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Huge Chain injury on eBike with attached picture

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    Huge Chain injury on eBike with attached picture

    Saw this on the Luna Cycle Owners group on FaceBook:

    "Be careful of the folding bike chain guard it can cause this. When the bike and I toppled over on the left side causing my leg to rest on the chain guard somehow the engine engage causing it to spin and the plastic cut my leg like a circular saw. May need plastic surgery."

    See attached. The injury was caused by the motor continuing to run after he fell. The front gear and chain guard tore up his leg badly.

    Anyone know of a chain guard that does not spin with the front gear? This needs to be fixed! I have a KHS-500 and my front gear and chain are totally exposed. I want to cover it, so this can't happen to me.

    Note the guy in picture fell off his bike when moving zero MPH. He just tipped over and he got THIS!

    Any ideas?


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    Attached Files

    #2
    Looks painful. It's a weird set of circumstances. I wonder what chain guard he had on it, I didn't think the Luna folder comes with one?

    The only thing I can think of is an old school style full coverage guard.
    similar to this,
    https://www.amazon.com/Not-applicati...217405&sr=8-26

    Comment


      #3
      How about a motor cutoff if the bike is at angle of say 45-60 degrees from vertical ? Could be as simple a tilt switch in series? or parallel? with the brake switch.

      Comment


        #4
        Thinking about it you could see how tipping over between hitting the ground and or hitting legs could have got enough pedal rotation to engage the assist but once you were down there should not have been any more pedal rotation or enough to make it think you were still pedaling so it should have stopped. That then brings in the question of was there a throttle? I'm gonna guess yes and that was likely why it kept going. Depending on how and what you landed on just about any throttle design could maybe engage.

        Interesting question about some sort of tip over sensor. If that was a thing I would think the Bosch systems would have it. Those seem to be the most popular around the world and Bosh is the company that is really self promoting that they have the safest systems.

        Comment


          #5
          This just seems far too oddball to worry about - at least I'm not... many millions of miles have been put on these things and injuries like this sure don't seem common... seems it would require the throttle to be stuck or active and seems odd for that with a half twist which is what I've got - maybe easier for a thumb throttle or full twist?

          Kill switch would be silly easy to integrate into a BBsxx - just put a momentary button in line with the P+/PL on the display cable..

          Comment


            #6
            Half twist I suppose would be the least likely since that leaves a fairly small area that has to get a pretty specific motion to activate. Full twist could easily activate from the end or the right contact over a fairly large area. Thumbs are a small target but if you hit em fairly easy to operate.

            Comment


              #7
              Falling is bad, period... no matter the speed... gravity wins... there are always dangers when you fall, this is one but seems like one with only a very remote possibility... proper risk management is about assessing the consequences, the probability of the occurrence and potential mitigation costs

              Hard to see an easy mitigation beyond the kill switch and potentially the throttle itself... trying to cover the chain and ring isn't terribly practical on many of our bikes - not that it can't be done but what a mess... while these consequences are harsh they are probably unlikely to be life altering beyond a bad scar... I guess you never know tho...

              Maybe I have a jaded perspective on scars...

              Pain is temporary
              Bones heal
              Glory is forever
              Chicks dig scars


              Just kidding - hope the guy heals up well... I know too well how badly things can go...

              Comment


                #8
                Originally posted by 73Eldo View Post
                Half twist I suppose would be the least likely since that leaves a fairly small area that has to get a pretty specific motion to activate. Full twist could easily activate from the end or the right contact over a fairly large area. Thumbs are a small target but if you hit em fairly easy to operate.
                Agree with you on the half-grip twist throttle if one is wanting a twist throttle. Even people used to full-grip twist throttles on motorcycles can have a learning curve with how twitchy twist ebike throttles can be. By "twitchy" I don't necessarily mean that the power doesn't come on smoothly. I mean that they are usually responsive enough that just an accidental rub by the hand or something else can cause the bike to get away or at least be an annoyance. I'm a motorcycle guy used to a life long throttle exposure, but motorcycles as a general rule have a clutch when they're in gear, and nothing happens until you let the clutch out even if you have the throttle pegged wide open...LOL! Most ebike throttles are more like having automatic transmissions in vehicles with the selector in drive...ready to go at the touch of the accelerator pedal. This is a good thing, but not when the throttle gets bumped, grabbed, or hit accidentally.

                At this point I've tried the Bafang universal push forward thumb throttle, the Bafang side push thumb throttle (like an ATV), the full-grip twist throttle, and the half-grip twist throttle. For mountain biking in technical terrain the universal forward push thumb throttle was safest as it's more out of the way where I had it mounted on the left handlebar side. However, it wasn't as intuitive to use for a motorcycle guy like me. The full-grip twist throttle ended up being too touchy occasionally, even brushed by branches or when I'm wrestling with the bike dismounted in a precarious position.

                The half-grip twist throttle has turned out best for me as it still has the twist grip throttle function but without all the exposed "live throttle" to the end of the bar. I even cut the half-grip down a little as I felt it was too long for my preference. Mine is now more the size of something like a Grip Shift shifter toward the inside of the bar. Cutting down the half-grip was easy as there are no electrical components on the end. This setup can still be bumped or accidentally grabbed/twisted in a hairy MTB ride, but is way more less likely. I also cut down the regular clamp-on handlebar grip to match. So far I'm liking it. Click image for larger version

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                Comment


                  #9
                  What gets me is the bike fell to the non drive side. The injury was to the leg that couldn't possibly be pinned. BBSO2B spins at like 120rpm max. That 2 rotations per second. 10 seconds of run time is 20 revolutions. The chain guard on my BBS02B is smooth plastic with a soft rounded edge on the od.
                  I could understand if the right leg was pinned under the bike and the weight of bike and rider was holding the spinning guard against the leg causing pressure and friction.
                  I'll keep using my BBS02B with spinning chain guard as is.
                  I think this is a case of the most unlikely circumstances happening.
                  I have seen similar injuries from bare chainrings before though.

                  Comment


                    #10
                    Originally posted by Dshue View Post
                    What gets me is the bike fell to the non drive side. The injury was to the leg that couldn't possibly be pinned. BBSO2B spins at like 120rpm max. That 2 rotations per second. 10 seconds of run time is 20 revolutions. The chain guard on my BBS02B is smooth plastic with a soft rounded edge on the od.
                    I could understand if the right leg was pinned under the bike and the weight of bike and rider was holding the spinning guard against the leg causing pressure and friction.
                    I'll keep using my BBS02B with spinning chain guard as is.
                    I think this is a case of the most unlikely circumstances happening.
                    I have seen similar injuries from bare chainrings before though.
                    Yes, this case here may just be the perfect storm of unfortunate circumstances or even along the lines of not having the rest of the story. Or...and I hate to suggest that someone would do this, but...a fake story put forth on the internet by someone with too much time on their hands. Not claiming that to be the case here. Weird stuff happens, but that looks like a lot of gnarly injury for the described circumstance.

                    It does give one pause to think about the motor on our bikes and how controlled or out of control it can be. My mountain bike has a big, 42T Luna Eclipse chainring. I can try to envision some chain of events where I'm going through a rock garden and crash with the drive side falling into my right leg and pinning it under the chainring with a full-grip twist throttle jammed wide open because of a rock or the ground. Now you have a meat grinder working away on one's leg.

                    However, think about that scenario for a minute. It would somehow also require the crank arms to be spinning with pedals flailing away. How would that work with your leg pinned or caught at the chainring? I'm not claiming that it's impossible, but it would take an unusual set of circumstances.

                    Comment


                    • AZguy
                      AZguy
                      Giga Member
                      AZguy commented
                      Editing a comment
                      Crank don't spin when the motor turns unless something external spins them - that's what the pawl freewheel clutch does

                    #11
                    AZ, you mean it's not a "fixie"?...LOL! Not sure why that escaped me in my thought process. And obviously the chainring will be stationary too. You'd think I never worked on a bicycle...LOL! I guess I was just trying to imagine what happened to the guy in the pic above. But it is the internet...and I stayed in a Holiday Inn Express last night. You know...the more I consider that fellow's injuries, the more strange it sounds. However, I refuse to join Facebook, so I can't really go read the gory details of the incident. Who knows.

                    Comment


                      #12
                      A bare chain probably wouldn't have done that. The thinner chain guard could. It would probably require something along the lines of a European style enclosed chain case to keep that from happening. I could easily see hitting the throttle when trying to catch a falling bike. Looks like a shark bite wound.
                      I would like to see the chainguard in question. Normal ones attach at the outer edge of the chainring and shouldn't allow a deep cut. Does it attach all the way in at the chainring bolts?

                      Comment


                        #13
                        The guard on my hub bike (I know this is a mid but a guard is a guard) has a shallow chamfer on the outside that brings it not quite to an edge on the inside - resembles a meat cutting wheel and I could see it potentially slicing up a leg like that on a mid

                        I agree that a bare chain is very unlikely to do anything remotely like that - it'd probably just make your leg greasy.. the part of the ring without the chain might do some grinding/cutting I suppose and will definitely grab pant legs if they get in there

                        I never put a guard on the mid drive - I loan the hub a lot so it's good for folks that might not know to secure their pant leg... on the mid I always wear a pant leg clip when in long pants but I also wear shorts at times

                        Comment


                          #14
                          Originally posted by TNC View Post

                          Agree with you on the half-grip twist throttle if one is wanting a twist throttle. Even people used to full-grip twist throttles on motorcycles can have a learning curve with how twitchy twist ebike throttles can be. By "twitchy" I don't necessarily mean that the power doesn't come on smoothly. I mean that they are usually responsive enough that just an accidental rub by the hand or something else can cause the bike to get away or at least be an annoyance. I'm a motorcycle guy used to a life long throttle exposure, but motorcycles as a general rule have a clutch when they're in gear, and nothing happens until you let the clutch out even if you have the throttle pegged wide open...LOL! Most ebike throttles are more like having automatic transmissions in vehicles with the selector in drive...ready to go at the touch of the accelerator pedal. This is a good thing, but not when the throttle gets bumped, grabbed, or hit accidentally.

                          At this point I've tried the Bafang universal push forward thumb throttle, the Bafang side push thumb throttle (like an ATV), the full-grip twist throttle, and the half-grip twist throttle. For mountain biking in technical terrain the universal forward push thumb throttle was safest as it's more out of the way where I had it mounted on the left handlebar side. However, it wasn't as intuitive to use for a motorcycle guy like me. The full-grip twist throttle ended up being too touchy occasionally, even brushed by branches or when I'm wrestling with the bike dismounted in a precarious position.

                          The half-grip twist throttle has turned out best for me as it still has the twist grip throttle function but without all the exposed "live throttle" to the end of the bar. I even cut the half-grip down a little as I felt it was too long for my preference. Mine is now more the size of something like a Grip Shift shifter toward the inside of the bar. Cutting down the half-grip was easy as there are no electrical components on the end. This setup can still be bumped or accidentally grabbed/twisted in a hairy MTB ride, but is way more less likely. I also cut down the regular clamp-on handlebar grip to match. So far I'm liking it. Click image for larger version

Name:	IMG_20210731_130204254.jpg
Views:	298
Size:	1.93 MB
ID:	133488 Click image for larger version

Name:	IMG_20210731_142412549.jpg
Views:	278
Size:	2.68 MB
ID:	133489
                          Thanks so much for all of this info...I too am am MC guy. Did not really like the thumb throttle on the Left. So I bought a full twist grip throttle for my Luna Cycle Apollo. I agree that a full throttle grip may be too much. Like you say on a motorcycle you are using the throttle full time and in coordination with the clutch. The throttle on a Mt Bike is different in that it's only occasionally used. I like your modification to make it like a Grip Shift. I guess the lock ring on the grip does not bother you....So I will try the same mod as you did.

                          Thanks so much again for your info!

                          Comment


                            #15
                            Back several years ago, when I was new to to the ebike scene, I had just folded my Montague conversion and was putting it in the hatch back, when I hit the throttle. Turns out, I had left it on, and it was quite the wrestling match for a few seconds, but no injuries.

                            Comment


                            • AZguy
                              AZguy
                              Giga Member
                              AZguy commented
                              Editing a comment
                              Fortunately my batteries come off in seconds and most of the time I'll pull them off when transporting if only for weight

                              I also set the timeout on my system to one minute, long enough not to shut off at a short stop but quick enough to prevent surprises and if it does turn off it only takes a moment to turn back on anyway... if I'm sitting on the bike at a stop I'm often nudging the throttle from time to time too which resets the timeout and if you have brake sensors that might do the same...

                            • Retrorockit
                              Retrorockit
                              Giga Member
                              Retrorockit commented
                              Editing a comment
                              A 2HP BBSHD is getting into chainsaw territory.Probably wasn't at 100% throttle. That could have ended badly.
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