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

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    "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,

    T.C.
    Last edited by Tommycat; 04-10-2018, 06:29 AM. Reason: Changed to SOLVED...
    See my completed Magic Pie V5 rear hub motor E-Bike build HERE.

    #2
    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

    Comment


    • calfee20
      calfee20 commented
      Editing a comment
      He has a magic Pie.

    • AZguy
      AZguy commented
      Editing a comment
      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...

    #3
    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.

    Comment


      #4
      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.




      Regards,

      T.C.
      Last edited by Tommycat; 03-27-2018, 12:46 PM. Reason: See "EDIT"
      See my completed Magic Pie V5 rear hub motor E-Bike build HERE.

      Comment


      • AZguy
        AZguy commented
        Editing a comment
        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...

      • calfee20
        calfee20 commented
        Editing a comment
        Make sure your chain doesn't have any sticky links.

      • Tommycat
        Tommycat commented
        Editing a comment
        " 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.

      #5
      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.

      Comment


        #6
        Originally posted by commuter ebikes View Post

        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.
        Well said, and good advice. I call it the rifle verses shotgun approach... ;-)

        OTOH freewheel cogsets are very cheap and replacing with a wider range unit would certainly not hurt and you might like it...
        Along this thought... I feel that I could use a higher gear on the top end. As I like to at least keep cadence with the motor. :-) But that would mean a smaller back-end cog, which with the skipping hazard I'm more than a little reluctant to do...Would it be a plausible idea to mount a EDIT: LARGER chain ring in front, say on the outboard side of the existing one and then not use it.(the existing one) As I think just to replace would be difficult. And stay with a replacement freewheel with the same cog sizes? Another benefit would be that it would shift the chain to the right more, closer to the small cog end in back. Less linear offset.

        Your opinions please...
        Last edited by Tommycat; 03-28-2018, 08:09 AM. Reason: See EDIT: had the size backward....
        See my completed Magic Pie V5 rear hub motor E-Bike build HERE.

        Comment


        • AZguy
          AZguy commented
          Editing a comment
          Maybe better is to go for a larger chain ring and a wider range cogset - go for the set with the very largest first gear you can get then scale the chain ring to keep the low end and buying yourself the top.

          OTOH depending on your driveline components - i.e. you aren't using a $600 EX-1 or something, get a cogset with the widest range, top and bottom and if you chew up the top cog.... replace the cogset, even my expensive M8000 cassette is ~$70 and that doesn't break the bank. A quick search shows 7sp 11-34t cassettes for $14!!!

        #7
        Originally posted by Tommycat View Post

        Well said, and good advice. I call it the rifle verses shotgun approach... ;-)



        Along this thought... I feel that I could use a higher gear on the top end. As I like to at least keep cadence with the motor. :-) But that would mean a smaller back-end cog, which with the skipping hazard I'm more than a little reluctant to do...Would it be a plausible idea to mount a smaller chain ring in front, say on the outboard side of the existing one and then not use it.(the existing one) As I think just to replace would be difficult. And stay with a replacement freewheel with the same cog sizes? Another benefit would be that it would shift the chain to the right more, closer to the small cog end in back. Less linear offset.

        Your opinions please...
        I bought a couple of these for my hub bikes. http://lunacycle.com/parts/bicycle-p...ing-crank-set/

        Click image for larger version

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        This requires a different bottom bracket and may require you to rework your PAS sensor. I am still fighting with mine. It is a good thing I have another bike to ride.

        Comment


        • MoneyPit
          MoneyPit commented
          Editing a comment
          I have a couple of these, although I bought mine off of AliExpress and they are all black vs. the ones Luna sells. They are almost the cheapest cranksets you can buy but for hub motors where you don't have to put full stress on the drivetrain, they work great. Mine were still going strong at 4k miles before I swapped in a set with 175mm crankarms.

          calfee20 what are you fighting on them? They are fairly straightforward 130 BCD cranks and I use the same PAS sensor disk you are showing in that pic. I did change out the chainrings/guard on both of mine.

        • calfee20
          calfee20 commented
          Editing a comment
          The explanation is kind of long so I attached it to my build thread to maintain the continuity of that thread.

          https://electricbike.com/forum/forum...ctra-fat/page2

        #8
        Originally posted by calfee20 View Post


        This requires a different bottom bracket and may require you to rework your PAS sensor.
        That's what I was afraid of...so will probably stay away from that. And don't have PAS...but looked into it and see it can be used on my pie. Will save that for another thread. :-)



        So with all the good input this is where I stand...

        What I know... It's definitely slippage! Slippage is probably caused by worn gears, worn chain, not enough teeth engaged, or loose chain tension and typical derailleur alignment.
        So I decided to try to get rid of the problem first, before investing in parts.

        This is where I started...with the original set-up, and good adjustments. Note the engagement of teeth with the idler gear quite high off the cog, 6 or less teeth engaged...







        Still slipping... So went to the bungee tool box and grabbed and installed a tensioning tool to bring the idler down to engage more teeth...




        Still slipping...hummmm but not as much! So with teeth engagement taken care of...added another tensioning adjuster to tighten up the chain a bit...





        And that did the trick! Absolutely no slipping issue, so it can be done! So with renewed faith that it can be over come even with a worn cog and chain. I'm planning my next attack.
        As there doesn't appear to be any other adjustments.Thinking that rotating the D-hanger counter clockwise to get the assembly as close to the torque arm (and teeth) as possible to grab as many teeth as possible.
        And removing a couple links to increase chain tension.
        Always mindful of course that it must be able to spool up to the low gear cogs just as well, without the idler gear hitting the cogs.
        Can it be done?



        See my completed Magic Pie V5 rear hub motor E-Bike build HERE.

        Comment


          #9
          I solved my slippage buying new chain and casette they were visually worn.
          After that, under load I had clicking noise coming from the casette and derailleur. I solved it by tightening my mech hanger screws(they shook themselves loose) and tightening the rear wheel.
          When you put a big load on the drivetrain the wheel might flex to the side the chain is pulling on it, to an extent that the chain will be willing to go onto the next cog. So have your dropouts tight. The symptom of ruined hub bearings is the same, so it is worth checking first as it is a lot cheaper.
          Last edited by Tommm; 03-30-2018, 06:05 PM.

          Comment


          • Tommycat
            Tommycat commented
            Editing a comment
            Axle nuts torqued to 50 foot pounds, with jam nut backers. Custom torque arms on both sides...check.

          #10
          FYI I usually have to add and remove links in order to establish the proper chain tension when I install a different size freewheel. This after faithfully following the proper method for sizing a chain.

          Also, I usually have to add and remove links for the same reason when I set up a derailleur.

          The sweet spot is always a chain with just about 1" of vertical play, but I sure have to add and remove many links before I get it to shift properly.

          I use SRAM chains with Powerlinks so it is very easy to add and remove links with the use of Park Tool MLP-1.2 Masterlink pliers.
          Last edited by commuter ebikes; 03-30-2018, 09:24 PM.

          Comment


            #11
            With new parts in hand... well O.K. A new master link, but there are 5 in the bag. ;-) I started the final push!


            Please refer to this picture for actions taken...





            #1 First action taken... verify correct chain length. Using the largest chain ring to largest cog and add 2 pins method. Found that my chain was 2 links too long--- corrected.




            Results... no change.

            #2 Notched the derailleur hanger around the axle to allow it to rotate counter-clockwise. Letting the gear pulley to get closer to the cogs. See top picture item #3 and the next picture.





            Results... no change.

            #4 Gear pulley still looked to be riding too high off the cog. So it was either decrease spring tension at the hanger pivot, or increase spring tension at the #4 pivot point.

            As the chain was still a bit slack, I increased the spring tension at #4 pivot. Now not having any adjustment options this was done by drilling out a new spring attachment point in the end housing to make it a quarter turn tighter.





            Results... Torque arm was interfering a bit. So had to go to #5...

            #5 Removed a quarter inch of material off the torque arm to eliminate interference with derailleur gear operation.

            Results...Pay dirt! Absolutely no popping, skipping, skating, or slippage at the cog, whats so ever! Even under the most aggressive power stroke I can muster. :-P

            Here is a shot of the changes made...





            You can see the better chain angle engaging more cog teeth, and with better chain tension, all is well.

            Did the change from a 10mm round axle to a 14mm flat on 2 sides axle cause the issue? Which changed the over all position of the derailleur gears? Bad cog spacer? Extra mass of the back wheel?
            Cheap/// errr inexpensive donor bike (parts)? We'll see if this lasts... Now for that ****** squealing front caliper brake! LOL.

            Thanks to all for your input!

            One happy cat,
            T.C.








            Last edited by Tommycat; 04-10-2018, 06:26 AM. Reason: ...spelling
            See my completed Magic Pie V5 rear hub motor E-Bike build HERE.

            Comment


              #12
              [QUOTE=Now for that ****** squealing front caliper brake! LOL.

              Thanks to all for your input!

              One happy cat,
              T.C.[/QUOTE]

              I have found that if your disc brakes are squealing that replacing one piece rotors with two piece rotors will fix the problem. Here is my disclaimer. I have only ever had 2 bikes with disc brakes but changing to Shimano 2 piece rotors stopped all squealing on both bikes.

              Comment


              • AZguy
                AZguy commented
                Editing a comment
                My experience with brake squeal has suggested a lot of "normal" squeal has to do with the pad material and bedding in. If the pads are new and sintered metal (vs. organic) then I'd give them time - my experience has been the sintered pads are very prone to squeal when new....

                Contaminated pads might be more prone to squeal too... As always a flush with brake cleaner doesn't hurt but a badly contaminated set (like a leaky cylinder that's been oozing brake fluid into the pads over a long time) might just need to be replaced...

              #13
              What AZGuy said. You need to bed in bike brakes just like you do high performance/track auto brakes. Its an identical procedure.

              On cars, with respect to track / racing brakes, squeal and dust is a function of the pads not being 'up to temp' meaning they are meant to be used hotter than they are able to get in normal street use. Conversely, running street brakes on track, they stay nice and quiet but after a few laps you look at the pads and they have been worn way down. I have seen brand new supposedly hi perf street pads wear down to the steel backing plates in a single day running laps on a race track.

              Moral of the story: Match your brake pads to your use. If they are squealing look for a more 'comfort' oriented kind of pad and see if that makes the problem go away. Don't go to race type hi-po pads unless you are trying to solve a known deficiency in stopping power that just pads can help you solve. As far as pad material goes, you get either quiet pads that don't stop so great or loud dusty pads that grip the bejesus out of the rotors. In an ideal world you find a compromise you like.

              Copying a post I made on another forum:

              ... Bedding brakes is something most people don't do in the automotive world and nobody does in the cycling world. You need to do it. Magura's recommendation is to go to a reasonably brisk speed and brake down to a crawl - never a stop! - and speed back up and repeat the cycle 20 times. I don't think they were thinking about the speeds ebikes can accomplish, nor their weight, so I checked at 15 and the front rotor was uniformly blue-black and smoking ... as it should be. Job done. Now turn around and go home without using the brake you were bedding AT ALL to let it cool. Do NOT stop along the way. You want the rotor to cool gently without the caliper sitting over one spot for any amount of time (stopping will cause uneven cooling where the caliper is sitting and warp the rotor). Do NOT use the brake you just bedded. Use the other one (and by extension, do not bed both brakes at once). It only takes about a mile of slow (PAS1) cruising back to cool that rotor off just fine.
              In this pic taken after I got back home from bedding the front brake, the now cooled rotor was nowhere near as black as it was when I ceased the bedding process. Within a few days there was no sign it had ever happened.

              Click image for larger version  Name:	20170415_112904_1280.jpg Views:	1 Size:	274.6 KB ID:	61721

              Comment


                #14
                And now that we've successfully hijacked a chain thread into a brake thread... A quick "just my take" on pads...

                For long hard braking like a long downhill the best choice is likely a pad with an aluminum backing since the aluminum is better at shedding heat - particularly after letting up a bit (or completely).

                For short very hard braking a steel backing may be better since they take longer to heat up just like they take longer to shed it.

                Organic pads are generally a lot less sensitive to bedding than metal pads and typically are much quieter, particularly when not fully bedded - metal brakes can make a ton of noise when they aren't.

                Metal pads last a *lot* longer.

                Metal pads are usually only bonded to steel plates so aluminum is not generally available.


                So if you hardly brake at all, want inexpensive pads that typically won't make noise and bed on their own or at least much more quickly then organic on steel.

                If you are a downhill guy then organic on aluminum is likely the way to go but buy an extra set - they just as likely won't last long.

                If you approach corners hot, bleeding a lot of speed quickly before entering turn, or any other use case where there's lot's of very hard slowing, the metal pads on steel are likely the best way to go (this is how I ride and what I run). Just remember if you want to go through turns fast you need to scrub most of the speed before you are doing much turning allowing for any suspension, tires, etc to settle in to a less dynamic state well before the apex. The old moto racer mantra "you can't enter a turn too slow nor leave it too fast!" is good to keep in mind until it's autonomous... and I'm foolish enough at my age and handicap to fall back on my old moto ways.... =]

                Comment


                  #15
                  Pulling back sharply on the rod to set the hook... lol. Next issue coming up! But let's get on the right track here. Doesn't anybody read my bike build blog? :-P

                  Anyway, let's meet over HERE!
                  See my completed Magic Pie V5 rear hub motor E-Bike build HERE.

                  Comment

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