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Loose Chain

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Old 08-16-18, 07:38 PM
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BirdsBikeBinocs
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Loose Chain

The chain on my Schwinn GTX-3 is loose. Is there a way to tighten it up some.?? Does the rear derailure (spellcheck) need an adjustment.?? Mind you, it's not coming off, it's just full of slack and I'm noticing a slight clunk in my pedal stroke. Any help on this.??
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Old 08-16-18, 07:43 PM
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Maybe the chain is too long and needs to be shortened?
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Old 08-16-18, 07:59 PM
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is this a new condition? was any maintenance done recently? is the rear axle fully in the dropout?
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Old 08-16-18, 08:04 PM
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My best guesses:

- Slack in chain due to RD spring broken or shifted out of position.

- Clunk when pedaling:
a) Pedal bearing worn out or in need of adjustment.
b) Bottom Bracket bearing worn out.
c) If these are plastic-bodied pedals, then the plastic may have stretched out, allowing bearing to slide around.
I've experienced all 3.
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Old 08-16-18, 08:06 PM
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A derailure equipped bike will have a chain tension that is set by the rear der cage spring. When the top length of the chain is under little/no tension it will bounce up and down due to gravity and that the cage spring is a spring. The smaller the cog or ring in use the greater chance the chain will strike the chain stay.

So to the OP- please rediscribe your concerns. When does the bike "clunk"? Are you pedaling, how hard, in what cog/ring combo? What you might be referencing could be very normal or indicate a growing issue with indirectly related parts (like the BB). Andy
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Old 08-16-18, 09:09 PM
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Originally Posted by Andrew R Stewart View Post
A derailure equipped bike will have a chain tension that is set by the rear der cage spring. When the top length of the chain is under little/no tension it will bounce up and down due to gravity and that the cage spring is a spring. The smaller the cog or ring in use the greater chance the chain will strike the chain stay.

So to the OP- please rediscribe your concerns. When does the bike "clunk"? Are you pedaling, how hard, in what cog/ring combo? What you might be referencing could be very normal or indicate a growing issue with indirectly related parts (like the BB). Andy
I'm not familiar with all of your terms. The bike has probably 250 to 300 miles on it and I've made no adjustments other than the brakes. Rim brakes.

The clunk doesn't always happen. The clunk happens when I'm pedaling in a fairly "stiff" gear, up to speed and maintaining speed. It's in the middle ring up front and a smallish ring out back. Honestly, the bike runs quite nice. I'm riding more and more so I was just looking things over and found a loose chain.

I turned the pedals by hand and noticed it was the slack chain giving the clunk right when I wind up the pedals by hand, right at the start. And, it's happened since new. Frankly the issue has gotten better. When it was new I noticed it more than I do now. I think I could take out a link or 2. I don't want to, I'm just guessing it would bring the chain back to near normal if I did.

I'm wondering if I found the chain to be loose because of the gear it's in. 21 being the highest gear, meaning a fast gear, the bike is in about 8th gear as it sits when I inspected it. I honestly have no complaints, it just seemed quite loose and where as I am riding more, I want it to be as efficient as I can make it.

Not sure I've helped myself, or the replies I'll get. Ask more questions if need be, I'll try to have an explanation for ya. It's a $300 bike. Altus (shimano) deralleur.
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Old 08-16-18, 09:28 PM
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How loose is it?
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Old 08-16-18, 09:30 PM
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Originally Posted by BirdsBikeBinocs View Post
I turned the pedals by hand and noticed it was the slack chain giving the clunk right when I wind up the pedals by hand, right at the start. And, it's happened since new. Frankly the issue has gotten better. When it was new I noticed it more than I do now. I think I could take out a link or 2. I don't want to, I'm just guessing it would bring the chain back to near normal if I did.
OK, I once had that symptom;
It was a loose lockring on the cassette.
To diagnose it, grab the cassette by the gear teeth, and try to make it wobble.
If it wobbles, the wheel needs to be removed, the lock ring tightened to spec (probably 30 ft-lbs), then the wheel is reinstalled.
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Old 08-16-18, 09:51 PM
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3B- Sorry if my terms are unfamiliar, I am an old guy. I really wonder if your clunk is a crank/BB thing. Of course it could be more then one thing going on too

"I turned the pedals by hand and noticed it was the slack chain giving the clunk right when I wind up the pedals by hand, right at the start." This could be the ratchet mechanism engaging with the first slight crank/pedal movement. But we can't try this ourselves so...

The chain needs to be long enough to allow the largest rear cog and front ring to be used at the same time. Any less chain length then this "big/big" combo will bend or otherwise damage the rear der and/or drop out. Also this chain likely has peened over pin ends (rivetted) so will want proper reassembly to be safe. KMC makes a range of connecting links to help with this. It is uncommon these days to have a bike come new with a too long chain. Why? because in about another 55 bikes the maker will have a free chain if they save one link (being a pair) per bike. Money talks loud.

What front and rear cog/ring combo did you test the chain in? The small rear cog and small front ring will always have the slackest chain tension and really shouldn't be ridden in for any length of time for best efficiency. The more the chain crossing the greater the chain friction. Andy
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Old 08-17-18, 12:01 PM
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Originally Posted by Andrew R Stewart View Post
3B- Sorry if my terms are unfamiliar, I am an old guy. I really wonder if your clunk is a crank/BB thing. Of course it could be more then one thing going on too

"I turned the pedals by hand and noticed it was the slack chain giving the clunk right when I wind up the pedals by hand, right at the start." This could be the ratchet mechanism engaging with the first slight crank/pedal movement. But we can't try this ourselves so...

The chain needs to be long enough to allow the largest rear cog and front ring to be used at the same time. Any less chain length then this "big/big" combo will bend or otherwise damage the rear der and/or drop out. Also this chain likely has peened over pin ends (rivetted) so will want proper reassembly to be safe. KMC makes a range of connecting links to help with this. It is uncommon these days to have a bike come new with a too long chain. Why? because in about another 55 bikes the maker will have a free chain if they save one link (being a pair) per bike. Money talks loud.

What front and rear cog/ring combo did you test the chain in? The small rear cog and small front ring will always have the slackest chain tension and really shouldn't be ridden in for any length of time for best efficiency. The more the chain crossing the greater the chain friction. Andy
Oh. Okay. So when I'm up to speed always use the larger ring up front. Okay, that makes sense. I've often wondered about that. Seems I'm always trying to look down and back to see which ring I'm actually on. And each time I look I'm reminded... I can't see the rear sprocket. lol. I am using the big ring on the front more and more.
If the rain holds off I'm going to ride later on. I need to take more mental notes.

I like this bike a lot. I've made some fit changes and the bike is feeling better and better as I fine tune it. It's a fun bike to ride being a hybrid. Shifting is smooth as can be. That said, I'm headed towards a road bike for next spring.

Can you tell me what the BB is.?? I can't figure that one out. Thanks for your time. And it's okay to use terms I don't know. It's a learning exercise for me.
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Old 08-17-18, 01:32 PM
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BB--Bottom Bracket. Where the pedal axle goes thru the frame.
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Old 08-17-18, 02:10 PM
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I'd recommend developing a relationship with a local bike shop, or maybe there's a bike coop in your area. A direct observation of your symptoms by a knowledgeable person should get you quickly on the right track.
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Old 08-18-18, 07:44 PM
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OP here to report back.

I rode about 10 miles in the past 2 days. Bike is running good however, the rear gear sprocket has a bit of slop to it. Someone suggested to grab it and see if it wiggles. It does. I would say at the most I can move it about an 1/16th of an inch, or less. I'm not overly concerned about it but I do realize it will most likely get worse.

If I take the rear wheel off can I get to a part that needs to be tightened.?? Special tool needed.??

I also checked the chain while it was in a different gear. It wasn't as loose as when it was in an easier gear. I feel as though I'm getting an efficient stroke on the pedals. I cleaned the cog(gear wheels) and I'm not noticing that clunk in the pedal stroke as often as I once did. It did happen once today when I was up to speed. It could be that my leg gets lazy in the middle of the pedal stroke.?? I actually think it goes back to the loose chain. I just don't know.

Checking in with a bike shop is a good tip. Duh on me.
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Old 08-18-18, 07:59 PM
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Sprockets shouldn’t move at all. You’ll likely need a specific tool to tighten it, so you could invest in one ($5-10), but you’ll need a torque wrench also to do it right, so maybe take it to the bike shop
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Old 08-18-18, 08:01 PM
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250 miles or so. New bike? if so it does, as all new bikes do after several hundred miles, need to be looked at by someone that knows how to check and adjust all the components and inspect spokes, wheels and such. The shops I'm familiar with all tell the new customers to bring their bikes back for a free checkup. Many think this is just to get you back in the shop, but it's not the over riding reason. New bikes or new components, cables or wheels just sometimes need some attention after their initial break in period.
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Old 08-18-18, 08:10 PM
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How about some photos of the bike showing the issues so we won't all just be guessing.
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Old 08-18-18, 08:33 PM
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Originally Posted by CliffordK View Post
How about some photos of the bike showing the issues so we won't all just be guessing.
In all due respect, I'm not sure what a photo would do for you in this instance. I have a little play in the back sprocket. And, I'm saying my chain is on the loose side of average. Other than that, I love the bike. Goes over the road quite nicely for a hybrid. One click equals one gear. Shifting is smooth. Pedal stroke is smooth too other than an occasional "clunk" 2 or 3 times on a 5 or 6 mile ride.

Those are the facts. What would you want a picture of.??
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Old 08-18-18, 08:45 PM
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Well, you say a loose chain. But, a lot would be visible by looking at the chain. Hanging slack? Rear derailleur when the bike is shifted into the big ring up front and the big sprocket behind. Also the rear derailleur when shifted to the small ring up front and the small sprocket behind.

A clunking feeling might also be due to a sticking freewheel or freehub. That might be difficult to photograph... But you could backpedal and see if you get more slack in the upper part of the chain. Also being slightly out of gear, or badly cross-chained can cause that same slack feeling.
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