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Shimano cassette structural bolts sheared from 50A

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    Shimano cassette structural bolts sheared from 50A

    Heads up to anyone thinking of using a Shimano Hyperglide HG20-7.. I had this fail without half dozen rides using a 50A mid drive @52v.



    Closeup of the three bolts inside the cassette:




    The smallest sprocket snapped cleanly in two as well, not sure which happened first (of course someone was borrowing the bike at the time so I'll never know the whole story)

    So....anyone know of a better rear cassette for high power? Clearly one that's just held together by three little bolts is not the best choice.

    #2
    Thanks for posting this. it's very important we share accurate info so we can all find the best possible solutions...

    Comment


      #3
      What size chainring were you using? Do you remember what cog you were in when it failed? Do you shift under power?

      I am currently using a very similar (cheap) Shimano 8 speed cassette with the Cyclone 3000 (Luna 60 volt battery) with no problems so far. (500 miles). But the apparent cheap quality of Shimano 8 speed cassettes and derailleurs does not inspire confidence. The reason I am trying this is to gain the benefits of the strength of the 8 speed Wipperman connex chain.

      Comment


      • paxtana
        paxtana commented
        Editing a comment
        42t chainring. The rider was lugging it instead of keeping in the correct gear for his low speed. I am replacing with a 9spd Shimano HG400 and just using low limit derailer screw to keep it out of the extra gears. Looks better built.

      #4
      The carnage begins....Good for you, finding a limit! And for sharing your cool toys.

      Funny, how sharing toys uncovers new issues...happens to me, too.
      Fabrication is fun! Build something today. Show someone. Let them help. Inspire and share. Spread the desire.

      Comment


        #5
        At 50 x 52v, I think I'm done with derailers.

        3spd IGH or bomb-proof single speed is my new mantra.

        Thanks for sharing!
        Last edited by BikeEV; 11-21-2016, 05:49 PM.

        Comment


          #6
          Just completed a build using a BBSHD, 72volt batt and a controller from ERT. Can snap chains at will! Was cruising at 33mph, a speed that the stock BBSHD is out of breath, and this thing makes enough power to snap a chain (10 speed) under brisk acceleration. The cassette will not last long. I am already seeing a SA 3speed in the future! It's either that or a Rohloff! And a nice hefty KMC single speed chain!

          Comment


            #7
            I been very happy with the cassette I replaced with but if it ever happens again I think I will go with the sturmey archer rx-rk5.
            Designed for heavy duty applications, but has more gear range than the nexus 3.

            Comment


            • Rix Ryds
              Rix Ryds commented
              Editing a comment
              More gear range true, but not nearly as robust. Might not be happy with 3000 watts! Search the forum for and read Spinning Magnets article on IGH's. Very good and accurate info there!

            #8
            This post made me very nervous when I saw it on Oct. 2, because I have been running a very similar cassette (Shimano CS-HG31 Altus 8 Speed Cassette) on my Cyclone 3000 since March. I am running the Cyclone at over 3000 watts as measured by a CA3 Bus and have had no problems with the cassette.

            Comment


              #9
              Originally posted by Sather View Post
              This post made me very nervous when I saw it on Oct. 2, because I have been running a very similar cassette (Shimano CS-HG31 Altus 8 Speed Cassette) on my Cyclone 3000 since March. I am running the Cyclone at over 3000 watts as measured by a CA3 Bus and have had no problems with the cassette.
              It probably helps that you know better than to be lugging the motor, unlike my brother who was riding it at the time. ended up going with a Shimano Hg 400 to replace it. No problems since, it is still a Shimano but clearly is using higher-quality metal, at least it does not look like dingy gray. Apparently this model in particular has a fairly high number of ebike users that say it's a good choice







              Click image for larger version

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                #10
                Nice job buddy! I am a big fan of the all steel shimano cassettes with very little material removed. I'm running a shimano 10 Speed HG50.
                https://www.amazon.com/Shimano-CS-HG...cassette+steel

                Takes big power no problem, the 11T cog will wear out if you use it too often, but it can be replaced individually.

                I'm also a fan of KMC chains.

                Comment


                • paxtana
                  paxtana commented
                  Editing a comment
                  Oh hey man good to see you here! Yeah I love KMC chains. Also KMC missing links which some cool guy clued me in on ;)

                #11
                It probably helps that you know better than to be lugging the motor, unlike my brother who was riding it at the time.
                What RPM (pedal cadence) range do you aim for?

                Comment


                  #12
                  Thanks for all the useful info on this thread. Looking to upgrade my BBSHD to 72v 40-50 amp in the future. A couple of questions. At 72v do you really need 7-10 gears. What crank gear have you been using? There is limited info out there on the 72v BBSHD. ERT stated he used a 30T. Are there 5 speed cassettes that are more heavy duty, that could take a bigger chain?

                  Comment


                    #13
                    3kW will be quite abusive to any bicycle cassette gears/chain. Hell, my mechanical instincts tell me 1-1.5kW is bad enough.

                    3 widely spaced gears do the trick for my BBS02. Sacrificing a few gear ratios for a better chain line is well worth the minor tradeoff.

                    I use cheap steel cassettes without rivets/spider so they can be stacked in any combination desired.

                    Here’s a picture of one of my cassettes arranged for 3 wide ratios - 14-32T tugged by 44T chain ring. Derailleur limits adjusted to only those 3 middle gears and moved the shift cable to the LH formerly front shifter. Plenty gear range, IMO.

                    Click image for larger version

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                      #14
                      Got it thanks for clue . seems like the right thing to do.

                      Comment

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