000 miles of trouble-free life before developing sudden and catastrophic failure.
One morning it started to feel a bit clunky to ride, by lunchtime it wasn't rideable in any way shape or form.

[Paul H]

1X7 kept cleanish and oiled might get you further than you think, partly depends on how well distributed the wear is.  Chains skip because the wear is mismatched, on a single speed where chain and sprocket wear together you can keep going till the teeth almost disappear.  If you're predominantly in the same two or three gears, and a bit lucky, you might find it still works fine with those when the rest are skipping all over the place.
IMO, with a derailleur, you should either replace the chain before it wears the cassette, or run the lot until it misbehaves, I don't see the point of anything in between.

[Hot Flatus]

It's when the chain wheel gets worn that it gets serious. At that point if the chain starts riding on top of teeth rather than sitting in them it will unship at the worst possible moment (ie. sprinting out of saddle)  and you hit the deck.

[Paul]

It's when the chain wheel gets worn that it gets serious. At that point if the chain starts riding on top of teeth rather than sitting in them it will unship at the worst possible moment (ie. sprinting out of saddle)  and you hit the deck.

That’s one of the things I was thinking about. I think this chain ring might be quite old.
However, sprinting of any sort, but especially out of the saddle, is not happening atm.

[Hot Flatus]

Might not even need to be heavy sprinting. Could just be getting out of the saddle to pop over a short rise.

The other thing I forgot to say was that if your chain wheel is badly worn it will in turn rip through your new chain and cassette.

My routine tends to be change chain when it is worn (I use cheap SRAM chains on the commuter so it is generally rarely more than 1200 miles), chain cassette about every 6 or 7 chains (often coincides with seeing some going cheap), and then chain wheel when the teeth start to wear to sharks teeth (not always easy to spot on heavily profiled teeth like Shimano).