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Singlespeed & Fixed Gear "I still feel that variable gears are only for people over forty-five. Isn't it better to triumph by the strength of your muscles than by the artifice of a derailer? We are getting soft...As for me, give me a fixed gear!"-- Henri Desgrange (31 January 1865 - 16 August 1940)

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Old 07-17-14, 03:24 AM   #1
nivv
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Weird chain line, wobbly chain and strange wear on chain ring

So I decided to check my chain line since there was noise coming from the drive chain. The noise is only there on part of the stroke and then comes back in the same pedal position.
Here's an album of the chain line:
Chain line album
The chain line seems to be straight but the chain is wobbly.

I've also noticed strange wear on the chain ring. Here's an album of that: Chain ring albumr [2]
As you can see it is not worn the same way all around the chain ring.

Anyone knows whats up? Is the chain toast perhaps?
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Old 07-17-14, 03:51 AM   #2
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To my eye, that chainline is not straight, but not enough out to cause troubles.
Second, your chain seems to be as dry as anything - it needs lubricant.
Have your checked your chain for sideways flex? Even on a 1/8 chain there'll be a little but if a link or two is tight, you may not get it - this would also cause a tight spot in the chain.

Quite frankly, I this is a lubricate and live with it job.
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Old 07-17-14, 03:59 AM   #3
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Originally Posted by europa View Post
To my eye, that chainline is not straight, but not enough out to cause troubles.
Second, your chain seems to be as dry as anything - it needs lubricant.
Have your checked your chain for sideways flex? Even on a 1/8 chain there'll be a little but if a link or two is tight, you may not get it - this would also cause a tight spot in the chain.

Quite frankly, I this is a lubricate and live with it job.
Thanks! Yeah, I just wiped the old lube off, that's when I noticed the chain ring wear. I've just lubed it up again and waiting to take the excess lube off.

Should there be sideways flex or just a little? What am I looking for?
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Old 07-17-14, 04:17 AM   #4
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1/8 chains are designed for straight chain lines so aren't designed to flex sideways, unlike a 10sp chain which you can tie in knots. However, a chain is made up of lots of little bits so you'll get a little sideways flex. All you're looking for is one point that's tighter than the rest of the chain though to be honest, this'll be more obvious in vertical flex ie, the sort of thing you get when rejoining a chain and the side plates are pushed tight against the roller. The cure will be the same, use your chain breaker to push the side plates slightly apart.

I'm still not convinced you've got a problem though, just something that seems like one.
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Old 07-17-14, 04:37 AM   #5
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Quote:
Originally Posted by europa View Post
1/8 chains are designed for straight chain lines so aren't designed to flex sideways, unlike a 10sp chain which you can tie in knots. However, a chain is made up of lots of little bits so you'll get a little sideways flex. All you're looking for is one point that's tighter than the rest of the chain though to be honest, this'll be more obvious in vertical flex ie, the sort of thing you get when rejoining a chain and the side plates are pushed tight against the roller. The cure will be the same, use your chain breaker to push the side plates slightly apart.

I'm still not convinced you've got a problem though, just something that seems like one.
Okay, thanks for the info. I'm not certain that there is a problem either. But the sound when pedaling puts me off, so that's mostly the reason I'm looking for a problem.
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Old 07-17-14, 05:07 AM   #6
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Seeing you're looking for problems (always a fun game to play on a wet and windy afternoon like it is here), check to see if there is any warping in the chainring or maybe a bent tooth, particularly the ones with funny wear patterns. Probably best to take off the chain and just spin the pedals, watching the chainring from one end.
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Old 07-17-14, 12:17 PM   #7
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fixed it...

Quote:
Originally Posted by europa View Post
...check to see if there is any warping in the chainring or maybe a bent tooth, particularly the ones with funny wear patterns. Probably best to take off the chain and just spin the pedals, measuringthe chainring separation in millimeters from a fixed reference point like the seat tube.
This will also show you where and by how much, if you have to bend it back into shape...
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Old 07-17-14, 12:41 PM   #8
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Quite frankly, I this is a lubricate and live with it job.
Yep. This is all pretty normal.

Is the noise coming from the tight spot? http://sheldonbrown.com/fixed.html#tension
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Old 07-17-14, 03:24 PM   #9
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That looks wonky as heck. Measure the chainline front and rear so you know if it's correct, and if not, you'll know by how much.

What is your gear ratio? It is possible that the same piece of chain hits the same place on the chainring over and over. If you have a warped ring or an overly tight spot in the chain, the sound will repeat uniformly.
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Old 07-19-14, 12:50 PM   #10
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Yep. This is all pretty normal.

Is the noise coming from the tight spot? Fixed Gear Bicycles for the Road
Hm, now when I read it seems that I tighten my chain the wrong way. I normally just pull the wheel back until the chain seems to have the correct tension

Quote:
Originally Posted by SquidPuppet View Post
That looks wonky as heck. Measure the chainline front and rear so you know if it's correct, and if not, you'll know by how much.

What is your gear ratio? It is possible that the same piece of chain hits the same place on the chainring over and over. If you have a warped ring or an overly tight spot in the chain, the sound will repeat uniformly.
My gear ratio is 46/17, so no big gears here. You may be onto something, because the sound is coming on exactly the same place when turning the cranks.


Anyhow, I lubed up the chain and went for a 30 mile ride and it doesn't sound much at all. I can still see that the chain is wobbly when looking straight at it. Haven't been able to see if the chain ring is straight, but my guess is that it is. Unless it was damaged in the mail when I received the bike, since the sound have been there from the start. I'll just order a spare chain and see what happens.

Thanks guys for the help
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Old 07-19-14, 12:56 PM   #11
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This isn't "strange wear" on the chainring. It's perfectly normal.

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