Middle cog broken tooth
03-26-21, 07:33 AM
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Middle cog broken tooth
So I noticed a broken tooth in the middle cog of a 5 speed freewheel on my 1980 Miyata while chain lubing. It has the uniglide design I think, where the teeth are a bit twisted is all. This is a NOS freewheel I put in about two years ago and there is no other wear or issues. My question is, do I need to worry about this or can I just forget about it? I don't notice it while riding (I use that gear to get up small hills and rises or against strong headwinds).
03-26-21, 07:48 AM
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How far have you ridden in those last 2 years? Have you ever changed the chain since you installed the freewheel? If the chain is worn it may slip on a new freewheel. If it wears too much it will start to wear your chainrings
03-26-21, 07:51 AM
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It will shift easier.
if it was one of the two smallest cogs, seek out a replacement
if it was one of the two smallest cogs, seek out a replacement
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03-26-21, 10:13 AM
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03-26-21, 10:22 AM
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I've had a SunTour cog lose a segment BITD. This was a span of a few teeth. I was able to replace the cog, since SunTour cogs were available in shops back then.
The loss of a tooth or teeth suggests a manufacturing flaw in that cog. There's no reason that other teeth might not break off too. You might be able to continue to use this freewheel, but it would be good to have a replacement freewheel (or cog) on hand.
Steve in Peoria
The loss of a tooth or teeth suggests a manufacturing flaw in that cog. There's no reason that other teeth might not break off too. You might be able to continue to use this freewheel, but it would be good to have a replacement freewheel (or cog) on hand.
Steve in Peoria
Last edited by steelbikeguy; 03-26-21 at 11:24 AM.
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03-26-21, 10:49 AM
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So I noticed a broken tooth in the middle cog of a 5 speed freewheel on my 1980 Miyata while chain lubing. It has the uniglide design I think, where the teeth are a bit twisted is all. This is a NOS freewheel I put in about two years ago and there is no other wear or issues. My question is, do I need to worry about this or can I just forget about it? I don't notice it while riding (I use that gear to get up small hills and rises or against strong headwinds).
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"Far and away the best prize that life offers is the chance to work hard at work worth doing." --Theodore Roosevelt
Capo: 1959 Modell Campagnolo, S/N 40324; 1960 Sieger (2), S/N 42624, 42597
Carlton: 1962 Franco Suisse, S/N K7911
Peugeot: 1970 UO-8, S/N 0010468
Bianchi: 1982 Campione d'Italia, S/N 1.M9914
Schwinn: 1988 Project KOM-10, S/N F804069
"Far and away the best prize that life offers is the chance to work hard at work worth doing." --Theodore Roosevelt
Capo: 1959 Modell Campagnolo, S/N 40324; 1960 Sieger (2), S/N 42624, 42597
Carlton: 1962 Franco Suisse, S/N K7911
Peugeot: 1970 UO-8, S/N 0010468
Bianchi: 1982 Campione d'Italia, S/N 1.M9914
Schwinn: 1988 Project KOM-10, S/N F804069
03-26-21, 11:55 AM
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Thanks for the mention. 
Unfortunately for the OP, I sold my home and downsized last fall, and all the spare parts for freewheels had to be put in storage for the winter. I probably won't be fully reopened until next fall and all I can do is normal cleaning and service at this time.
Depending on the specific model, I probably do have a replacement sprocket buried deep in the storage unit. However, the best I could do is help the OP see if a match can be found on ebay or Loose screws and talk them through a swap. PM me for my email address if you'd like.
Unfortunately for the OP, I sold my home and downsized last fall, and all the spare parts for freewheels had to be put in storage for the winter. I probably won't be fully reopened until next fall and all I can do is normal cleaning and service at this time.
Depending on the specific model, I probably do have a replacement sprocket buried deep in the storage unit. However, the best I could do is help the OP see if a match can be found on ebay or Loose screws and talk them through a swap. PM me for my email address if you'd like.
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Enjoying the GA coast all year long!
Thanks for visiting my website: www.freewheelspa.com
Bob
Enjoying the GA coast all year long!
Thanks for visiting my website: www.freewheelspa.com
03-26-21, 02:20 PM
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Thanks all, I'm sensing at this point I should not just tolerate the broken tooth and forget about it. The freewheel is a Shimano Z012 5 speed that I put in two years back when the original started acting up. It is the 20 tooth cog. I check the chain for wear at least a couple times a year, I have about 5000 miles on it and I cannot yet find any stretch in it (I'm pretty meticulous on maintenance). No trouble is noticed in any gears.
I have a modern Sunrace on hand, with the modern hyperglide teeth, seems like cheating...
I have a modern Sunrace on hand, with the modern hyperglide teeth, seems like cheating...
