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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.

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    Google 'chordal effect' - it's a known issue with small cogs - I have it too – user3641272 Feb 26 '15 at 8:39
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"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.

  • When I had my chainset replaced last time, I had to adjust the front derailer after using the knob near the shifter on the handlebars. The chain was rubbing on the derailer when I used the harder gears. – ananka Feb 4 '12 at 19:38
  • Of course, the OP's bike has no front derailer, but a slightly misadjusted rear derailer can produce a similar symptom. And for bikes with a front derailer there's often a way get a "fine adjustment" from the front shifter, to adjust for chain rub. – Daniel R Hicks Feb 4 '12 at 22:24
  • Last year I have travelled roughly 5300 km on my bike (I know because almost every ride is recorded with GPS). That makes sense then, it was too much for my poor chain. Thank you! – Yuriy Feb 5 '12 at 7:06
  • I had a grinding sound caused by the chain (when on the smallest sprocket) rubbing against the special nut which takes the bolt that secures the derailleur hanger (lugnut-mounted style) into the dropout. The nut is thin, round disc, with a thicker tongue part on one side which mates into the dropout. But with the wide freewheel I was using, which provides a small cog (11 tooth), the chain was coming into contact with the disc, causing rumbling. The fix was to file it down the disc a little bit, focusing on the edge that was catching the chain. – Kaz Aug 19 '14 at 23:48
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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

  • It's not the case, the folding mechanism is fine and holds the frame in place firmly. The bottom bracket, is a bit loose so it wobbles a little bit when pedalling but as I can judge that doesn't change chain's angle that much. – Yuriy Feb 5 '12 at 8:54
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    @Yuriy your loose bottom bracket will make a huge difference. If you can wobble it with just your hands then it's going to be all over the place under normal pedalling loads. – Phil Willoughby Jun 22 '14 at 18:33
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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:

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

Multiple lower gears excessive vibration/feedback:

  1. Rear derailleur needed adjustment, typically the limit screw also needed adjustment, but not always.
  2. *Rear derailleur was not indexed correctly (for indexed types only)
  3. 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.

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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.

  • Can you expand on your summary? We really don't like answers that link off to other websites because they tend to vanish from the web over time. More information in your synopsis will improve this answer. Also have a browse of the Tour which is found in the Help menu, to learn how SE varies from the regular-old web forum. – Criggie Dec 9 '16 at 20:13

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