just single speed?
work out which gear you want to stay in first.
take the derailleurs and shifters off, and take off one of the chainrings on your cranks and replace the bolts with single-chainring specific ones.
then get a freewheel (http://www.pushbikes-uk.com/products.php?plid=m6b174s194p2980&rs=gb) and ask your lbs to re-dish and re-space your rear wheel accordingly and to fit the new freewheel.
just single speed?
work out which gear you want to stay in first.
take the derailleurs and shifters off, and take off one of the chainrings on your cranks and replace the bolts with single-chainring specific ones.
then get a freewheel (http://www.pushbikes-uk.com/products.php?plid=m6b174s194p2980&rs=gb) and ask your lbs to re-dish and re-space your rear wheel accordingly and to fit the new freewheel.