Frozen trails can give you some of the best riding that you'll ever get around here: perfect grip, no mud and no bike cleaning.
BUT BE WARNED! Riding on melting trails can seriously damage your bike. The usual scenario is that the rider's transmission gets clogged with concrete like mud and with lack of previous experience the rider tries to power through, the mech is ripped off, the chain mangled and hopefully the only frame damage is a wrecked rear deraileur hanger - average cost about £100+.
You have been warned!
So get up early and enjoy riding ups and downs that, in normal conditions, are impossible due to the lack of traction. Yes there is more grip than any day in the summer.