the mystery of the broken bicycle tyre inflator
 

The uncanny breaks into everyday-life spontaneously and unpredictably. Today it hit me for the third time. The first two instances were “The riddle of the vanished filling station attendant” and “The amazing locked away broken flask” which I may relate at a later date. In both cases it took me quite some time to construct satisfying explanations for the events experienced. For today’s phenomenon I still completely lack an explanation.
 

This morning I rode by bicycle to the office. Early on my way I realized that there was way too less air inside the rear tyre. So I stopped at the curbside, got myself off the bicycle and the tyre inflator out of the rucksack. I own a single stroke mini pump with alloy barrel and ergonomic T-handle by Scott USA. The pump’s special feature is the handle, which very conveniently can be rotated by 90° into operating position, allowing an ergonomically good grip while pumping:
 


 

It’s my habit to count the strokes in order to get an idea of how much air I actually force into the tyre. Exactly at stroke No. 101 the pump came apart. Meaning that the T-handle still was in my right hand, but was nor more attached to the piston’s stem. The pump is already since several years in my possession and was much used, and after enough time tools brake. No big deal. Thing is, it was, and still is, not broken. I will explain the matter—have a look at the picture, which was taken within the first minute after the occurrence of the phenomenon:
 


 

At the end of the piston’s rod or stem a pill-shaped plastic piece is screwed on. This piece features a drill hole through which the aluminium axis fits, around which in turn the handle bar can be rotated 90°. At stroke 101 the handle suddenly was detached from the stem, with the aluminium axis still being in place and the plastic part’s eyelet still intact! So what must have happened is that the aluminium axis permeated the plastic eyelet’s brim, or vice versa, or both, without leaving a trace of this process. Matter through matter! As soon as I had realized that I took a couple of “proof pictures” by means of my cell’s camera. Documentation finished I started to fathom the phenomenon by reassembling the pump. First I had to take the aluminium axis out of its place in the handle. I pushed it with one of my keys as far as possible and then used my teeth as pliers to get it out completely. Then I inserted the eyelet into the handle and pushed the axis back through both parts. Now the inflator is just as it was before and works perfect again.
 

Now the only explanation I can imagine goes like this: You do not pump in a straight line, as a consequence somehow a tiny vector of force builds up, which pushes at the axis sideways. When you pump repeatedly, and I did a hundred repetitions, the axis gets pushed so far to the side that it allows the plastic eyelet to come off. But this explanation seems very unlikely because of several reasons. Firstly, when you pump the axis’ ends are covered and thereby blocked by the two sides of the thumb-crotch. Secondly, when the handle came off I immediately glanced at it and saw the axis being firmly in its correct place. I can not imagine where the force should have come from which could have returned the axis instantaneously to its place. Especially as the axis fits snuggly into the handle’s drillholes and substantial force has to be submitted to push it into or out of position. During the day I dissassembled and reassembled the handlebar multiple times and scrutinized every part, but honestly, I can not come up with any solution.