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Went Over a Huge Crack in the Road...Ride Not as Smooth Now


Eric Fu

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I was riding in the city and there was a huge crack in the road with around a 4-5 inch height difference from the first part to the next part. I decided to ride through it at around 12 MPH like it was a a huge bump. Ever since then, my Inmotion V8 doesn't feel as buttery smooth as before and walking it occasionally is a little louder with me being able to hear the wheel mechanism. I was wondering if anyone else has experienced it and how to open the wheel to fix that part? I can still go pretty fast and control the wheel like normal, but I want to make sure I didn't displace anything.

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You may have bent the rim/outer hub.  That could explain the increase in noise and change in ride feeling.  The tire spins on the rim / hub assembly which is supported on either side by two motor covers.  The rim is attached to the magnet hub, and if it becomes out of round it can be difficult to repair.  Other than a new motor, I'm not sure what else can be done to improve things.  What tire pressure are you running?

If you look at photos of the inside of motors, you will see a very small clearance between the magnet and the stator teeth where the copper wiring is coiled around.  With a hard impact against the outer hub ring that supports the magnets, it may have warped it enough to change that clearance at the impact area.  That's just one guess, and there may be other reasons.

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I think the pressure is at 3.4 Bar. Also do you know if you are suppose to kinda feel the light clicking of the motor mechanism when you move the wheel back and forth via hand? If this is a warping of the outer hub, I'm willing to take it apart and try to unwarp it. I swear it was more smooth before, but it might have just been my imagination.

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I've never had a clicking feeling moving my generic wheel or Ninebot by hand.  You might check to see by allowing the tire to rotate freely whether it is out of round.  Maybe if you're lucky it could be just the tire?   You could remove the tire / inner tube and inspect to see if there is any damage to the rim and whether the hub is damaged.  Maybe the impact shifted the air valve?  Did you check to see if it's still in position?  It might have shifted if you hit the tire near it resulting in it bumping against the inside of the shell?

Thinking about it more, I wonder whether the hub could be warped since the side covers give it quite some support.  I think it would take quite a lot of force to deform it.  Maybe inspect the tire and rim for any damage.  I wouldn't take apart the motor until it was proven that there was a deformation present, but even still I think it would be very difficult to fix.  Hopefully that's not the case!

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Clicking might be too strong of a word actual. It is more like I can feel the movement of the wheel like if I was literally pushing the wheel and doing the work of the motor.

Air valve seems fine and lifting the wheel up while it is on seems to act normally. Plus I can still ride it at max speed. Have your wheels ever felt like they changed after going over big bumps?

 

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Take it to a bicycle shop. They will be able to use this caliper thingy and spin the wheel to see if it is out of round or if your rim is bent.

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I've hit a few bumps on my wheels, but nothing extremely bad to have caused a change in the feeling of the wheel.  I wonder if you might have a slightly damaged bearing.  I have noticed that over time my Ninebot bearings feel a little more rough as compared to when it was brand new.

How does the wheel spin with it turned off and you turning the wheel up in the air? And while off if you push it on the ground?  Any unusual grinding sounds?

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I take my v8 off of curbs all the time and I haven't had any problems.  I get a noise every once in a while but I usually attribute it to water or debris of some kind getting into the wheel because it usually goes away in a short time.  I weight about 190lbs, so I'm pretty sure that the wheel can take some pretty good abuse from a pothole.  I know how sensitive I am when the wheel seems to be acting or sounding differently, so I don't want to suggest that you should ignore anything, but I also don't have the technical experience of opening the wheel so I can't encourage you to go that route to solve your problem either.  If it were me, I'd get in touch with my reseller @Jason McNeil, who never steers me wrong.  Hopefully you've got a resource like that to help...good luck!

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Thanks for the replies everyone! I think I was just paranoid as I never went over a bump that big before and got a little oversensitive. Since the wheel itself does seem to function abnormally, I'll probably just leave it like it is. Everything else like the wheel spinning in the air seems to be just fine.

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You can check to make sure you haven't bent the axle, some KS-riders have had problems with cracked axles. But the hub should be able to take the strain, it is by no means fragile. Given the situation, I would say the parts that probably took the brunt of the force was the axle and the bearings. A overloaded bearing sounds in line with the symtoms you describe. It might well work, but even a small irregularity could make it feel a lot less smooth.

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@Eric Fu, I think the "clicking" you are hearing might just be what is usually called "cogging" (see:https://www.rcgroups.com/forums/showthread.php?28021-Brushless-motor-cogging-What-is-it) This is fairly normal depending on the motor construction.

If the crack you went down was not enough to throw you off it really shouldn't have harmed the wheel unless as @Hunka Hunka Burning Love Suggested tyre pressure was low enough to damage the rim. I go over some pretty evil speed humps regularly with no problem and drop down off of kerbs as well and that's with a more vulnerable 14" wheel.

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