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BBSHD crank arms: How heavy duty are they?

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    #16
    Idealy, the crank arms would be splined and not square tapered. Splined arms do not need to be torqued. They should be also forged for durability.

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      #17
      The common "square taper" crank arms need to be very firmly torqued down. They use a steel bolt pulling the aluminum crank arm onto a steel spindle, so you can really tighten it down very hard with very little danger of stripping the threads (use proper torque). If the crank arm has even the tiniest amount of looseness in it, the aluminum will get deformed, and at that point, no amount of tightening will fix it.

      Square-taper was a reasonable choice for the BBS02, but I personally believe the BBSHD should have had the ISIS splined interface (common on off-roaders), and also a 40A controller. Even 35A would have been significant. it should also have the option of bluetooth between the controller and the dashboard, so it could have fewer wires...

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      • JAFO
        JAFO commented
        Editing a comment
        Isn't the BBSHD programmable to 40 amps?

      #18
      Square is "Old School"... But if you use quality alloy ones, whichever length you choose for your riding style, and keep them tight, they will last thousands of miles.
      I destroyed 3 Bafang crank arms in a few months.
      I've NEVER destroyed a quality branded arm.

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        #19
        Road bikes (racing bikes) also have splined bb spindles and crank arms nowadays. Shimano has its own spline type and other makes have their own. So there is not many new square tapered bb spindles now. A square taper bb could still be adequate but the crank arms then HAVE to be forged. Otherwise, the arms will just get stretched at the interface with the bb and also at the pedal interface. So I guess, we will be looking to address this situation with after market parts.

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          #20
          Reading about weak crank arms has affected the way I ride. When standing on the pedals over bumps, I try to keep my feet high/low, with crank arms vertical, instead of horizontal. It's not as nice that way, but the loading of the square taper interface is much less. So, less abusive. Standing on the pedals while they are horizontal is much more severe for crank arms, due to the longer moment arm for the applied force.

          So, that's one more thing we can do to help make them last.
          Fabrication is fun! Build something today. Show someone. Let them help. Inspire and share. Spread the desire.

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            #21
            Originally posted by spinningmagnets View Post
            The common "square taper" crank arms need to be very firmly torqued down. They use a steel bolt pulling the aluminum crank arm onto a steel spindle, so you can really tighten it down very hard with very little danger of stripping the threads (use proper torque). If the crank arm has even the tiniest amount of looseness in it, the aluminum will get deformed, and at that point, no amount of tightening will fix it.

            Square-taper was a reasonable choice for the BBS02, but I personally believe the BBSHD should have had the ISIS splined interface (common on off-roaders), and also a 40A controller. Even 35A would have been significant. it should also have the option of bluetooth between the controller and the dashboard, so it could have fewer wires...
            If Bluetooth works like every other I've seen on bikes, I'll keep the wires. But I do agree in theory. As far as crank arms, I guess it's luck and a 1/2 drive breaker bar.

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              #22
              People mentioning really torqueing the bolts down, but I haven't seen a specific torque value mentioned. I found some other post that stated 25-27 lbs. I found at that setting I need to re torque them every few rides. Since I'm still trying different pedals I haven't used lock-tite.
              I found this ebay ad for forged ebike crank arms,
              http://www.ebay.com/itm/262368812076...%3AMEBIDX%3AIT
              The problem I'm having is my ankle hits the side of the crank arm, so I bought a pair of these to try. I bought a left&right 5/8"-24 tap and 9/16" crank inserts to re-thread the left crank to a right hand thread.
              http://stores.ebay.com/wheelandsproc...race+crank+arm
              I also ran across an ad selling a Scram square hole crank arm, must be vintage, I couldn't find any more info.
              I also bought one of the Luna right offset arms. It's a few ounces heavier than the left. I drilled 4 9/16" holes to lighten it up. The quality of the aluminum looks o.k., nothing bad.

              Comment


                #23
                these look amazing, lighter and stronger. for bbshd
                http://lekkie.bike/product/buzz-bars-straight/
                and bbs01/02
                http://lekkie.bike/product/buzz-bars-offset/

                Comment


                • paxtana
                  paxtana commented
                  Editing a comment
                  We will have those in stock next month, just got the new Lekkie Bling Ring sizes in stock but for some reason the cranks are coming later.

                #24
                Why not try unicycle crank arms? $30 a pair for steel and they will never flex. Who cares about the weight, you have already added 25+ lbs in battery and motor, at least the weight is down about as low as you can get. For the weight weenies who still think they own a bicycle the cranks also come in alloy for a bit more money.

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                  #25
                  152mm, 170mm, and 175mm cranks can be purchased overseas at Eunorau Ebike Online store for $25..00/pr. ( Aliexpress) You may have to search "bbshd" which will bring up a number of vendors, than search for this particular store.

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                    #26
                    Shimano FC-E6000 Crank Arm

                    Thats all you need. 22 eur / pair in EU. https://www.bike24.com/ sends in USA but too expensive postage. I am sure you can find them in USA.

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                      #27
                      These are getting good reviews from ebikers
                      https://www.amazon.com/dp/B002I7K5XA...oding=UTF8&me=

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                        #28
                        I'm grounded at the 45 mile mark because the right pedal stripped out the crank arm. It's marked 8fun. I wish I could order the Amazon prime unicycle ones but they are back ordered. I was going to use the left arm off another bike but the square hole is 45 degrees out of phase.

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                        • max_volt
                          max_volt commented
                          Editing a comment
                          I will fess up and admit I slapped the bike together and did the noob act of putting them on the wrong sides. DOH

                        #29
                        WOw I am so Happy my bike had square taper to begin with now. I may just skip the Bafang arms when my kit comes in. Whenever that will be since its been 2 weeks and no tracking number yet,

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                          #30
                          these are black and have an offset
                          Everybody should be biking is our motto. If you need bike parts to get back on the road, give us a call or order online.

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                          • max_volt
                            max_volt commented
                            Editing a comment
                            I killed these too by not checking mounting bolt tightness.
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