Chain - To Change or Not to Change...

Just measured my chain on my mountain bike with the park tool thingy and it's dropping in all the way on the 0.75, still fine on the 1.0.

Now, I know in theory that indicates it's time to change the chain now, but so far it doesn't seem to cause any problems.

Would a new chain definitely work with the old cassette? I have used some gears far more than others, so worried that the new chain might end up jumping anyway...(the old one has done about 3,000 miles). Spoke to the lbs over the phone to book the bike in for a service, they said they recommend always changing cassette and chain at the same time - but that means looking at about £50 instead of £10. Problem is, they say the only way to find out if it will slip if only the chain is changed, is to go on a long ride, but with Amsterdame only 2 weeks away and the shop only open while I'm at work, I run the risk of not getting the bike back in there to get it sorted before we leave in case there is a problem (and probably end up paying another chunk of labour charges).

Just wondering if it might be cheaper to ride it into the ground completely and change cassette and change at the same time, but apparently I risk damaging the chainrings as well if I leave it too long.

I probably should be able to do all this myself, but really don't feel confident about it, plus I want to make sure the bike has been checked over professionally before setting off for 250 miles, so lbs it is and the dilemma remains.

What do you think? Change chain only and risk slippage? Change both when they might still be fine for some time and possibly pay a lot of money unnecessarily? Leave it and risk causing damage to the chainrings as well?

I'm stuck - please help!

If it was me, I'd leave it until there was an issue.

I'd change just the chain. If you change it now, you'll get more life out of your cassette.

Obviously, if it skips on your most-used cogs under heavy pressure, you'll also need a new cassette, but I'll be surprised if you do if it only has 3k miles on it.

As you can see, I don't subscribe to the idea that you need to change both at the same time. It's overkill in my experience.

If it shows any sign of stretch, replace the chain. If you wait til there's a problem, there will likely be lots of them, e.g., you may need to replace the cassette, chainrings, etc., as you mentioned. A chain is, what, twenty bucks? The whole system wears together. Changing the chain frequently keeps all your parts happy much longer and saves you money in the long run.

Telling you that it is likely you will need to replace the cassette when you replace the chain is not necessarily true. 3K miles is a good time to do it and chances are you will not have other issues. If you change it and do have other wear issues, you will know right away, and can replace the necessary rear cogs in plenty of time.

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Originally Posted by lunacycles

If it shows any sign of stretch, replace the chain. If you wait til there's a problem, there will likely be lots of them, e.g., you may need to replace the cassette, chainrings, etc., as you mentioned. A chain is, what, twenty bucks? The whole system wears together. Changing the chain frequently keeps all your parts happy much longer and saves you money in the long run.

Telling you that it is likely you will need to replace the cassette when you replace the chain is not necessarily true. 3K miles is a good time to do it and chances are you will not have other issues. If you change it and do have other wear issues, you will know right away, and can replace the necessary rear cogs in plenty of time.

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What she said!

I just had this chat with the LBS wrench on Saturday. That Park took almost drops in at .75 on my chain. He said technically I could wait to replace the chain but if I did it at .75 I would be able to only replace the chain rather than having to replace the cassette, too.

you can have the cassette measured... i forget what my friend used.. it looked like a chain whip... but anyway, you can see if the cogs will be too worn to accept the new chain well.

it is probably better to change it now, particularly if you don't want to change the cassette at the same time.

Hmm...thanks for all your input, looks like the overall consensus is that I could get away with just changing the chain....

Rang another bike shop up today, just for a 2nd opinion, who advised I might get away with it, but would then look at having to change the cassette a year or so down the line anyway, so, overall, they again recommended doing both.

Difference was, the price quoted was less than half of shop number 1, so I might go for it... My friend is taking her bike in tomorrow to get it sorted (same issues), so we see how she fares once they have seen the bikes in the flesh. I let her be the guinea pig - if I'm happy with what they do to hers, mine can follow next week! ;)

Definitely worth changing both if you get a decent quote from your 2nd shop. I left my bike with a stretched chain (ignorance was bliss) a couple of years ago and it very nearly caused an accident. My gears slipped just as I was overtaking a stopped bus - my foot slipped off the pedals, which removed a chunk of calf muscle on the way, and the major wobble that followed ended with me in the middle of the lane just as the bus pulled out without looking. I was lucky enough that it was quiet so I kept it upright and didn't get hit by anything, but I felt pretty silly when I found out that it could've been avoided by changing a few £'s worth of parts out earlier! :o

After another closer look, a lot of the sprockets had developed that sideways wave profile, so it was time for it to go.

Bike went into shop number 2, came out 24hrs later, serviced, with new cassette and chain and a couple of new cables for the grand total of £50 - which is basically the price of the parts! How good is that? :)

A cheap way to check your chain is to get a ruler, and lay it with the zero mark centered on one of the pins in your chain. The 12" mark should also be centered on a pin if the chain is new, or in good condition. If the 12" mark is 1/8" or more past the center mark, then it's time for a new chain -- Now. If you keep an eye on your chain wear, you can avoid replacing cassette cogs and chainrings for some time. A worn, stretched chain will cause your cogs to wear unevenly, and if you leave the worn chain on there long enough for that to happen, a new chain won't fit well on your worn cogs. Sheldon Brown has some good examples (and better advice) on this at http://sheldonbrown.com/chains.html .

The Park chain checker is a good little gauge, but I tend to use the ruler method (my spoke length ruler does the job well) to keep an eye on things down there...

Tom

I put a bunch of miles on my new / used bike in the past few months and the chain started skipping and dropping. I brought it in and had the same convesation with lbs... I decided to do both. Why not? It's cheaper than car repair and I ride the darn thing near every day!

My dh thought it was excessive, though. Oh well. Worth it to me. I'm doing a century next weekend and I want that bike in ship shape.

That's what I thought - doing 250miles next week I just didn't want to take the risk (plus the cassette did look pretty worn). Bike running smooth as a baby's bottom now! :)

I finally changed my chain last night. It was pretty easy with a sram chain. I took her on a whopping 14 mile ride today- I just wanted to be close to home if my work undid itself. :p