Chain degreasing and skipping on smallest cog

Marais

New Member
Region
Europe
Hello all,

I repeat for those who did not see my first post that I ride a 2020 Giant Entour +

I often have problems in the highest (8th gear) on my bike of the chain skipping a groove in the cog.

This DOES NOT happen on any of the other 7 gears.

I have replaced the cassette = twice, and even the chainring twice also. The chain many times.

When all is replaced, it works for a few weeks and then inevitably starts up again.

Every bike mechanic I've seen says I wear the little gear sprocket often by pushing too hard.

I have had the derailleur set many times by professionals, not really any better.

I also grease the chain regularly, have tried two different kinds of grease.

That being said, last month I thoroughly degreased and cleaned my chain and the cassette and the problem went away, again only for a few weeks.

It's a bit frustrating to ride in 7th gear when I can in 8th.

Anyone out there with the same experience or suggestions?
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are you starting in that cog? are you spinning? if you work too hard in that cog instead of spinning you will wear it out faster. but even then you should get a few thousand out of it. on our bosch powered tandem we would cruise in the 9th cog and it would skip around 2000 miles.
 
The derailleur itself may have also lost tension which will be most obvious in the smallest cog. The Altus derailleurs are dirt cheap so maybe consider replacing this and having it properly aligned at the time of fitting. That chain also looks a little loose - largest cog would see the derailleur in the circa 5 o’clock position. I would try removing 2 links.
 
are you starting in that cog? are you spinning? if you work too hard in that cog instead of spinning you will wear it out faster. but even then you should get a few thousand out of it. on our bosch powered tandem we would cruise in the 9th cog and it would skip around 2000 miles.
In fact, from the beginning, I've been very careful to always to start in gear one or sometimes gear two or three. Never in the 8th of course!
 
The derailleur itself may have also lost tension which will be most obvious in the smallest cog. The Altus derailleurs are dirt cheap so maybe consider replacing this and having it properly aligned at the time of fitting. That chain also looks a little loose - largest cog would see the derailleur in the circa 5 o’clock position. I would try removing 2 links.
I know the chain is a little loose. But I've replaced it three times. Also as I mentioned the cassette. Each time it works for about a month. Each time the Giant mechanics mention that I'm wearing the smallest cog down by forcing. On the other hand I like going fast. Maybe it is time to change bikes?
 
get a seven speed freewheel with the same high gear( if possible) or a larger front chain ring with a 7 spd rear sprocket sounds like there is a bit of a serious misalingment,some of these low count cogs are pretty puny. just excuse me if you have a cassette,btw are you running a middrive motor?
 
The derailleur itself may have also lost tension which will be most obvious in the smallest cog. The Altus derailleurs are dirt cheap so maybe consider replacing this and having it properly aligned at the time of fitting. That chain also looks a little loose - largest cog would see the derailleur in the circa 5 o’clock position. I would try removing 2 links.
I agree with Juggernaut, your derailleur should be at 5 o'clock while on the largest cog. That might help if your chain were tighter.
 
Things to check:
-Make sure chain is short enough that the derailleur is still tensioning it when on the smallest cog. Shift to the small-small combo and feel how much tension the chain has, then shift to a middle combo and compare.
-Check for tight links. Sometimes things can kick up and hit the chain, and occasionally that will dent a link and you'll get one link that doesn't rotate freely. The smallest cog is where the chain makes its tightest wrap so a tight link may cause skipping. Go through the chain one link at a time and make sure they all rotate freely.
-The usual alignments. Hanger is square to the wheel, limit screw is properly adjusted, shifter cable tension is adjusted so things line up.

Other possible problems could be that you're just using the small cog more than the others. It has the fewest teeth so will wear the quickest (chain forces are distributed through fewer teeth so they just wear faster). If you stay in the small cog a lot (especially on an ebike where drivetrain forces are higher) you may want to change to a larger chainring, which will move your gear range up and let you use more of the cassette.
 
get a seven speed freewheel with the same high gear( if possible) or a larger front chain ring with a 7 spd rear sprocket sounds like there is a bit of a serious misalingment,some of these low count cogs are pretty puny. just excuse me if you have a cassette,btw are you running a middrive motor?
I'm American but have lived in France for 40 years. The gears in the back = cassette or something else in English? (I googled it but not sure???) Yamaha Giant Syncdrive.
 
Things to check:
-Make sure chain is short enough that the derailleur is still tensioning it when on the smallest cog. Shift to the small-small combo and feel how much tension the chain has, then shift to a middle combo and compare.
-Check for tight links. Sometimes things can kick up and hit the chain, and occasionally that will dent a link and you'll get one link that doesn't rotate freely. The smallest cog is where the chain makes its tightest wrap so a tight link may cause skipping. Go through the chain one link at a time and make sure they all rotate freely.
-The usual alignments. Hanger is square to the wheel, limit screw is properly adjusted, shifter cable tension is adjusted so things line up.

Other possible problems could be that you're just using the small cog more than the others. It has the fewest teeth so will wear the quickest (chain forces are distributed through fewer teeth so they just wear faster). If you stay in the small cog a lot (especially on an ebike where drivetrain forces are higher) you may want to change to a larger chainring, which will move your gear range up and let you use more of the cassette.
Indeed. I replace the chain quite often and have since that old photo. But even the "new" chain is getting loose and yes the 8th gear's teeth are getting worn. I hate to ride in 7 when I can in 8 it is just a little slower. I'm going to try to degrease the chain soon to see if it is going to help. I have my usual "gig" in July so I'm going to wait a month to get Giant to revise all = new cassette, new chain, get the derailer correct (I'll try your suggestions this week for the alinement in the interim), and maybe the plateau. Also brake pads and maybe a purge?

The gig =


Pics from last year =
 

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A bent derailleur hanger and nothing else. Unless you are often wearing out your smallest cassette cog.
Riding in the highest assistance and in the smallest cog all the time?
 
A bent derailleur hanger and nothing else. Unless you are often wearing out your smallest cassette cog.
Riding in the highest assistance and in the smallest cog all the time?
I agree with this assessment. Bent derailleurs can be a hard thing to check without the proper tool, though.
 
My first cassette lasted about 2 weeks before the skipping started! My second cassette has been running over 2 years now and still works and feels fine.

I don't have my magic formula, but with the advice given already, I can't really stress enough how important it is to wear in your components and allow them to marry up properly. Ride it gently for the first few weeks, get 200-300 miles on it before you up the power and you'll be rewarded for it.
 
Measuring the chain stretch is vital.
Once the stretch has gone past 0.5%, the chain should be replaced, as it would make the small cassette cogs wearing at an alarming rate.
Many people just kill their chains and cassette cogs by constantly riding their mid-drives at an excessive assistance power.
 
Hanger has to be pretty bent before it causes consistent issues, but its an easy thing for a shop to check and fix. I do suspect the chain is a bit long, based on the one picture that was posted (which had the chain in the large cog in back and the derailleur wasn't highly tensioned as I'd expect). But it does really just sound like they are running high assist and primarily riding in the highest gear, which is going to cause a ton of wear on that cog. Small cogs (on normal bikes) aren't usually used in a high-power way, they are to maintain at higher speeds. The chain is only engaging a few teeth on an 11t cog so big mid-drive power through that is going to wear it fast.

The long-term solution is to increase front chainring size so you're using more of the cassette at usual riding speeds (assuming you are willing to move your effective gear range up and lose a little low range). From what I see, the Entour came with a 12-32 cassette and 38t chainring, which gives a max gear-inch of 88 with 700c 40mm tires. Actually pretty low for a bike primarily ridden on pavement. Going to a 44t chainring would effectively move gearing 2-3 cogs up the cassette from where it is now.
 
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