Re:
Kirk problems are mostly related to a failure of one or more of the resin bonded joints
There are tubular inserts bonded in to the headset area , and also the bottom bracket
The rear dropouts have inserts bonded/screwed in to avoid fretting of the alloy by the axle
The various cable guides are all bonded in
Both the seat 'tube' and down 'tube' have panels bonded in to their rear and lower surfaces respectively ,
in my view this is the area of the bike that has produced the most problems . If the bonded joint at the edge of
either or both of these panels fails , the torsional strength of the 'tubes' will be considerably reduced .
The fault will not be visible without minute examination , and the bike will not ride well !
Any loose inserts are best removed , and the old resin removed with a hot air gun , before re-bonding the
components . The top tube cable guides can be re-constructed with resin if damaged .
The hard to find component is the gear hanger , which is a design unique to the Kirk
I have not heard of a frame cracking as such