I saw my bicycle chain very dirty so after many months since last time I cleaned it and I checked the general state of the drivetrain. I totally forgot that a couple of years ago the chain was already somewhat stretched.

I found what looks like a very worn out chainring, a very stretched chain and a cassette in a mixed state.

Chain is 1.8% elongated.


still dirty

Cassette: it looks like the 2nd sprocket is the most worn out, the 1st, 3rd and 4th not so much. It is a Maillard Helicomatic so I cannot easily find new sprockets, and probably not new in any case. I may need to replace the whole wheel. I wonder when this bicycle has been manufactured...

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Which parts is good idea to replace now, given the actual status?

  • It depends on what you can afford. If broke, then change gears to avoid skip! With some cash, get the new chain. Lots of cash, you could weigh the cost of a cassette against a bike upgrade. In any case, a cleanup is the first step.
    – rleir
    Apr 24, 2017 at 0:11

2 Answers 2


Wow I just noticed that does not look like a serviceable chain ring. I think you need a new crank. I don't have time right now but you need to adjust my answer. Depending on the cost of the crank try and cycle one more cassette with the current.

Changing the chain is the cheapest thing you can do. As the chain wears it cause more wear on cassette and chain ring.

I typically get 3 chains per cassette and 2 cassette per chain ring. But you have single chain ring so 1 cassette per chain ring?

You have let the chain get to a point you need to replace everything. The cassette does not look that bad but based on chain stretch it is likely worn out.

You are going to think this is strange but at this point you have nothing left to lose. Every mile you get out of what you have is another mile. I advise you to buy 1 chain ring, 1 cassette, and 3 chains with master links. This is the part you are going to think is strange. If your current chain has a master link (looks like it does) then try a new chain on what you have. If it does not jump then ride it. If it does jump then clean up the old chain and put it back on. Ride until it jumps (misses). I even save chain 1 and 2 that were replaced at 0.75% and give the best one a try. Once it is totally trashed then replace it all.

There is narrow wide chain ring now but I don't think it goes down to 8 speed. Not sure if you would be better off with a 9 speed narrow wide.

Looks like you use the big gears on the cassette very little so consider a smaller chainring (crank?). And that might be a freewheel.

  • 1
    Riding the transmission "into the ground" is a valid plan, then replace the lot when it no-longer functions properly.
    – Criggie
    Apr 23, 2017 at 22:07
  • I think this idea is good. I'll try a new chain and see how it goes. This especially because I will need a new wheel together with the cassette, since Helicomatics are not manufactured anymore.
    – FarO
    Apr 24, 2017 at 13:48
  • One gear skips with the new chain.
    – FarO
    Apr 26, 2017 at 12:45
  • @OlafM Don't use that gear?
    – paparazzo
    Apr 26, 2017 at 13:03
  • If it's the only one to skip, it means it was the most used gear... It's the 15 teeth sprocket: gear-calculator.com/… I can either put the old chain back, but then by the time it skips or breaks, the chainring will be gone as well, or replace now wheel, cassette and chain to preserve the chainring (probably a better idea).
    – FarO
    Apr 26, 2017 at 16:52

That chain should have been changed ages ago - at or before 0.75% ideally. At 1% you will need a new cassette. To get to 1.8% is astounding, and means that the cassette and chain have worn into each other,

The chainrings look OK, because there's a lot more teeth engaged compared to the cassette, however if the chain slips at the front after replacing chain and cassette, then the chainring needs doing too.

You might also want to examine your two jockey wheels and consider replacing them. The main difference of that is improved shifting and little to do with skipping, but given the rest is that worn you may as well change all the wear items.

Keep your chain cleaner too - that's a contributing factor on transmission wear.

If I were you, I'd give the bike a proper refresh.

  • New brake and shift cables, inners and outers
  • New brake pads front and rear
  • New bartape

Depending on wear you might even consider new tyres and saddle, but they're more expensive so not a priority item.

Give your bike a proper clean and degrease (that means using an old toothbrush. While doing so, examine the frame for cracks and any damage that was hiding under the dirt and oil.

  • 1
    Nice answer but this is an 8 speed Acera. It is getting into a range where you don't want to invest more than you have to.
    – paparazzo
    Apr 23, 2017 at 21:20
  • 4
    @Paparazzi If the bike fits its worth fixing. I ride a 3x7 speed RSX. A worn cassette and chain are normal consumables. Agreed, a chainring is a bit pricy and I'd think twice before replacing one.
    – Criggie
    Apr 23, 2017 at 22:01
  • 1
    It had an older gear shifting mechanism, I replaced it myself two years ago because the original one had a bent/rebent in position/loose derailleur. Still, I want to save the bike because it is nice looking with brazed joints :) Also, as pointed out, we are talking about replacing consumables...
    – FarO
    Apr 24, 2017 at 13:16
  • 1
    I will give the bike a refresh as you suggested, also by taking it apart completely to clean everything real nice and grease the bearings again (that means front wheel and steering since I don't have the tool to remove the helicomatic cassete). Still, given that I have nothing to lose, the other answer suggesting to wear cassette and chainring completely out is probably better in my case.
    – FarO
    Apr 24, 2017 at 13:50

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