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"POP" slippage in chain drive train...SOLVED!

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  • Tommycat
    commented on 's reply
    " If I understood it to be as new as what you say I don't know if I would have suggested that to be honest though! =] "
    A fortunate omission on my part! :-)

    "Make sure your chain doesn't have any sticky links."

    Nice catch there sir!
    Verified and then lubricated, all is well.

  • commuter ebikes
    Good info above. Admitting that I am sometimes a lazy "remove and replace" troubleshooter, I would have switched out the freewheel with a brand spanking new freewheel (perhaps even a different brand).

    If that did not fix the problem, I would switch out the chain with a new, slightly shorter chain. And then add a link or two to see if this fixes the problem.

    If that didn't work, I would substitute in a new derailleur. Note that this would force you to set up the new derailleur, which may solve the problem (although probably not).

    This may not be the fastest or most elegant way to isolate the problem, but freewheels, chains and derailleurs are cheap and you are going to need a spare someday anyway. Also, the time spent removing and installing the parts will further strengthen your bike mechanic skills.

    Note that I always substitute in only one "known to be functioning" component at a time, and I definitely throw away the part that was found to be the problem.

    This method of troubleshooting has saved me a lot of frustration countless times. I keep spare parts on hand ready to do it again if necessary.
    Last edited by commuter ebikes; 03-27-2018, 07:21 PM.

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  • calfee20
    commented on 's reply
    Make sure your chain doesn't have any sticky links.

  • AZguy
    commented on 's reply
    When I first encountered the skating it took me a while to sort it out. I adjusted and adjusted, cleaned, lubed........ Just kept getting worse. Replaced the cassette and the problem was solved.

    Since BBSHD'ing over 3kmi I've replaced about five of my top gear cog (11t) and two of the next to top gear (13t).

    What I've experienced...

    Once there is even just one "POP" and it has always gotten worse quickly - within several hours becomes unusable.
    It's very difficult to see the difference between worn one with no issues and one with issues.
    A poorly aligned chain / cassette can cause a relatively new one to start on the way to unhealth. I had a rear hub get loose and allow for a couple of mm's of slop for the cassette and at the end of the ride I needed to replace an almost new top gear. At least they are very low cost!

    As always, YMMV. If I understood it to be as new as what you say I don't know if I would have suggested that to be honest though! =]

    OTOH freewheel cogsets are very cheap and replacing with a wider range unit would certainly not hurt and you might like it...

  • Tommycat
    So taking AZguy's bet, I went in the direction of skating. Since my bike has less than 10 miles on it, with probably less than 1 under human power... :-P I hadn't seriously considered it.
    But after taking and analyzing the video below, it looks clear that skipping is an issue. You can see at the 13 second mark where the idler gear pulls back and just releases. Hard to see full speed, but if you go frame by frame it's very obvious. (Note bike is upside down) Just as would be expected if the chain rode up and over the cogs for a split second.
    Thank you AZguy for your input!

    So how so bad, so quick? Looking closely at the troubled cog it looks pretty beat up. And even closer I can see where the spacer between it and the next cog had some paint wore off due to the spacer being not even all around. Having one side too close to the teeth. Meaning that it would lift the chain slightly on the higher part, making it easier for the chain to slip. And once slipping, all down hill from there...
    Bad stamped part perhaps?

    So on to getting a new threaded freewheel. Getting myself up to speed on how match front chain ring, chain, and rear freewheel as I see you just can't mix and match willy-nilly...

    Anyone think that the spacing between the teeth is excessively wide? EDIT: On looking at replacement freewheels, it appears to be normal.

    In the mean time, I'll try a little more tension as per MoneyPit's suggestion. Thank you.


    Last edited by Tommycat; 03-27-2018, 12:46 PM. Reason: See "EDIT"

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  • MoneyPit
    I have seen this happen on an 11T cog on a mid drive bike and the solution was to pull a couple of links off the chain. I had originally sized my chain generously for a 12T small cog and when I went to an 11T there wasn't enough tension being put on by the derailleur. Solved the problem. Permanently so far.

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  • AZguy
    commented on 's reply
    I understand that. It happens quickly on my mid-drive (~400mi) but I've still ended up replacing a freewheel on my radrover hub drive (~2000mi) *and* my non-electric MTB in years past...

    According to my LBS owner beer associate it's common enough on the non e-bikes to get skating in the top gear cog. Not enough teeth for the chain tension even if it's just you standing on the pedals hard...

    What he describes is exactly how I would describe it when I get top gear skating...

  • calfee20
    commented on 's reply
    He has a magic Pie.

  • AZguy
    My bet is that you are getting skating on the top gear cog - this is where the chain skips (skates) over the top of the cog teeth.

    It looks like your is 14t. At best you've got 6 or 7 teeth in contact with the chain and in the gear where the torque and linear tension on the chain is at the greatest.

    I've had this happen with rear hubs and non-electrics but it take a lot longer since it's all leg causing it.

    I've got an 11t top gear and a 13t next to top. For me, the 11t will start skating at about 400-500mi, the 13t maybe a bit less than twice that.

    My experience is that once this starts it will accelerate very rapidly. It's difficult but not impossible to see the difference with the skating cogs and a new one - it's subtle.

    I'm fortunate that the 11t and 13t cogs are available independently. Then again my cassette is $65-$75 depending on the low gear. This looks like a simple 7sp freewheel and they are very inexpensive.

    Even if I'm wrong, I'd shotgun the freewheel cogset just because it's so cheap and I'd get one with better overall range than that one anyway...
    Last edited by AZguy; 03-26-2018, 04:48 PM. Reason: Get rid of possibly confusing BBSHD comment

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  • Tommycat
    started a topic "POP" slippage in chain drive train...SOLVED!

    "POP" slippage in chain drive train...SOLVED!

    Good day everyone!

    I'm having a problem with my e-bike builds mechanical power train. Here are the details.

    In the highest gear, smallest sprocket, furthest away from the Magic Pie 5 hub motor. And under moderate to strong peddle input I will get what is best described as a "POP" and a quick 10 degree slippage down. Some times twice in quick succession. It happens on either leg driving the force. It seems to me that its coming from the rear freewheel/derailleur. But impossible for me to spot. No problems in any other gear. It's a 7 gear Shimano threaded on freewheel. Single chain ring in front. Twist shifter.

    Efforts to fix...

    Derailleur hanger alignment. Parallel with the freewheel gears.
    Derailleur adjustment, low, high, linear tracking.
    Removal and disassembly of the freewheel hub assembly. Checking of the pawls, ratchets, shimming and general operation and relube. A slight touch of marine grade grease, and 20 weight non-detergent oil.
    Maximum/minimum derailleur gear positions...outside of recommendations.

    I can get everything to work smooth as silk, with perfect alignment, and shifting top to bottom. But the minute I put a bit of power into the downstroke...POP. Arrrggggg.

    In the interest of full disclosure, I seemed to have made it worse after the hub teardown and re-lube...

    Pictures of the terror...

    Inside of the freewheel hub...

    Any help would be greatly appreciated!

    Best regards,

    Last edited by Tommycat; 04-10-2018, 06:29 AM. Reason: Changed to SOLVED...