benjamin163

Hello everyone,
this enforced time in got me tinkering at the weekend and I managed to get my cranks off, do a little clean and replace the chain on my everyday bike.
Question I've got is how do I tell with any degree of accuracy when I should change my chainring and cassette?
I understand that the teeth ware down over time but I'm not expert enough to see what the signs of real ware are and when they are worn enough.
Any help gratefully received.

woodcraft

Chainrings last a long time, they are probably OK.

If you put a new chain on, and it does not skip under hard pedaling, the the cassette is OK.

It's not easy to tell by looking.

This is the simplified answer- much more elaboration will likely follow.

Bill Kapaun

First thing is measure your chain.
I like to measure a 3' section if i have the chain off the bike. It reduces the human error to 1/3.
Wear up to 1/16"/foot is considered acceptable.
At 3/32"/foot, time to replace.
IF the chain is good, it's a promising sign for the cassette/or FW being good.
IF excessively worn, probably not.
Chain rings last much longer, but if the other parts are excessively worn, they will wear much faster.

dsbrantjr

Measuring over 3 feet as Bill Kapaun suggests is great, if it is convenient to remove your chain from the bike, but one should be able to measure to 1/16" accurately with a good 15- or 18-inch steel rule. Here is an inexpensive set with a 15-incher: https://smile.amazon.com/eBoot-Stain.../dp/B071H4XCDW

alcjphil

Well, Gee, how about filling us in about what exact bike you are asking about, how old it is, how many miles you have ridden it. You ask for information about your bike without providing much from your side

benjamin163

Thanks for this answer. Seems like I'm ok then!

benjamin163

Ha, you're right. I posted pictures to help with the enquiry but unfortunately the site doesn't let you post pictures until you have 10 interactions.
Bike is a Hoy Shizuoka, 5 years old but has been fully serviced a couple of times. It is ridden through London 10 miles a day 5 times a week. Chain I replaced was well worn. New one works nicely and no slipping.
I will post a picture of the cassette when I'm allowed. Thanks for the prompt.

benjamin163

Nice succinct answer, much appreciated.

benjamin163

Thank you for this. I have a device which measures chain stretch. a simple tool which you hang one end over a link and if the other end can descend into the chain it needs changing. Do you know it?

benjamin163

I think I'm able to post a picture now, so here it is.
Would anyone here be able to give me an opinion of whether this cassette seems worn or not and what the telltale signs are?

dsbrantjr

I do not trust chain checkers, I have heard too many reports of them showing e.g. 0.5% wear on new chains, which is why I use and recommend a rule/

Moe Zhoost

Good picture. I'd need a closer look at that smallest cog, but the rest look just fine. It looks like you predominantly use just the smallest 4 cogs. As this is the case, you may want to change the rear cassette to one with a narrower gear range.

Good luck

benjamin163

Interesting, thanks for that. I never knew there were discrepancies. I shall invest in a metal rule and do both for safety.

benjamin163

Great shout thank you so much.
I think you're right. I barely ever use first or second gear and I believe I spend most of my time in 5th and higher.
I shall look into how to change it.
Any advice on that?
Is it simply a case of swapping the largest three cogs for three more at the smallest end?
Or is it something to do with counting the teeth on each cog and making the difference in number between each smaller so there's less of a jump?

easyupbug 

If you google worn cassette and then click images you will see 100s of photos of what wear looks like, same for the chainring.

benjamin163

Good shout, I shall do just that.

UKFan4Sure

Why go to all the trouble to remove the chain, when these little tools exist? They should be in every tool box.

UKFan4Sure

I don't trust your reports. I've never had any trouble using one. A chain checker doesn't mysteriously go out of tolerance and suddenly show a 0.5% error. If it does, I'd suspect the chain manufacturer, not the checker. By the time you are having shifting trouble, the tolerance you mention above will be long past that measurement.

Moe Zhoost

You may be able to customize your cassette by swapping rings, but it would probably be easier to buy a new cassette with a more suitable range. Using a larger ring on your crank would be another option. This is not something you have to do, though, and keep in mind that any change may require other changes.

Drew Eckhardt 

They're not accurate because they make assumptions about roller clearance which does not impact pitch change and cog/ring wear.

You're better off with a $1 12" ruler measuring over the first 11" and discarding once the distance between the same point on pins exceeds 11 1/16".

Drew Eckhardt 

No.

It's worn out when a new chain skips on it.

Rings are worn out when the same thing happens or you have uncommanded shifts to smaller rings which can cause a crash when you're standing.

You can also get wear checkers

benjamin163

This is all extremely helpful and I thank you for your suggestions and input.
I've learned a great deal and best of all I've learned I don't need a new cassette yet!
Thank you.

Bill Kapaun

I trust mine implicitly so far.
If it shows a "snug" .5%, I know it's really .25% as verified by ruler.
I haven't seen a worn enough chain to check the .75% side. When I do, I'll also measure that chain with a ruler to give me a 2nd reference point.
That will save a lot of hassle fussing with a straight edge when a quick check will show many chains are still "quite good".
You just have to know your tools.

AndrewJB

As a general guide...When your chain ring looks like this...you might want to think about replacing it...
This was on a 2008 Trek 2.3 I bought at a garage sale several years back. Couldn't get around the block without the chain coming off.
I could have just replaced the ring, but decided to replace the 105 BB & Crank with new Ultegra BB & Crankset.

noglider 

Some trust chain checkers. Some don't. You can use a ruler. And you can guess. If you guess your chain needs replacement and you replace it, even if it is not completely worn, it's not a bad thing, because if you keep your chain "fresh" you will reduce wear on your cassette. I'd rather replace four chains than a chain and a cassette. Besides, when a chain gets hopelessly dirty, the prospect of changing the chain becomes brighter, and it's always a pleasant ride after I replace a chain.

Also, lube your chain frequently, according to the lube you use. Light lubes need frequent replacement, and heavier lubes less frequent. Keep the chain clean with a rag, and lube and wipe after the chain gets wet. I use heavy lube, but it's a religious topic, and your choice is up to you.