I'll be very honest I am the only one who has not read this thread and I started reading it backwards just now, got as far as the gears and am going to comment before I forget, the kids come in and I pop to the shops to get some coke to go with the dark rum.
Why 12 sprocket and not 11 ?
A couple of reasons …
Firstly (and honestly), I didn’t know about 11’s until quite recently…
There is a big gap in my bike knowledge which strangely enough coincides perfectly with my ‘girl’ and ‘car’ era
I seem to remember that BITD a 7 speed 12-28 was the size to have and that a 12 was the smallest ? To be fair though the only other common 7 speed I remember was the 13-30 ?
Secondly, the bike shop that my friend works at only had a very limited selection of 7speed HG sprockets in stock and stock goes cheap due to his staff discount
What I ended up with was the best 'road' ratios they had in the better quality ‘silver’ finish – beggars cant be choosers !
Thanks for all the other nice comments