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Waxed chain skips at high power

Hi!
Is it normal for a waxed chain to skip at high power?
A few months ago I switched from oil to wax because I was tired of the dirt oil attracted. I replaced both chain and cassette when doing that, but only a few rides later it started skipping.
FACTS:
* Time trial bike
* 11 speed Shimano
* 56 Osymetric chainring
* 11-23 cassette
* Starts skipping around 800 watts (so sprinting is impossible)
* Did not seem to do that at the very beginning when I changed everything
* Chain couldn't be shorter (on 56/23 the derailleur spring is having a hard time)
* Di2 Short cage - Should I consider some special cage or spring? If so what?
* I rewaxed once
* Los Angeles beach weather

Posts

  • sungodsungod Posts: 13,526
    shouldn't cause skipping

    you say "after a few rides", perhaps the chain starts binding due to loss of lubrication, the chainring shape may exacerbate things

    what matters is total distance, distance before rewax will depend on the wax/method/conditions etc., 200-300km seems typical

    fwiw with the original ufo drip wax and riding at high temperatures 30-40c i needed to top-up after any long ride (only takes a few minutes)

    if you're using a hot dip wax it'll go further but it takes longer to rewax, one option is fit a connex link and have 3-4 chains to use in rotation, once a chain has done the distance, put it back in the wax and fit a freshly rewaxed one
    my bike - faster than god's and twice as shiny
  • PMarkPMark Posts: 65
    When did you last change your front chain rings? I had this issue after changing my chain/cassette and thought I might have broken something when fitting. But it was just my small front chainring was too worn.
  • Thanks for the reply SunGod.
    My guess was that skipping could be caused by some wax built up at the wrong place, like between the teeth on the cassette and outside on the chain. But here you're saying it could also be the lack of effective lubrication of the chain itself? The chain becoming less flexible rather than the contact surfaces becoming too slippery?
    What do you mean by "top-up" ? Soak the chain again quickly? But isn't that a "rewax" then?
    I have to admit I made a custom wax with these:
    https://www.amazon.com/dp/B07M627HZ2 (453g)
    https://www.amazon.com/dp/B084VNXNMK (45g)
    https://www.amazon.com/dp/B07TJ5J717 (a tiny bit, like 1g)

    markdurdle:
    Hmm... Never changed it and I have to admit my riding is very aggressive and I only use the large chainring (Osymetric 56), I almost never shift the front. I do shift the rear a lot to find the ideal cadence at all times.
    But if this was the case, shouldn't that also have happened when I was using oil? (I cleaned it up when I switched to wax).
    Also, it would take a slow-mo camera to be 100% sure but it seems to me that it is the rear that skips.
  • MattFalleMattFalle Posts: 4,102
    have you tried a different chain and/or cassette to see if it skips then?
  • MattFalle: By different you mean same specs but just a new one again? That's a good idea, I might buy a new cassette and new chain just to make an elimination-testing that way. I'll always use it later anyway so it's not wasted.
  • PMarkPMark Posts: 65

    Thanks for the reply SunGod.
    My guess was that skipping could be caused by some wax built up at the wrong place, like between the teeth on the cassette and outside on the chain. But here you're saying it could also be the lack of effective lubrication of the chain itself? The chain becoming less flexible rather than the contact surfaces becoming too slippery?
    What do you mean by "top-up" ? Soak the chain again quickly? But isn't that a "rewax" then?
    I have to admit I made a custom wax with these:
    https://www.amazon.com/dp/B07M627HZ2 (453g)
    https://www.amazon.com/dp/B084VNXNMK (45g)
    https://www.amazon.com/dp/B07TJ5J717 (a tiny bit, like 1g)

    markdurdle:
    Hmm... Never changed it and I have to admit my riding is very aggressive and I only use the large chainring (Osymetric 56), I almost never shift the front. I do shift the rear a lot to find the ideal cadence at all times.
    But if this was the case, shouldn't that also have happened when I was using oil? (I cleaned it up when I switched to wax).
    Also, it would take a slow-mo camera to be 100% sure but it seems to me that it is the rear that skips.

    An easy way to rule out the front chainring is to find a hill and just use the small chainring and see if you can get the chain to jump.
  • MattFalleMattFalle Posts: 4,102

    MattFalle: By different you mean same specs but just a new one again? That's a good idea, I might buy a new cassette and new chain just to make an elimination-testing that way. I'll always use it later anyway so it's not wasted.

    yup and yup - as ypu say, if it all works fine, dump the old stuff. if you still have a problem then you know its the chainring.

    job's a fish.
  • Thanks both, I didn't think about that, indeed. I will try to throw a lot of power in a hill first, even though we could argue that the angle of the chain may affect the skipping, but probably negligible, it will be a good first indicator, especially if it keeps happening.
  • MattFalleMattFalle Posts: 4,102
    either way, keep us all updated dude.
  • banditvicbanditvic Posts: 525
    Have had the same problem on a few bikes i have had in after fitting a new chain, usually the front large chainring worn.
  • nibnob21nibnob21 Posts: 207
    Only time I've had a waxed chain skipping it was the cassette. Seeing as you've replaced that and the chain, process of elimination would suggest the chain ring.

    But as has been suggested already, no harm in buying a few new bits if they'll be needed in the future anyway.
  • sungodsungod Posts: 13,526

    Thanks for the reply SunGod.
    ...
    But here you're saying it could also be the lack of effective lubrication of the chain itself? The chain becoming less flexible rather than the contact surfaces becoming too slippery?
    What do you mean by "top-up" ? Soak the chain again quickly? But isn't that a "rewax" then?
    ...

    yeah, one test is take off the chain and see if there're any links that aren't as free moving, riding in hot dry dusty conditions if the chain develops a squeak it's another sign that it has gone dry

    with the drip waxes you can leave the chain on the bike - that's why i say top-up - adding to what is already there - it also flushes out some of the dust, i add a drop per link and then leave it overnight to seep in and let the solvent evaporate

    with hot wax, i.e. what you have, it will probably run further before needing a re-wax, but then you need to remove the chain and put it back in the molten wax for a while, the wax needs to get inside the rollers - this is why i suggest fitting a connex/similar link and having a few chains to use in rotation, so that you will always have a fresh chain ready when you need it

    as others said, chainring wear is another thing to check, a worn ring can cause 'chain suck' - the chain doesn't disengage cleanly from the bottom of the chainring, instead it gets dragged up, it's not a good feeling when it happens, worst case something can break
    my bike - faster than god's and twice as shiny
  • bikeradar0597828571@bador.net[email protected] Posts: 13
    edited 17 May
    So I thought I would give an update.
    I wanted to just change the chainring without even trying anything else because it was the thing that made most sense to me by elimination, but I was waiting on Osymetric to get back in stock with their 56 tooth aero.
    So conclusion: YES it was the chainring indeed.
    With the new one I can put as much power as I want and it holds really well. In fact even the shifting (rear shifting surprisingly) feels a lot faster and more committed.
    Since I knew what a rear skipping feels like I really thought that was I felt was that, but a front skipping (which I didn't know was even possible with a 56 chainring) actually feels exactly the same as a rear one.
    Photos attached of before/after chainrings.



    Actually the photos are too low resolution once uploaded here. So here are the originals: https://florianbador.com/pub/20210516-chainrings/
    PS: gosh... in the picture "20210516_173504.jpg" on the top right it's really obvious. Some of the teeth in the old one are completely triangular while they're round in the new one.
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