Chain strangeness

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Chain strangeness

Postby drifte » Mon Nov 26, 2012 1:51 pm

I recently paid Scheels of Coralville to give my bike the "$40" tune up and put on a new chain. Since then, my bike has been constant problems. Each gear is found easily, but ones put under load all it wants to do is skip. A couple times I looked down and could see the chain when acting up bunch up on the crank sprocket. Is it possible its the wrong length chain? I had no issues prior, but my chain came apart on one ride earier this year ( I fixed it) so I went ahead and had them replace it.

Any advice? Im afraid its going to damage the teeth on my sprockets. And I really dont want to take it back to scheels.
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Re: Chain strangeness

Postby greenfast » Mon Nov 26, 2012 5:42 pm

How old is the bike? Was it the original chain? Does it only do it on one of the front chainrings and is ok on the others?

Either the cassette is worn out but that would happen not necessarily in all gears as the most used ones would be worn, but I would lead towards front chainring being worn. I had a similar thing happen on my road bike as I wore out the big ring a couple years ago and would skip under load while standing and such. Take a look at the teeth on the chainring and see if they are thinner and more pointy then usual.
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Re: Chain strangeness

Postby drifte » Tue Nov 27, 2012 9:03 am

Thanks, will do.
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Re: Chain strangeness

Postby Farmboy » Tue Nov 27, 2012 11:12 am

I agree with greenfast. If under load it's making a "clunk" type of skip, it's likely worn chainring/cassette issues. Look at the teeth and see if they look like shark teeth. If it's more of a chatter skip, it could be a simple derailleur adjustment.
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Re: Chain strangeness

Postby drifte » Wed Nov 28, 2012 2:16 pm

Sprockets appear ok to me. Also wasnt an issue before the new chain? Is it possible its the wrong length? Its more of a CLUNK, and I can actually continue with forward momentum. I'll take a pic of the sprockets and see what you all think.

Thanks
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Re: Chain strangeness

Postby NoyzSource » Wed Nov 28, 2012 5:31 pm

I'm not an expert but derailleur alignment would be my starting point. I wouldn't rule out just having a bad (although new) chain. Maybe one of the links was just built wrong and is sticking/twisting when it is under load. Wrong size chain meant for 8spd rear vs 9spd? Chain link with a bent side causing the tooth to "miss" the link opening?

I wouldn't think chain tension (long chain) would be a problem because the tension on the top of the chain is whatever force you put into the pedal. Lots of slapping on the bottom of the chain would cause rear derailleur problems or chain suck if the chain were too long. At this point I am flat out talking out of my a$$ on subjects I know very little about (like online communities and engaging online users).

Another idea off the top of my head (or out my a$$) is that maybe the front gears were not put on correctly. Slightly out of parallel (wobbly) or not tight (wiggly)?
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Re: Chain strangeness

Postby Farmboy » Thu Nov 29, 2012 11:21 am

Before you had the chain replaced, how much did you ride? Miles? Years?
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Re: Chain strangeness

Postby urbanbigfoot » Fri Nov 30, 2012 8:21 pm

All this talk has me thinking...maybe we need to do a shop night at someones home soon. I often work on my bikes alone, but I have to admit, it's nice to have a beer w/ like minded individuals, especially ones who I can learn a thing or two from. That said...I've seen this issue because of a small nick in a single chain link, making the link sticky as it passes through the rear derailleur. It might be a new chain, but entirely possible that the link is grooved or nicked. Just saying...

So, who's in for a shop night? I can't ride much, so I might as well tune the $hit out of my bikes.
When I was a kid, I rode bikes. Now I ride bikes and act like a kid. Some things never change.
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Re: Chain strangeness

Postby drifte » Sat Dec 01, 2012 3:59 pm

As the temperature goes down and the ski resorts open up my attention strays to snowboarding. However I spent the morning cleaning the bike, and put in a new tube after the last ride at Sugar Bottom. And snapped a pic of the rear sprockets.
Image

These sprockets have been in use since 2008. Hard to say the amount of use really. The chain doesnt even really look new, Im beginning to question what they did at all? I know they replaced the bearings in the crank as those had play. I wonder if that has anything to do with it.

I had Scheels do this tune up right before I did a cyclocross in DesMoines a few weekends ago. And as I was killing time waiting for the race I noticed a lot of grease and gunk on the sprockets and de-railer. That was my first hint they may not have actually fixed anything...So I'm a bit worried where my $120 went.
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Re: Chain strangeness

Postby drifte » Sat Dec 01, 2012 4:04 pm

Also forgot to mention, I noticed the chain coming off more often now too. It really never would come off before at all. Now its at least once per ride. Heres a pic of the front sprocket..sort of.

Image
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Re: Chain strangeness

Postby crrimson » Sun Dec 02, 2012 1:23 pm

The first thing that jumped into mind for me was an article regarding chain suck, that mentioned problems with putting a new chain on a heavily worn cassette. The problem you describe isn't chain suck though, but I could see where it's possible a new chain could cause issues.

Don't read the entire thing, just see the pictures that shows 'worn teeth, new chain' to get an idea of what the worn teeth look like. To me your rear cassette teeth look OK, but I'm not an expert on it.
http://fagan.co.za/Bikes/Csuck/

Like Greenfast said, start troubleshooting by determining if it happens in every gear, or just in the large front gear. Go to a parking lot, shift through all your gears and crank on it. Make note of which gear combinations cause the problem.

I had Scheels do this tune up right before I did a cyclocross in DesMoines a few weekends ago. And as I was killing time waiting for the race I noticed a lot of grease and gunk on the sprockets and de-railer. That was my first hint they may not have actually fixed anything...So I'm a bit worried where my $120 went.


I would call Scheels and ask them exactly what they did, just so you get a better idea. I'm guessing that gunk is probably from the new chain, they are usually coated in the stickiest gummy grease I've ever seen. I like to get that junk off, clean them right away and re-lube them, so they don't collect so much dirt.

And about the chain length.. new chains are extremely long, is it possible Scheels didn't adjust the chain length when they replaced it? Did you put the bash guard on yourself, and shorten the chain when you put it on? Without a large front ring, you can usually take quite a bit off.

I could see the extra slack the derailleur is taking up is causing it to sit differently & act differently. Another thing you could mess with is the "B adjust screw" on the derailleur, just to see if it has any effect.

http://www.parktool.com/blog/repair-hel ... derailleur

Use the process of elimination, closely observe the chain while pedaling slowly & see if you notice anything out of line, any skipping, etc & post back what you find out. If you need a diff. front chain ring to try to eliminate that as a test I'm sure someone on here would have a middle ring you could try. I have a large one if you want to try that.
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Re: Chain strangeness

Postby Stumpy » Sun Dec 02, 2012 6:55 pm

Chain suck. he he
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Re: Chain strangeness

Postby Farmboy » Sun Dec 02, 2012 8:12 pm

Is the chain coming off on the back or the front? Also, that appears to be an 8 spd cassette. Did they put a 9 spd chain on there?
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Re: Chain strangeness

Postby Rev. Jimmy » Wed Dec 12, 2012 4:02 pm

I think you're just gonna need a new bike.
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Re: Chain strangeness

Postby sbergus » Thu Dec 13, 2012 10:38 am

Rev. Jimmy wrote:I think you're just gonna need a new bike.

Maybe two, you can never be too safe in situations like this.
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Re: Chain strangeness

Postby Byke Dood » Fri Dec 14, 2012 1:31 am

A few of the problems I have had for chain skip are a bent chain ring ,a tight link in the chain , worn out chain rings and a dirty drivetrain


A few thing I have tried for chain drop are keep the chain short as possible , check chain rings for straightness, install newer style rear derailleur with stronger spring.
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Re: Chain strangeness

Postby sbergus » Fri Dec 14, 2012 10:30 am

Byke Dood wrote:A few of the problems I have had for chain skip are a bent chain ring ,a tight link in the chain , worn out chain rings and a dirty drivetrain


I don't think it would be a tight link, when I had a crappy link, my chain would skip on every pass, not just when under load.
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