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Worn chain

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Old 12-12-18, 09:01 PM
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MNwj48
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Worn chain

Today I put a new KMC Z50 chain on my 1974 Schwinn Suburban. This is not a question, or dramatic news, but may be of some interest to some, especially if you have not been able to get out due to the snow, or are terminally bored.

So this is the bicycle I normally ride. Rode it Tuesday to the library, through a little snow, temp of 28 degrees F, bit of a 10 to 15 mph headwind coming back.
The chain has been suspect for sometime. It may be the original chain from 1974.
The chain would jump off the main gear every once and a while. I pulled on it at the middle of the large gear, as a test, and the slack is more than half way up the gear teeth.

Tried to by a chain breaker at the shop where I bought the chain, but they did not have any of the ones I wanted. The only had more expensive ones. So I am doing this with a pin punch to push out the chain pins. That takes more time than is reasonable because the chain won't float in mid-air as it needs to. Have to prop it up with a block of wood so I can punch the pin out. If I get a chance I will look for a Park-Tool chain breaker, but I put in a removable link in the chain, and this chain may last 5 years at my rate of use, so I got time.

When I got the chain off I compared the worn chain to the new KMC chain.
Measured over 20 links, the new chain is 154 mm, and the old chain measured 160 mm. That is 6 mm over 20 links, or 0.3 mm of wear per link. The pin on the old chain has a very visible wear notch in it. Overall, the old chain is 31 mm longer than the new chain, measured after shortening the new chain to the same number of chain links.

Put some oil on the KMC chain before I installed it. It seemed to be already greased, but after seeing the condition of the old chain, I feel the need to oil everything, so I did.
I loosened the crank bearings enough to put some lithium grease and about 4 good squirts of zoom oil in there, each side. I put some newspaper under the bike for the next few days, that oil may stay put, or it may drip some.

Got really cold fingers because it is 25 degrees F here and every tool in the garage is sucking the heat out of my hands. It could be worse, and probably will be, as this is Mpls, Minn. This is a warm spell.

I expect this may improve the shifting performance too. Always had trouble shifting to lowest gear. It probably was like trying to push limp spagetti for the Shimano to get that chain over the largest gear.

Got to go back to the library in a few weeks when the books are due. I am hoping for less wind.
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Old 01-15-19, 03:37 PM
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BlazingPedals
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Having such a worn chain didn't damage your gears? I measure 12 full links, and if it measures 12- 1/8", it's past time to replace it and damage to other parts has probably already occurred. Your chain was 3 times that amount of wear. Running a new chain on worn gears will wear out the new chain prematurely.
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Old 01-15-19, 04:05 PM
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79pmooney
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I'll be very surprised if the new chain even works on that old freewheel. If you mean one single 1/2" link when you say "link", that's 9/32" stretch in 12' or over 1/4"! If you mean a pair of links, (1" total) per "link: that's still well over 1/8"; a lot. If this does work, the worn freewheel teeth will rapidly stretch your new chain to match. (ONS - old new stock for you C&Vers. )

You have time. Go to Amazon (or wherever) and get a 14-28 5-speed freewheel (and the remover if you want to do future work yourself). It is highly unlikely that this remover will work to take off the old freewheel (FW hereafter). Take the wheel to a bikeshop to remove the old FW (probably an Atom or Regina; it may also require some real muscle and a big wrench and/or bench vise) unless you want to collect tools or get into the Classic and Vintage mentality/cult . (I cannot claim to be one of that cult but I do ride bikes and gear plenty old enough and have been riding that stuff since it was current and I do hang with a lot of them, on BF and face to face.)

Ben
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