This is quite an old list man, sprotborough aint bad. Don't waste your time going to hexthorpe, it was built by a blindman and his one-armed apprentice.
Maltby is great, don't know who said that was rubbish. It's behind maltby leisure centre but it's in a windy open field so beat to go when it's a still-ish day. also the drain is not in the lowest pat (doh) so if it has piised it down within the previous week it will be 30% puddle. Oh, and take a sweeping brush and a binbag coz the local comprehensive school pupils use the park for a dining room-cum-litter bin between 12.15 and 1.15 during the week.
Pm me if you want to ride the place, im only 20 mins away.
Derby is shut
Dev green good but busy at weekends
Piwheels at upton is small but fun go on tues/thurs/sun for bike nites
Bolehills and chesterfield are the tracks most worthy of a visit.
Happy travels mate.