I've done the HLifax ones that
@Richard A Thackeray mentions, but on a mountain bike with 22/34 as lowest gear. Elland cricket club to Blackley off road is another bit of a tow, as is Copley to The trig point on Norland Moor.
The first 20 minutes of the Marin trail is a long, steep slog. Penmachno is similar, and The initial climb at Ae forest is disheartening in places.
On road, I have done Blubberhouses and all the long grinding bastards between there and Holme Moss. Don't underestimate the ones that were hardly mentioned during the TDF... Keighley to CrossRoad, the climb up to Cock hill from Hawarth, to name but two.
The A640 from Huddersfield Town centre to Buckstones is a 12 mile slog with only two downhill bits in the ride. Similar the A62 from Linthwaite to Stanage is a bit of a drag too.
Hardest for me was Wessenden fromMeltham. Unforgiving sort of climb with loads of false horizons and a nasty headwind.
I quite enjoy Cragg Vale, in a smug sort of way.