Knowing when chain needs tightening

joah

A bit of a basic question here, how does one know when the chain has become looser and needs tightening/replacing?

Thanks,
Josh

JBA

You can't tighten a chain. Once it has stretched it needs to be replaced.
You can judge when it needs replacing by measuring the distance between rivets but that is fiddly. The easiest way is with a chain checker like THIS.

This Park Tool video gives a good explanation of when to change a chain.

joah

Thanks JBA.

s_j_pwmb

If you don’t have a chain-wear gauge then grab a chain-link between thumb and forefinger and pull away from the front of the largest front chainring. If you can lift the link clear of the teeth then the chain is very worn, if you get less than half a tooth showing then you’re probably ok.

Do remember that a worn chain will damage the cassette and front chainrings, both of which are significantly more expensive than a chain, so proactive chain replacement is a good idea!

steve_sordy

If you have left it too late, then the new chain may not run on your front ring(s) or your cassette.

With the front rings, the problem will be chain suck, where the chain seems to stick to the ring. Instead of the bottom strand carrying on towards the cassette, it travels around the ring and jams. It can damage to frame, jam in between the rings or at worst can have you off the bike. This usually happens when the teeth on the rings are worn as well.

With the cassette, the chain will jump when you put the power on. It's not a pleasant feeling or sound!

If you don't want to buy a chain checker, you could remove the chain and check with a metal tape measure. If you use a magic connecting link, this is easy, other wise you will need to a chain breaker and a fresh rivet to refit the chain.

Lay out the chain on a flat surface, like your kitchen worktop (use newspaper!), with the sideplates uppermost so that you can see the pins. Stretch out the chain and measure the length of 100 links. A new chain will measure 50" bang on. It will be helpful if someone else could hold the idiot end of the tape so that one of the inch markers (say 10" to make the sums easy) exactly on to the centre of one of the pins. If your chain is scrap (1% or more), then 100 half-inch links will measure 50-1/2" or more!. At this level your cassette may also be scrap, and maybe one or more of your front rings. 50-3/8" is 0.75% and that is the normally accepted urgent replacement point. 0.75% is one of the indicators on a chain checker that you can buy. Anything less than that and you are OK, the closer to 50" the better.

joah

Thanks a lot everyone. Chain is fine it turns out! But good to know how to keep an eye on it. How often do you check on average? I'm sure it depends how much one cycles, but assuming a few hours cycling every week, would every few months be ok?

reaperactual

Let my chain wear too far to the point that new chain wouldn't mesh with the equally worn cassette.

Stuck the old chain back on carried a spare missing link and chain tool and decided to run it into the ground then replace whole drivetrain as soon as I hit any future problems.

Carried on for another 12 months without any noticeable issues so I replaced the whole lot to sell the bike and it rode like new again.

steve_sordy

reaperactual said:

Let my chain wear too far to the point that new chain wouldn't mesh with the equally worn cassette.
.....................
Carried on for another 12 months without any noticeable issues so I replaced the whole lot to sell the bike and it rode like new again.

I was waiting for you to write that it rode so well you decided not to sell the bike!

reaperactual

Lol! It was a previous mountain bike. Loved it but was very entry level and needed to make room for my new one. Sold it to my friend and seeing as I will be maintaining it for him in future I made sure it was tip top before selling.

Unlike you Steve it was a Whyte that I didn't regret selling! 🤣😂