So I went to get my bike tuned up today and the guy said my chain should be replaced because it was stretched half a cm and if I didn’t then I would need a new cassette later.
Is this a real thing? I’ve never heard of this before.
I think that the chain - does not really stretch - rather the pins wear and cause it to get longer - usually a sign it needs replacing - now I know the metallurgists et.al. on the list may hold a different opinion 
So I went to get my bike tuned up today and the guy said my chain should be replaced because it was stretched half a cm and if I didn’t then I would need a new cassette later.
Is this a real thing? I’ve never heard of this before.
Technically it’s worn rather than stretched but that difference is considered nit picking by many. Yes if our chain is actually worn 1 cm it’s past time to replace it or it will quickly wear out your cassette as well as chain rings.
Hugh
So I went to get my bike tuned up today and the guy said my chain should be replaced because it was stretched half a cm and if I didn’t then I would need a new cassette later.
Is this a real thing? I’ve never heard of this before.It’s common to measure 12 links with a steel 12" ruler and replace when the chain ‘streches’ to 12 1/16 or 12 1/8". 1/2cm over the whole chain is getting close to 1/16" over 12" so it’s probably a good time to change it.
So I went to get my bike tuned up today and the guy said my chain should be replaced because it was stretched half a cm and if I didn’t then I would need a new cassette later.
Is this a real thing? I’ve never heard of this before.It’s common to measure 12 links with a steel 12" ruler and replace when the chain ‘streches’ to 12 1/16 or 12 1/8". 1/2cm over the whole chain is getting close to 1/16" over 12" so it’s probably a good time to change it.
So how much should a chain cost? Is there any difference in chains? I’m a BOP recreational racer so one nanogram of weight or aerodynamic edge doesn’t really make a difference to me.
Here is the ULTIMATE info page for chain wear.
http://pardo.net/bike/pic/fail-004/000.html
Me, I just say if the pins are visibly more than 12 in. apart - it’s time for a new chain.
Cost depends on the chain.
What kind of components do you have? Usually its not a bad idea to get a chain that is designed for your drivetrain.
And don’t just trust the mechanic. Get a precise steel ruler. Measure from center of pin to center of pin when the chain is on the big ring and under mild tension. If it looks like the chain is 1/16" or more ‘stretched’ (not a good term, but its commonly accepted) over those 12", then toss it in the scrap metal recycling bin. Get a new chain.
You can also get a chain checker type tool to check for chain wear, but most of the ones on the market are fatally flawed in their design (except at least one).
first, if you keep the thing clean, oil it and wipe the excess oil off it will last a lot longer than a filthy chain covered with oily grime.
That said, a 10 speed chain is maybe 20-30 bucks, the more expensive ones might last longer. If you don’t have a chain tool, they are maybe 10 bucks, it’s smart to learn to use one and carry it while training, especially if you ride in the woods.
with the tool, installing a chain is quite simple, many chains (not shimano) use a masterlink you fit by hand, the shimano use a pressed in link that generally works fine
once you have the new chain on, put the bike in your favorite gear and pedal real hard and see if it skips, if so go buy a new cassette, lockring tool and chain whip and take 5 minutes to learn to use these tools.
All those tools are worth owning.
I think that the chain - does not really stretch - rather the pins wear and cause it to get longer - usually a sign it needs replacing - now I know the metallurgists et.al. on the list may hold a different opinion
This is correct. The load on the plates is within the elastic range of the steel. The wear is at the pins/bushings.
The ruler measurement is an easy way to see if the chain needs to be replaced.
Cost depends on the chain.
What kind of components do you have? Usually its not a bad idea to get a chain that is designed for your drivetrain.
And don’t just trust the mechanic. Get a precise steel ruler. Measure from center of pin to center of pin when the chain is on the big ring and under mild tension. If it looks like the chain is 1/16" or more ‘stretched’ (not a good term, but its commonly accepted) over those 12", then toss it in the scrap metal recycling bin. Get a new chain.
You can also get a chain checker type tool to check for chain wear, but most of the ones on the market are fatally flawed in their design (except at least one).
I have Ultegra components.
What is the fatal flaw in the chain checker tools?
Cost depends on the chain.
What kind of components do you have? Usually its not a bad idea to get a chain that is designed for your drivetrain.
And don’t just trust the mechanic. Get a precise steel ruler. Measure from center of pin to center of pin when the chain is on the big ring and under mild tension. If it looks like the chain is 1/16" or more ‘stretched’ (not a good term, but its commonly accepted) over those 12", then toss it in the scrap metal recycling bin. Get a new chain.
You can also get a chain checker type tool to check for chain wear, but most of the ones on the market are fatally flawed in their design (except at least one).
I have Ultegra components.Any chain from that KMC, Wipperman and SRAM say will work with your components will be fine.
What is the fatal flaw in the chain checker tools?Conceptually, a chain checker should be checking the distance between two parts of the chain that drives the gears. Most chain checkers check the distance between a part of the chain that drives the gears and a part that does not.
In practice, I don’t think this matters much - the chain checker can still give a sense of relative wear.
What is the fatal flaw in the chain checker tools?
It is more like the common tools are conservative with regards to chain wear because of the way they measure the chain.
The details can be found here: http://pardo.net/bike/pic/fail-004/000.html
“So how much should a chain cost? Is there any difference in chains? I’m a BOP recreational racer so one nanogram of weight or aerodynamic edge doesn’t really make a difference to me.”
The chain isn’t really “stretching”, the pins are wearing a little and the holes in the plates that the pins go through are wearing, so they become oval instead of round. Thing is, a chain costs ~$30, and a cassette costs $50. If you don’t replace the chain, then your cassette is indeed going to wear faster, but in my experience you are going to get up over 10,000 miles before shifting starts to be negatively impacted if you just leave the same chain and cassette on. I think the chain hits the range where a bike shop will recommend your replace it after around 1500 miles. (I’m pretty sure there are some bike shops that if you put a brand new chain on and brought it in they’d tell you it needed to be replaced) You can do the math for yourself, but you will very quickly pay for the chain tool and the cassette removal tool if you do these jobs yourself, and they are not hard jobs to do although you will get your hands dirty.
Replacing chain/cassette has to be one of the bigger profit makers for an LBS service dept.
FWIW, the reason the cassette wears quicker with a “stretched” chain is that the teeth on the cassette are spaced so that a fresh chain will contact each tooth of the half cassette it is wrapped around. So, when you are in your 12t cog in the back, the chain is hitting 6 of the teeth. As the chain stretches, most of the load will be on the very first tooth that the chain hits on the cassette…6X as much as when the load is spread out over the entire half wrap around the cassette. For a visual of this, go to this site and scroll down to the part “Chain and sprocket wear” about half way down.
http://sheldonbrown.com/chains.html
Personally, I replace my chain and cassette every year after the roads clear up in the Spring. I would estimate I get about 8,000 miles between switches, and have never had a problem with shifting. My first bike had tiagra components and I got 20,000 miles before replacing anything. The one caveat would be that I use the same chain/cassette combo, and thus they wear together. If you try putting a new chain on a worn cassette you will likely have issues, so if you have more than one wheelset you are using on a bike, you might want to change your chain more frequently so it works with different cassettes on all your wheelsets…or just switch your cassette to the other wheelset.
first, if you keep the thing clean, oil it and wipe the excess oil off it will last a lot longer than a filthy chain covered with oily grime.
That said, a 10 speed chain is maybe 20-30 bucks, the more expensive ones might last longer. If you don’t have a chain tool, they are maybe 10 bucks, it’s smart to learn to use one and carry it while training, especially if you ride in the woods.
with the tool, installing a chain is quite simple, many chains (not shimano) use a masterlink you fit by hand, the shimano use a pressed in link that generally works fine
once you have the new chain on, put the bike in your favorite gear and pedal real hard and see if it skips, if so go buy a new cassette, lockring tool and chain whip and take 5 minutes to learn to use these tools.
All those tools are worth owning.
How hard is it to change out? Is it worth the 8 bucks labor to have the LBS do it? (I’m not handy and changing a tube is still about 10 minutes for me, but that is significantly improved with practice.)
How hard is it to change out? Is it worth the 8 bucks labor to have the LBS do it? (I’m not handy and changing a tube is still about 10 minutes for me, but that is significantly improved with practice.)
Suppose you’re on a run and you get a rock in your shoe or your shoelace becomes untied. Would you stop and fix it or would you limp along or abandon your run?
Same thing applies to your bike. It’s not a unicorn - if something breaks on a ride and especially on a long distance race, you need to know how to fix it. Get to your LBS, have them advise you on a chain breaker tool, and then practice using it on an old chain until you get the hang of it. If you then ever do something that breaks a chain in a ride or race, you’ll be able to make the repair and keep going - worst case it’s a five minute setback, and the recovery you get during that break will speed you up on the run.
Chains are held together with a bunch of pins that are press fit into the metal plates. The purpose of the chain tool is to drive the pins out of the chain.
Take a picture of the chain routing for the rear wheel before you start.
To keep things simple, the best course would be to buy the chain tool and something like and Sram chain that comes with a master link. Press the pin out of any link on your existing hain and use it to determine the length of the new chain, then remove the pin on the new chain so the length is right and you are left with two narrow links. Be patient with the chain tool, it’s easy to break the extractor pin if you force it
Look at the picture and thread the chain back through the pulleys and take a minute to make sure it’s correct. All of us have messed it up before.
I like to put the RD on the smallest cog and leave the chain off the front ring so there is no spring pressure on the chain
Make sure the masterlink is fully closed, sometimes you have to grab the chain and flex it side to side a little so it seats.
It is something you can master quickly and is worth learning. People do it on the side of the trail in MTB races all the time.
Cost depends on the chain.
What kind of components do you have? Usually its not a bad idea to get a chain that is designed for your drivetrain.
And don’t just trust the mechanic. Get a precise steel ruler. Measure from center of pin to center of pin when the chain is on the big ring and under mild tension. If it looks like the chain is 1/16" or more ‘stretched’ (not a good term, but its commonly accepted) over those 12", then toss it in the scrap metal recycling bin. Get a new chain.
You can also get a chain checker type tool to check for chain wear, but most of the ones on the market are fatally flawed in their design (except at least one).
I have Ultegra components.
An ultegra chain would be your best choice, but a shimano 105 level chain would be fine too. (SRAM chains seem to have a far less reliable reputation, although I personally have not used one. But even pro teams seem to avoid them.) When you get an ultegra chain, make sure you get the right one (9-speed, 10-speed, 11-speed) for your drivetrain. Prices on ultegra and 105 chains are very reasonable.
What is the fatal flaw in the chain checker tools?
Other have posted this link with full details:
http://pardo.net/bike/pic/fail-004/000.html
This is not a trivial problem because a chain checker tool that makes you throw away a perfectly good chain will cost you unnecessary money and cause waste.
Chains are a very interesting consumable part. Age plays no part in their wear. A chain could be on your bike for 100 years and still be perfectly good (assuming zero corrosion). There is zero reason to toss a chain every season or “every x-thousand miles”. Because chain wear varies hugely with use, environmental conditions, types of terrain you ride, how hard or how easy you ride, duration of use, load during use, the weather, how much you lube the chain, the list goes on and on.
You want to replace a chain when it actually shows some wear (or “stretch”). Not before. Otherwise you are tossing out a perfectly good manufactured bike part. Which, to me, seems kooky.