Have a search for "Magic gear" and "eno hub", you can also use an eccentric bottom bracket.
Of the three options the magic gear will be cheapest, but all share the key advantage that they are known to work, and will leave you with a functional frame afterward.
Have a search for "Magic gear" and "eno hub", you can also use an eccentric bottom bracket.
Of the three options the magic gear will be cheapest, but all share the key advantage that they are known to work, and will leave you with a functional frame afterward.