Chain "vibrates" on higher gears

Question

My freewheel that I have installed myself only 1.5 years ago has totally worn out by the moment and so I just had it replaced along with a chain at the workshop. I'm still concerned though about the previous one's extremely short lifespan and thus suspicious about my current setup as well.

It's 7 gears freewheel on a folding bike (no front derailleur), and the problem is that it's feels very smooth on 4th gear. When you switch on higher gear up to the 7th, you start to feel some strange vibration as you pedal, which, I suppose, may indicate that the chain is not properly aligned and will wear the cogs out quickly.

Am I just being paranoid? Apart from that, everything seems fine now - gear switching is smooth and under load they don't switch lower with a distinctive noise, as before with my old freewheel. Should I try to play with cable's tension to get rid of that vibration on the higher gears as I use them more often than lower ones?

Thanks.

Daniel R Hicks · Accepted Answer

"Vibration" could indicate a bad chain angle or a misadjusted derailer.  On the other hand, it's typical to have smoothest operation near the middle of the cluster and some very slight noise/vibration higher and lower.  Hard to say whether you have a problem or not without knowing the precise nature and severity of what you're experiencing.

Note that a chain will last roughly 2000mi or 3000km (+/- 50%).  After that it's sufficiently worn that it's beginning to cause excessive wear on the sprockets.  A rear cluster will last roughly 5000mi/8000km under normal use but will wear faster if a worn chain is being used.  Also, if you're on your third cluster your front chainring is likely fairly worn, though the condition of a single front ring is usually not a major issue.

mikes · Answer

Is it possible that part of the folding mechanism is not aligned well resulting in frame flex under the heavier loads of the highest gears

user3641272 · Answer

I could try to explain it but it's probably best if you read into Chordal Action (Chordal Effect) in chain driven systems - here's a link: chain-guide.com. Simply put, the effect is more noticeable in small toothed sprockets tahn it is in larger ones.

Answered by user3641272 on September 20, 2020

Purr · Answer

There is typically more feed back on smaller gears, it is impossible for me to tell whether your vibration falls within this typical increased feedback.

In your case I would play with the H screw first and foremost, especially if there is a significant and sudden increase in feedback between 6th and 7th gear.

In my experience it has been all of the following at various times, those marked with a * do not apply to your setup:

Only the smallest gear excessive vibration/feedback:

Rear derailleur needed adjustment on limit screw to allow it to go
far enough 
AND in another case to stop it going too far. 
*Front derailleur needed adjustment to stop chain rubbing. 
Frame protector needed to be moved forward as it was interfering with lowest gear.

Multiple lower gears excessive vibration/feedback:

Rear derailleur needed adjustment, typically the limit screw also needed adjustment, but not always.
*Rear derailleur was not indexed correctly (for indexed types only)
Chain/cassette too worn/too much difference in level of wear.

Regarding the life of your freewheel/cassette: 1.5 years is a meaningless measure in biking but seems pretty good without further information to go on. Distance, riding style, riding conditions, maintenance, and attention to chain wear + chain replacement will all play a significant role in lifespan. For example: I've destroyed an SLX cassette (and chain) in 3 months and been quite happy with the lifespan, when considering all the factors that resulted in this "short" life span.

julaen · Answer

Chordal action. Look it up, i have the same problem.

Chain "vibrates" on higher gears

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