What causes this?
04-18-23, 03:35 PM
#1
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What causes this?
This is from a donated bike so I don't know the history. 1 x 7 schwinn cruiser type bike with the symptom being a "juddery" feeling, present on all rear cogs but progressively worse as you approach the smallest cog. I took the chain guard off to find what is pictured. Chain shows little wear using the chain gauge. I took the chain off and it doesn't have any stiff links. I have checked the RD for alignment and it is OK, and the jockey wheels are running smoothly. I don't have another chain to try; what I think I am feeling is the chain vs. front gear as it leaves the gear. Is this chain shot even though it doesn't show it on the gauge. Thanks!
04-18-23, 03:55 PM
#2
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What you've taken a photo of there is extreme chain wear. You'll also need to replace the freewheel, and honestly i'd take a good hard look at the chainring too.
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04-18-23, 04:39 PM
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+1 on the extreme chain wear. But in the odd chance it is not...It could be a 1/8 (4/32) chainring being too wide for a 3/32 chain.
In either case, a new proper chain is in order.
Cheers.
In either case, a new proper chain is in order.
Cheers.
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04-18-23, 04:53 PM
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an extremely Low Quality Chain, Lousy chain lube(if any) and obvious Neglect.... with a chance of a bent tooth or chainring... but all that offset pictured leads me to think it's that chain... !
set a new chain around the chainring,,, pull it tight.... then try to pull it outwards from the mid point opposite the end... see if it lifts more than 1/2 a tooth height... if so, then the ring is shot.
set a new chain around the chainring,,, pull it tight.... then try to pull it outwards from the mid point opposite the end... see if it lifts more than 1/2 a tooth height... if so, then the ring is shot.
Last edited by maddog34; 04-18-23 at 05:04 PM.
04-18-23, 04:57 PM
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[QUOTE=base2;22864082But in the odd chance it is not...It could be a 1/8 (4/32) chainring being too wide for a 3/32 chain.
In either case, a new proper chain is in order.
Cheers.
[/QUOTE]
Just worn. Observe how the links mesh with the cog at the bottom. If the chain were too narrow, it couldn't have been used long enough to cause elengation, unless, maybe, diabolically, it was worn out on a different bike and then transferred to this one.
In either case, a new proper chain is in order.
Cheers.
[/QUOTE]Just worn. Observe how the links mesh with the cog at the bottom. If the chain were too narrow, it couldn't have been used long enough to cause elengation, unless, maybe, diabolically, it was worn out on a different bike and then transferred to this one.
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04-19-23, 07:56 AM
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Chain ring is worn if you are sure the chain measures within spec. Perhaps the previous chain was used well beyond time to replace and that wore out the ring and probably some of the rear cogs too.
04-19-23, 09:37 AM
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This is from a donated bike so I don't know the history. 1 x 7 schwinn cruiser type bike with the symptom being a "juddery" feeling, present on all rear cogs but progressively worse as you approach the smallest cog. I took the chain guard off to find what is pictured. Chain shows little wear using the chain gauge. I took the chain off and it doesn't have any stiff links. I have checked the RD for alignment and it is OK, and the jockey wheels are running smoothly. I don't have another chain to try; what I think I am feeling is the chain vs. front gear as it leaves the gear. Is this chain shot even though it doesn't show it on the gauge. Thanks!
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04-19-23, 12:26 PM
#8
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Clearly a case of a severely worn chain or chain ring. You say the chain is OK by your chain checker. I suggest getting out a ruler and measuring the chain. It should be less than 1/8" elongated in 12" original length (1% elongation). The current spec is actually 0.5% elongation (1/16" in 12") but with these low quality setups, and 7 speed, 1/8" is OK. You have way more issue than that.
04-19-23, 03:34 PM
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04-20-23, 08:41 PM
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Look this video about the 2:50 mark and will see the tool bouncing off the closer rivet.
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04-21-23, 06:04 AM
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Bicycle: Measuring Chain Wear using a 12-Inch Ruler
The ruler does not lie!
04-21-23, 07:23 AM
#12
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Extremely worn chains may yield a false "good" because the checker is hitting the roller closer to the "hook" end. I always have a steel rule on hand in addition to the chain checker.
Look this video about the 2:50 mark and will see the tool bouncing off the closer rivet.
https://www.youtube.com/watch?v=gXd-3UnqoaM
Look this video about the 2:50 mark and will see the tool bouncing off the closer rivet.
https://www.youtube.com/watch?v=gXd-3UnqoaM
04-21-23, 07:34 AM
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That's an old schwinn, love that Ashtabula crank.
My bad, not a single speed! the front sprocket will be fine, the rear not so much.
My bad, not a single speed! the front sprocket will be fine, the rear not so much.
Last edited by Schweinhund; 04-21-23 at 07:42 AM.
04-21-23, 09:48 AM
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Extremely worn chains may yield a false "good" because the checker is hitting the roller closer to the "hook" end. I always have a steel rule on hand in addition to the chain checker.
Look this video about the 2:50 mark and will see the tool bouncing off the closer rivet.
Look this video about the 2:50 mark and will see the tool bouncing off the closer rivet.
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04-21-23, 11:57 AM
#15
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That checker isn’t showing a “false good” at all. The “bouncing” of the hook end is because the mechanic is moving the checker to illustrate that the chain is worn beyond 0.75%…well beyond at that. The chain checker in that video shows that the chain is obviously worn. The only way that measurement would show a “false good” is if the person doing the measurement didn’t know how the tool worked. No steel rule is needed to further check the results.
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