Chipped teeth on Shimano MF-Z012 6 Speed freewheel.
01-07-13 | 02:06 AM
#1
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From: NYC
Broken teeth on Shimano MF-Z012 6 Speed freewheel.
A little back story:
This past summer I bought my first bike, 1986 Schwinn World Sport. At the time I didn't really know much about what to look out for before purchasing a bike. Maybe 2 months later of owning it, I noticed A LOT of skipping in my cranks while in the third gear. I never even bother to inspect the freewheel to see what was up during that time due to ignorance. Around mid october, I sent my bike in to my LBS to by a new chain a freewheel. When a mechanic took my bike to install everything I hear him yell "DAAAAMMMMNNN!!!" and he runs over to show me this:
I remember saying "So, THATS way my cranks kept skipping...huh"
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Would anyone be able to tell me a few causes to something like this. I'm just curious all of the sudden, didn't think to ask the mechanic when I discovered it.
This past summer I bought my first bike, 1986 Schwinn World Sport. At the time I didn't really know much about what to look out for before purchasing a bike. Maybe 2 months later of owning it, I noticed A LOT of skipping in my cranks while in the third gear. I never even bother to inspect the freewheel to see what was up during that time due to ignorance. Around mid october, I sent my bike in to my LBS to by a new chain a freewheel. When a mechanic took my bike to install everything I hear him yell "DAAAAMMMMNNN!!!" and he runs over to show me this:
I remember saying "So, THATS way my cranks kept skipping...huh"
------
Would anyone be able to tell me a few causes to something like this. I'm just curious all of the sudden, didn't think to ask the mechanic when I discovered it.
Last edited by E_is_Chill; 01-07-13 at 02:11 AM.
01-07-13 | 05:46 AM
#2
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From: England, currently dividing my time between university in Guildford and home just outside Reading
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I've seen a freewheel with a broken sprocket, and also a Shimano cassette with a broken sprocket. The cassette was a decent-quality one, and from what I've heard, the Schwinn World Sport was no department store junker (correct me if I'm wrong on that). As such, I don't think it's always a quality issue. It may be due to pedalling too hard while shifting.
01-07-13 | 01:56 PM
#3
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From: Rochester, NY
Bikes: Stewart S&S coupled sport tourer, Stewart Sunday light, Stewart Commuting, Stewart Touring, Co Motion Tandem, Stewart 3-Spd, Stewart Track, Fuji Finest, Mongoose Tomac ATB, GT Bravado ATB, JCP Folder, Stewart 650B ATB
This type of tooth failure is not too uncommon. I've seem many freewheels of various brands with multipal teeth missing. I always thought it had to do with the hardness level and the stress of shifting. Andy
01-08-13 | 08:53 PM
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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
Given the age and overall condition, especially the amount of rust, I suspect that this might explain this damage. If the bike was left idle for a long time exposed to the elements, with the chain on those teeth, it would have trapped and held water there. So the rust on those teeth would have been much worse, and they might have come apart the first time the bike was moved.
I don't offer this as fact, just a theory.
I don't offer this as fact, just a theory.
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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.
