V13 Electric Unicycle Inner Tube Repair

  Addressing an even that should not have happened

Event Report 20231111

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Background

We have a number of electric unicycles (EUC): 3 V11 models, one V13 and one V14.  The V11s have seen some hard service and have several thousand miles each.  The V13 is new and I was surprised to find that the tire went flat shortly after delivery.  The problem was the shitty Chinese tubes that were in the wheel.  Sadly, through predatory pricing practices, there are no other versions of these tubes with the market having been cornered by Chinese.  So, the action here is to replace a known-bad tube with a possibly better tube from the same vendor.

The Solution

These days, when you purchase a product, independent of cost, you will not get a user's manual or instructions.  These come via the web or Youtube.  Instructions for servicing the wheel were contained in a YT video.  So, without recourse, I used this video to learn what needed to be done to remove the wheel and then gain access to the inner tube.  The V13 was supposedly designed with maintainability in mind.  The V11 tire change is a big deal and required almost complete disassembly of the device to extract the wheel.  The claim is that the V13 is "better".  We will see.

The photos below are what we saw.



The V13 is a BIG wheel - heavy and awkward when stationary, it weighs 120lbs so it requires support to stand vertical safely.  I used some large hydraulic cylinders that I had as the braces.


First, the trolley handle is removed.  The handle is robust, but the mounting conflicts with removal of the top of the machine.  With only a small number of exceptions, all screws required a hex key for removal.


Once the handle is off, the rubber covers for the rebound shock adjustment are pulled.

  Front and rear handles needed to be removed.


The handles needed to be removed to allow access and removal of the top plate.


Once the top plate was removed, access to the motor control wires was possible.  Since these wires go directly to the motor (inside the wheel assembly) they must be removed to allow separation of the wheel assembly from the battery/controller assembly.  The bolts holding the shocks must be removed as well.


The motor is a 3-phase brushless DC design.  The phases are not interchangeable, so care is needed to not confuse the wires.  The wires are both color and length coded.

Once the required items have been removed, two strong bodies can lift the battery/controller assembly off the wheel assembly and be placed aside.


Two shocks on each side: one compression the other rebound.  The rebound shock is the one with the hex stem on it.

The shocks needed to be removed from the guide assembly by removing the nuts at the lower end of the guide extrusion. I marked them with tape to insure that left and right sides were not mixed during re-assembly.  Not sure if this was needed, but easy to do and prevents possible secondary issues.

A view of the lower end of the shock guide assembly.  The red plug allows access to the Schrader valve fill port.

The orientation of motor assembly was noted.

Left and right shock guides, trolley handle and top plate are visible in the photo above.

Internal fender was separated.
 


The wheel/motor assembly was separated and the actual inner tube replacement can begin.

This was a bigger job than I expected, but way easier than the V11.  That said, it should not have happened at all.  The tube developed a bubble and started leaking air immediately, the sign of a really poor quality product, as is typical (or even expected) from vendors in that part of the planet.

As an end note (written in 202408) access to the shock filler valve is not possible without removing the end cap of the shock guide assembly.  The design did not allow for the short stems of the shocks and no changes were incorporated, so partial disassembly is required to inflate/check shock inflation.  Ugh.


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