Dolphin North

Hi everyone,
I'm new here but I'm hoping for some help. On my hybrid bike I currently have a 7 speed cassette (Shimano Hyperglide something or other) and the chain is 118 links. Starting to skip and I tried tightening the little back screw for more tension but no luck, so I'm going to get a new chain. The chain checker falls in easily at 0.75 but not yet at 1, so I think that still means the chains is getting worn out, right? I'll put off a new cassette for now and see if the chain is enough. Good idea?

My main question is this:
I see on the Internet that 7 speed chains are often 114 to 116 links and most chains I see on Amazon are 116 links for a 6/7/8 speed. I only found one that has 118 links. I see a lot of 11 speed chains have 118 links so I don't know which is more important, the speed rating or the actual number of links? Would replacing my 118 link chain with a 116 work? Or should I buy the only 118 link chain I can find that is 7 speed rated?

dedhed

Your existing chain is probably too long.

​​​​​​https://www.parktool.com/en-us/blog/...-length-sizing

Andrew R Stewart 

Since we don't know how the OEM chain length works with the rear der, the cog tooth count spread, the ring tooth difference and the chainstay length I don't think I can offer specific advice as to the best link count.

However one can try to experiment with the OEM chain still on the bike by shifting to the big/big cog/ring combo and then wind up a pair (or two) of links to see how the rear der cage handles the shorter chain. Doing this hand/finger wind up keeps the bottom of the chain (where that rear cage is) from being affected by any side to side displacement (as you wrap those links over your fingers). If you can't get the chain links to wrap up/fold over w/o the cage being totally played out you have that part of your answer. If you can than a shorter chain might be OK.

I often will try a few tricks or manipulations of the system before removing any part of it to see what are the limits before I can't (as in the chain is removed). How does the system shift, how much remaining rear cage play out is present in the big/big, any pulley knock, does the cage wind up so far that the chain droops in small/small.

Years ago some chains were available from suppliers in a spool many bikes' worth long. One would determine the length, add one link for that fudge and cut only that amount off the spool of chain. Now with chainstays and cassettes becoming really big the aftermarket chain packaging is often not sufficient. Andy

FBinNY 

Start by seeing if your system can use a shorter chain, and estimate minimum chain length.

Shift to the big/big combo. Then hold the cranks and pull the lower loop forward, off the bottom of the chainring, and reattach it with the excess at 3 or 4 o'clock. Now count how many links are unnecessary, and shop chains accordingly.

FWIW - 118 links seems unusually long, so unless you have a super large cassette with over 30t, I strongly suspect that a stock 114 link chain will work.

Lombard

Those chain checkers can be wildly off. To accurately measure chain wear, use a 12" ruler as described below:

https://www.bikeride.com/chain-wear/...ar%20sprockets.

A worn chain doesn't generally warn you with ghost shifting because your chain and cassette effectively "marry each other". IOW, a worn chain eats into your cassette. A new chain on a badly worn cassette will definitely cause shifting problems.

Iride01 

If you are absolutely certain the old chain is the original chain and was correctly sized, then you can just break the new chain at the same length. If you do in fact need more links, you can buy a second chain and use links from it every time you have to replace a chain. Or if just one or two is need, it probably won't hurt to use links from the old chain unless you put a lot of miles on your bike annually.

Most bike chains need to be shortened from what they are sold as. There are several ways to size a chain to a bike. Usually for Shimano and others, they say to wrap the chain around the big front and big rear and don't go through the rear DR cage. Then from where they meet add 1 to 2 full links. Pay attention to whether you are using a quick link or a pin. As you'll have to break the chain in a different place.

Telling us what brand and model bike you have as well as the brand and model components on it will let us give better answers instead of generalizing that often is correct, but not for every bike out there.

mr_pedro

The chain needs to be rated for 7 speed, the determines the width of the chain and you should not mix with other types.
For what length is concerned, normally you buy a chain that is too long and then cut it down to the size needed.
here is an online calculator to get an indication of what length is needed: https://www.omnicalculator.com/sports/chain-length

Dolphin North

Well I have read all of your responses and thanks to all of you for your help! I also watched the video provided and then one that was linked to the first video. Turns out, my chain is too long for the bike and is worn (I verified with a ruler to be sure). Strange because it is the original chain on the bike and I bought it new. Maybe someone at the bike shop got chains mixed up because it is a Shimano derailleur and cassette, but not a Shimano chain, but definitely 118 links is too long as FBinNY said. When I go to the 2 smallest sprockets the chains does rub on itself in the derailleur, which I never noticed as I don't use that combo ever. Strange this can happen on a new bike from the shop though.

From pinching off 4 links I see the chains still has 2 slight bends in it in the cassette so I can probably go down to 114, but I think I'll order a 116 and start with 116 links. Easier to knock out a pair of links than to add a pair.

Does the number of links affect shifting or should I expect to be able to just put the chain on and ride as is (as long as I have a 7 speed chain)?

Thanks again.

Iride01 

Yes, it can.
Maybe. You can likely ride it. But possibly it will shift better than ever, or it might need some adjusting.

Just get the chain installed and lets not speculate about the possibilities until there is a problem you can experience and describe.

Lombard

Probably not. Older hybrids often had mismatched components. My 2002 Cannondale Silk Adventure had a Shimano chain, rear derailleur and brake calipers, a SRAM cassette and shifters, a Nexus front derailleur and a Sugino crankset. It was a 3x8 drivetrain. Older drivetrains were less finicky overall.

alcjphil

Don't be surprised if your cassette also needs to be replaced

dedhed

6/7/8 speed chain is all the same. Changes happen at 9 and above.

Rarely will you see a Shimano chain as OEM from the factory. Most people will run KMC, SRAM or other brands when replacing chains. Most of the major chain manufacturers have a few levels of chain in different price ranges and features. Nearly all run some sort of quick link rather than pushing a pin in to reconnect.

Dolphin North

Yes I am half expecting that. I was planning to do both but I'm going to just do the chain first as it was exactly 1/8" off of 12" when I measured with the ruler as suggested above.So this could go either way. I already have a replacement cassette with the same number of teeth picked out if I need it.

Dolphin North

Yes this was a KMC and that is what I ordered. The original didn't use the "missing link" but the new one will.

Lombard

This sounds wise. The worst that can happen is the new chain will skip with the old cassette.

Bill Kapaun

This is how I estimate chain length in situ.
Put in on the largest ring & cog- (forgot that part before edit)
You want between 1-2" of "slack". Your 5* 1/8" (approx) wear will translate to a 1/2 link+, so compensate.
Pull snug without forcing.
This method keeps the hands relatively clean.

Dolphin North

^^^^ Good hint. Yeah my hands were a mess yesterday!

Lombard

Hmmmm. Don't you mean the smallest ring and cog? I believe this is how Shimano recommends sizing a chain. You should then cut the chain down to where it just barely has tension and isn't slack.

Latex or nitrile gloves keep the hands clean.

grumpus

But an actual 6 speed chain, or 5/6 speed (if you happen to find one) won't run on a 7 or 8 speed cassette - the pins stick out too far past the plates. A chain labeled 7 speed will run on 6/7/8 speed cassettes. An 8 speed chain will also run on 6 and 7 speed cassettes, so is often labeled as 6/7/8 speed.

dedhed

That may well be, but every manufacturer designates 6/7/8 speed, is the generally accepted norm, and in practice works fine in the vast majority of applications.

Hondo6

Well, Park Tool recommends big/big.

https://www.parktool.com/en-us/blog/...-length-sizing

I believe Shimano does too, but I'm not going to search through their tech docs right now to verify.

grumpus

Two ways to size a chain:
Put it on big/big (not fitted to the derailleur) and add a link or two of slack. That's the shortest it can be and not lock up if you ever shift to big/big.
Put it on small/small (fitted normally to the derailleur) and remove the fewest links possible to put some tension/rotation on the derailleur cage.
You can make it even shorter if you never use big/big, or longer if you're never in small/small, but you'd only do that if you were short on capacity e.g. using a shorter cage with 3X.
Longer chain may help shifting (depends on cage geometry) shorter can improve chain control over rough ground and anywhere between should usually work fine.

grumpus

I believe I just stated that. I was simply clarifying that "6/7/8 speed" is a designation of a particular chain size, it doesn't mean that original 6 speed chains are interchangeable with 7 speed or 8 speed.

Bill Kapaun

No.
Ignore list

LV2TNDM

1/8" stretch in 12" will require a new cassette in almost all circumstances. 1/16" stretch is the threshold.

And skip caused by a new chain not meshing with an old cassette is caused by pedaling under load. You need to check all cogs and apply high load to the pedals. Careful because it will most certainly skip in one or more of the smaller cogs. I disagree about the shifting replies. An new chain will usually shift just fine on an old cassette. It's chain tension on the old cogs that causes the problem, and has nothing to do with cog spacing or chain width or the rear derailleur's function, assuming replacement parts are the same spec. (That said, anytime you replace anything on a bike, you HAVE to confirm all adjustments are correct. Never assume, for example, that rear derailleur limit pins don't need adjustment after making a change. Be safe, check and confirm.)

PS "Stretch" = "elongation" but no one uses the latter term, despite the former being a misnomer.