chain stretch
08-13-14 | 12:27 AM
#1
Thread Starter
Senior Member
Joined: Apr 2010
Posts: 817
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From: New York City
chain stretch
I bought the Park Tool to check for chain stretch and lo and behold all my chains are too long.My tool has a .5 and .7 readings and the .7 side easily enters the chain.Does that mean replaceing the freewheel with the chain is mandatory?Strangely enough the chains don't slip and shift fine.
08-13-14 | 12:31 AM
#2
Lance Legweak
Joined: Apr 2009
Posts: 881
Likes: 29
From: Woodland, California, USA
Bikes: Felt Z-70, GT RTS-2
You need to check the teeth on the chairing and the freewheel. If they look curved and more like a sharks tooth, then you need to replace the chain and the gears. If you don't, a brand new chain will wear out quickly and then it may break and you'll be stranded. If the gears look wore out, change them with the chain.
08-13-14 | 01:13 AM
#3
Senior Member
Joined: Apr 2009
Posts: 39,897
Likes: 3,865
From: New Rochelle, NY
Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
A chain and sprocket will work fine together until about 2% stretch, but if the chain is stretched much beyond 1/2% stretch, a replacement chain is likely to skip on the used sprockets.
Given that you've passed the "safe" replacement mark, odds are you'll need a new cassette if you replace the chain.
You have 2 choices here.
1- do it the old fashioned way, and keep riding until the chain begins to slip.
2- buy a new chain and cassette, but install only the chain and cross your fingers. If it runs on the old cassette, save the new one for next time. If it skips, replace the cassette.
Given that you've passed the "safe" replacement mark, odds are you'll need a new cassette if you replace the chain.
You have 2 choices here.
1- do it the old fashioned way, and keep riding until the chain begins to slip.
2- buy a new chain and cassette, but install only the chain and cross your fingers. If it runs on the old cassette, save the new one for next time. If it skips, replace the cassette.
__________________
FB
Chain-L site
An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
FB
Chain-L site
An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
08-13-14 | 05:47 AM
#4
Mechanic/Tourist
Joined: Apr 2007
Posts: 7,522
Likes: 12
From: Syracuse, NY
Bikes: 2008 Novara Randonee - love it. Previous bikes:Motobecane Mirage, 1972 Moto Grand Jubilee (my fave), Jackson Rake 16, 1983 C'dale ST500.
No need to add to FB's advice to the OP, but I will add a couple precautionary notes to others dealing with possible drive train wear:
You don't need a tool to check for wear. It's a waste of money for a consumer, with the possible exception of someone who has a stable of bikes. All it takes is a ruler, which is far more accurate - one can find multiple examples on the forum where someone's gauge said the chain was worn more than it was. The fact that a tools exists does not mean it is useful for everyone. Google measure bike chain wear.
Don't depend on your eyes to detect cassette wear - it happens before even the sharpest eyes can detect it. The test is how a new chain behaves, or how the cassette works when switched to a different bike that has an unstretched chain.
Chainrings can become less efficient long before they get to the shark's fin stage, but of course it's a matter of utility vs. budget as to when you replace them.
You don't need a tool to check for wear. It's a waste of money for a consumer, with the possible exception of someone who has a stable of bikes. All it takes is a ruler, which is far more accurate - one can find multiple examples on the forum where someone's gauge said the chain was worn more than it was. The fact that a tools exists does not mean it is useful for everyone. Google measure bike chain wear.
Don't depend on your eyes to detect cassette wear - it happens before even the sharpest eyes can detect it. The test is how a new chain behaves, or how the cassette works when switched to a different bike that has an unstretched chain.
Chainrings can become less efficient long before they get to the shark's fin stage, but of course it's a matter of utility vs. budget as to when you replace them.
Last edited by cny-bikeman; 08-13-14 at 06:10 AM.
08-13-14 | 08:47 AM
#5
Senior Member
Joined: Dec 2010
Posts: 8,951
Likes: 14
Not only is a chain measuring tool a waste of money, it doesn't properly measure chain elongation. If you're interested, here's a good writeup on it: https://pardo.net/bike/pic/fail-004/000.html
I use and recommend an 18" steel machinist's rule. These are thin stainless steel with fine scribed markings which makes accurate measurement easier. The pix below show a chain exhibiting 1/16" elongation over 12" (13"-1"= 12"). I start from the 1" mark because the scribes on both sides of 1" help center it on the pin.
I use and recommend an 18" steel machinist's rule. These are thin stainless steel with fine scribed markings which makes accurate measurement easier. The pix below show a chain exhibiting 1/16" elongation over 12" (13"-1"= 12"). I start from the 1" mark because the scribes on both sides of 1" help center it on the pin.
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