# Bottom Bracket roughness or vibration and other questions



## T1Callahan (Jan 28, 2020)

I recently purchased a 54' Schwinn Hornet, and as I pedaled it, I am feeling a bit of light vibration or roughness at the bottom stroke of the right pedal.  There is no noise and its very slight, but it is there and noticeable.   Its not every stroke, and when it happens it happens for about 5-10 times around then doesn't happen for 5-10 times.  So I pulled it appart, and appeared to be recently lubed. So I cleaned it, took some photos, and re-packed it and put it back together.  I did notice that one of the cones had some very light grooving, but the cup felt smooth and everything else looked smooth.  It rode was ok for about a minute, then it started again. My guess is the bottom cone and or Cup need replacing. Or maybe I and the person before over tightened?  What are your thoughts? I attached some photos.

If it does need replacing, should I replace the whole set with bearings or could I try just one piece at a time? 
And how do I know Im not buying another bad set? 
Also want to make sure Im buying the right thing, what should I look for? 
Last question, when I put it back together, what is your recommendation for tightening? I had finger tightened, then 1 or 2 light taps with the screw driver just a bit beyond that so there is no lateral movement.


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## Autocycleplane (Jan 28, 2020)

Try putting fresh 5/16" balls in your existing retainers and don't over-tighten.


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## SKPC (Jan 28, 2020)

Those look fine to me..Chain?

Edit: Inspect the cleaned ball bearings with a magnifying glass...spin them around and look for any flat or rough spots. It could be the issue. If only ONE is pitted or flatted you will feel it..just takes one.  The cones are clean..imo


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## T1Callahan (Jan 28, 2020)

I can try to replace the balls. They looked pretty good overall but maybe an issue?  The Chain wasn't over tightened by any means and had some play in it- maybe too loose.  Does the slight grooving you see on the one cone seem normal and not a possible symptom to the problem?


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## Cooper S. (Jan 28, 2020)

Is the chainring or cog bent any?


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## T1Callahan (Jan 28, 2020)

Cooper S. said:


> Is the chainring or cog bent any?



I'll check for that tonight. there was nothing obvious when I was cleaning it all, so if it is it would be slight. But I'll definitely scrutinize it tonight.


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## buickmike (Jan 28, 2020)

All that stuff is worn
is


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## T1Callahan (Jan 28, 2020)

I see what your saying BuickMike.   I don't think I realized that the Outside of that cone is on the outside of the bracket and cup and that it could be rubbing as the issue, but you are probably right here. Where would I find the ID of the bottom Bracket, not the crank correct?


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## T1Callahan (Jan 28, 2020)

Cooper S. said:


> Is the chainring or cog bent any?



I check this and the chainring is out somewhere between  1 to 2 mm,  the cog appears to be true.


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## GTs58 (Jan 28, 2020)

I wonder when the last time that chain has been cleaned and checked. That's another thing to consider doing while your have it in the shop for repairs.


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## Saving Tempest (Jan 28, 2020)

That sure sounds familiar...Darla is also a '54 Hornet as well and does much the same thing.


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## Autocycleplane (Jan 29, 2020)

Are sure you just don’t have the chain too tight? Sounds like the “tight spot” in the chain (front sprocket not perfectly round/centered - common) and that can feel like it’s the crankset. If your cranks spin smooth with no binding, etc without the chain then it’s probably something else and not your BB.


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## SKPC (Jan 29, 2020)

THE CHAIN!!  We sometimes forget the most important component in the drive system..the chain...yours looks forlorned and uncleaned or uncared for at best.  Please clean and measure you chains everyone!!  How hard can it be? Measuring one link will do nothing but confuse you.  Measure pin to pin over 12".  If it measures 1/16" to an 1/8" longer than 12", your chain is toast.  See above post by ACP.


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## T1Callahan (Jan 29, 2020)

SKPC said:


> THE CHAIN!!  We sometimes forget the most important component in the drive system..the chain...yours looks forlorned and uncleaned or uncared for at best.  Please clean and measure you chains everyone!!  How hard can it be? Measuring one link will do nothing but confuse you.  Measure pin to pin over 12".  If it measures 1/16" to an 1/8" longer than 12", your chain is toast.  See above post by ACP.



I will definitely work on the chain next.  I hope that is it because a good chain cleaning is much easier than trying to find a decent new cup and cone set.  The chain is dirty but does move freely and doesn’t seem over tight with Roughly 3/4”  of play. But I will work on cleaning it this weekend.


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## T1Callahan (Feb 7, 2020)

Ok, I serviced the chain last weekend and is now looking sharp,  and finally took it out today for a nice ride.  Its definitely not the chain causing the issue. its not terrible, but these things tend to get worse not better. I may try to replace the bearing Balls next as @Autocycleplane suggested.  I will also start looking for a new bottom bracket set, but this may take some time to find a decent set.   Still worried Ill end up getting the wrong ones as the photos on eBay are usually very bad.


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## piercer_99 (Feb 7, 2020)

SKPC said:


> THE CHAIN!!  We sometimes forget the most important component in the drive system..the chain...yours looks forlorned and uncleaned or uncared for at best.  Please clean and measure you chains everyone!!  How hard can it be? Measuring one link will do nothing but confuse you.  Measure pin to pin over 12".  If it measures 1/16" to an 1/8" longer than 12", your chain is toast.  See above post by ACP.





The chain on the right in this photo was making crazy noise.

The chain on the left is a 56 link chain.
The chain on the right is a 55 link chain.   Just a little stretched and playing hell on the chain wheel and cog.


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## SKPC (Feb 7, 2020)

Let's see your right pedal.  Is it or could it be the pedals' cones/races/bearings?  How long did your chain measure pin to pin past the 12" of measurement that it should measure?


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## T1Callahan (Feb 7, 2020)

piercer_99 said:


> The chain on the right in this photo was making crazy noise.
> 
> The chain on the left is a 56 link chain.
> The chain on the right is a 55 link chain.   Just a little stretched and playing hell on the chain wheel and cog




I think I missed this detail about measuring the chain by @SKPC.  So I just measured it, but I have no idea what Im looking for/at.  Should there be a certain number of links in 12 inches?   At 12 inches it doesn't line up. Its right in between and either way long or way short if its supposed to come out even at 12 inches.  If I was to guess what I think you'd say, is that its about 1/8" too long and therefor the chain is stretched.  See the photos of how I measured.


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## SKPC (Feb 7, 2020)

Measure a totally straight section of the chain center of link pin to center of link pin over a 12" distance on your tape?  How much longer does it measure over 12"?
Edit:  It looks stretched about 1/8".  If it was not stretched, it would measure exactly 12"  This stretching can cause the problem.   This causes noises on the sprockets, especially if the chain was run on other sprockets.  But I am not convinced this is the problem.  It may be your pedal.


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## T1Callahan (Feb 7, 2020)

SKPC said:


> Measure a totally straight section of the chain pin to pin. How much longer does it measure over 12"?



This is how I did it.  If your Your looking at the photos above- especially the second photo,  to me it looks 1/8" too long, but this is the first time I'm doing it.  The first photo shows exactly how I lined it up.


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## piercer_99 (Feb 7, 2020)

almost 3/16" of stretch, in a foot, add that up for the entire chain.   Even if it is only an 1/8"  on a four and a half foot chain 54", that is 5/8" of stretch, you will hear some noise from it slopping into the gear teeth.  If it is 3/16" in a foot, then you are pushing 7/8" stretch.

The chain I showed on the right had an inch and 3/8" stretch to it, it growled.


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## SKPC (Feb 7, 2020)

And make sure you re-read post #12 by Autocycleplane on page one.  This could also be the issue.


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## T1Callahan (Feb 7, 2020)

SKPC said:


> And make sure you re-read post #12 by Autocycleplane on page one.  This could also be the issue.



Ok, I loosened it up a bit, and has quite a bit of play in the chain now. Im not an expert but seems a bit too loose, but at least if it was too tight before, its not now.  I took it out around the block tonight and its still there.   
The thing that strikes me is its inconsistency.  Its not always getting this small vibration.  It will do it for say 10-20 cranks then be completely smooth for a bit- then back to the minor vibration.  If I was guessing..it seems like maybe one of the balls has a flat spot or something and rotates just right in the cup to cause then issue, then it rotates out of position and the issue goes away.   
I work in computers, and we troubleshoot issues all the time, but whats making troubleshooting this more difficult is that I don't have other bikes with the same parts, so I can't just pull things out of a known good working bike and replace these parts one at a time to isolate the issue. 

So far we have eliminated the chain being too dirty and not lubed properly, or the chain being overly tight. Also,  the chain ring, although not absolutely true, is only 2 mm out.
   So I guess it could still be the stretched chain, or the bottom bearings or the cones, or maybe the cups?  Anything else I'm missing?


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## GTs58 (Feb 7, 2020)

How are your teeth on the chain rings? Are they hooked, shark toothed or unevenly worn?

Check out Sheldon's page here. https://www.sheldonbrown.com/chain-wear.html

The new, unworn chain links fit the bottom of the gaps between sprocket teeth. Chain tension from pedaling pulls the links so the rollers are trapped behind the hooked teeth. As each roller comes around to the top of the sprocket, the hook pulls it downward (red arrow), then chain tension overcomes this pull. The roller breaks loose, rolling up the back of the hook, so the hook yanks the chain backward slightly with relation to the sprocket. Then the roller pops off and the chain jumps slightly forward. This happens for every roller which comes around, dozens of times per second. *The resulting roughness can be felt through the pedals.* The roughness is worse than with teeth which are only sloped.


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