I have one of those park tool chain checkers but is there a similar thing for the chainrings and chainsets?

The reason for asking is that the chain is on the .75 now and i will change it but the chainrings and cassette are quite old so should i be chainging them too? Gear changes seem to be ok at the moment but what will it be like when i put a new chain on?

Any tips or pointers would be great. Ta

Working at a bike shop, we wouldn't reccomend you changed the chain until it is closer to 1% stretched. The manufacturers go along these lines too, and if you change the chain on or before this point the chainrings & cassette it has ran on will run sweet with a new chain – so I'd etch more life out of that chain!

To answer the question though, there isn't a tool for the rings that I'm aware of, you get to learn the look of wear, but if that chain you measured at 0.75 was on them for new I would keep them on – if you get chain such or it slips under power change them by all means. Hope this essay helps!

thanks for the help swalsey although i'm a little confused by your first bit. surely if the chain is stretched more then the chainrings and cassette will be more stretched too? Or is that wrong?

And i think this is the second chain on these rings/cassette.

No problem – I'll continue!

If the chain has stretched running on the rings, the chain and cassette will have worn, but it's only a problem when the chain has worn beyond 1% and the gap between contact points on the rings becomes too large for a no-worn chain to run.

Say if you run a chain to 2% stretch on the rings (which will also have worn to match), them put a new chain on at 0.5% stretch – the distance between pins on the new chain will be shorter than the worn contact points on the old rings, so it won't run properly. By replacing the chain more frequently you maximise the life of the rings & cassette – you can easily get multiple chains worn out before the cassette and rings need replacing. I'd aim for three per cassette, although if you tend to use certain rings more than others (i.e. granny ring) you may find they need replacing sooner.

If that not clear, don't think about it and aim to replace cassette and rings after 3 worn chains. Feel free to ask if I can be of more help, but don't waste your hard earned until closer to 1% 🙂

from experience rather than science:

I change chains at between 0.75 and 1% stretch, and can usually get through 3 chains before the cassettes go. I haven't got a tried and trusted method, but I make sure that the next cassette and middle chainring are in the parts box in preparation. On the basis you'll need them eventually I then see if the third chain will work OK with the old cassette and if not swap it out.

Just remember to check it out on a local loop rather than the weekend epic.

I'll second theotherjonv on having the rings available when you fit the chains and testing them before an epic ride