When is it best time to replace bike chain to prevent any cassette damage?

[gbb]

On my current chain and cassette, I have done 1000 miles. I cycle regularly meaning I'd need to change both around 6 times per year.
Luckily I don't need to buy expensive components as my bike is 8 speed. Right now both chain and cassette cost together £30. £180 per year assuming Id need to change it 6 times per year every 1000 miles.
And if my bike was an 11 speed these costs would be much higher!

I am fairly new to cycling but these expenses are not very pleasant.

I would not mind replacing the chain by itself every 1000 miles.
But from all the comments I see, needing to replace both is just too expensive considering the costs.

I might need to reconsider cycling as a hobby

Even with 10 speed, I'd get 1200 to 1600 miles put of a chain. My 10 speed Veloce equipped bike is on its third chain with the same cassette and as yet shows no problems. With an 8speed, you should easily do the same if your chain is changed in good time.
Cost of an 8speed chain is what?, a tenner maybe...nothing to think about IMO, just replace the chain, it's cheap, it's a no brainer. Only worry about the cassette if you put a new chain on and have problems.

 

[Lauris]

Even with 10 speed, I'd get 1200 to 1600 miles put of a chain. My 10 speed Veloce equipped bike is on its third chain with the same cassette and as yet shows no problems. With an 8speed, you should easily do the same if your chain is changed in good time.
Cost of an 8speed chain is what?, a tenner maybe...nothing to think about IMO, just replace the chain, it's cheap, it's a no brainer. Only worry about the cassette if you put a new chain on and have problems.

Yes chain will cost around £10. I don't mind replacing it every 1000 miles or so. But both would be too expensive for me. I am buying a chain so will find out soon. On the eye cassette looks alright though

 

[Ajax Bay]

On my current chain and cassette, I have done 1000 miles. I cycle regularly meaning I'd need to change both around 6 times per year.
. . . Right now both chain and cassette cost together £30.
I would not mind replacing the chain by itself every 1000 miles.
But from all the comments I see, needing to replace both is just too expensive considering the costs.

You won't need to change your cassette and chain every 1000 miles. You don't need to change your chain now. It has not started skating, has it?
By all means change your chain, but hold onto the replaced chain. Ride out and either it'll skate or it won't. If it doesn't: happy days. If it does, put the old chain back on and ride on, till it skates. Put the new chain back in its packet. Buy a cassette in the next month. When the chain eventually skates (it will invariably only jump one half link), replace both chain and cassette. I'd expect you get 3000 miles out of a new chain and cassette combo. Personally get 5000 miles (9 speed) when I let the chain and cassette run to their joint life's end, and this is a repeated experience. Given your drivetrain is 8 speed, faffing around trying to change the chain at an arbitrary distance/percentage elongation is not worth it.
£8.50 https://www.wiggle.co.uk/sram-pc850-8-speed-chain/

 

[MontyVeda]

Will you not wear out the front rings as well then ?

of course... you can either spend the predicted £180 a year, or just replace what's worn out when it's actually worn out.

 

[Ajax Bay]

because of the geometry of the chain/chainring and chain/sprocket interfaces, and because of rotational speeds say 3 times less, chainrings wear much less than sprockets when a chain is elongated, so the cassette (and the new chain that will go with its replacement) is the limiting factor. Chainrings do of course wear, and it's the smaller ones which wear first, for the same geometric and chain/tooth interaction frequency reasons, and because the small(er) chainring(s) experience(s) higher peak forces.

Will you not wear out the front rings as well then ?

I refer the honourable member to my comment from a few days earlier, which I've taken the liberty of quoting. In the scheme of things (compared to chains and cassettes), chainring wear (and infrequent replacement) is not significant.