Oh! Oh! Oh!
That is dreadful, terrible luck you had with your AXA Solid Plus frame/ring lock, Richard, and I'm so sorry. What a pity to sustain such damage, and a bit of luck you did not suffer a fall or injury. Your caution to others is surely well-advised.
In response, all I can say is I selected my AXA Defender and Victory frame locks and my Trelock 4500 Balloon lock to be the key-retaining kind, as it seems you have also.
*Normally* this sort ensures the lock cannot be locked and still retain the key. Also *normally* regardless of key retention, there is an interlock so the lock shackle cannot be thrown shut unless the key is twitched as the lever is moved. This feature dates almost from its inception as a child-safety feature. At least anecdotally, there were a few instances of Dutch mothers losing their teeth when Junior in the child seat got bored and decided to play with the lock (!) while underway; a hasty redesign soon hit the market.
Obviously, something went Very Wrong with that here...I'm guessing the key was slightly turned and bent by impact, allowing the shackle to close without intervention when you back-pedaled and hit the actuation lever.
Your clear account is really helpful and -- yes -- I think the same unlikely and unfortunate series of events could cause the same effect on other frame/ring/wheel locks, so your caution is duly noted and much appreciated.
A couple of general notes to others using such locks:
1) Unless your frame is equipped with mounting bosses in the seats stays (basically bottle basements threaded M5 x 0.8 ), you will need to rely on some sort of mounting adapter, as supplied by the lock makers and often available as a separate item. Install these brackets with thread-locking compound on the mounting hardware, and check them periodically. Some are more secure than others and a variety of factors can make even the best mounts more or less secure. These factors include seatstay diameter and spacing.
2) As I recall, the AXA Solid Plus is not rated to be as secure as the Defender or even newer Victory models, which can accept even large diameter plug-in chains to augment and increase their effectieness. The Solid's basic constrction is less robust (i.e. not fully perimeter welded case halves, as with the Victory) and has less robust plug-in options.
All the best,
Dan.
