it is not the best solution but I do agree with abath just do the best you can and ride. have you tried have the shell 'faced'? it mmight help. also I thought I read somewhere in the last week or so that some one (like VO or one of those 'vintage' places) was developing a BB that didn't use the sheell threads. like the old mavic cart.
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“One morning you wake up, the girl is gone, the bikes are gone, all that's left behind is a pair of old tires and a tube of tubular glue, all squeezed out"
Sugar "Kane" Kowalczyk