Being a Rasenite (how Market Rasen locals refer to themselves) I know the wolds very well indeed. Despite popular misconceptions, there are some hills in Lincolnshire. Granted, they are not that big, given that the highest point (rather unimaginatively named Wolds Top), which is near the Claxby radar installation (known locally as the golf ball after its shape) is only 168m high. Due to the geographical nature of the wolds, the hills tend to be short and steep rather than long and sustained with the bigger hills being in the north (mostly off the B1225 Caistor High Street). The notable hills are 1) Bully Hill on the B1203 between Tealby and Binbrook. 2) Walesby Hill on an unclassified road between the village of Walesby and the B1225 Caistor High Street. 3) Normanby-le-Wold hill on an unclassified road between the village of Claxby and the B1225 Caistor High Street. At the fork, you can either go right (passing the council houses) or go left. Either way, head towards the golf ball. The right fork is steeper and shorter than the left fork. 4) Willingham hill on the A631 between North Willingham and Ludford (this is a busy main road so be careful). If you want a nice circular route that will get some climbing in then try this:
Starting at Market Rasen (cheap / free parking in most car parks). Head toward Louth on the A631. Take the right turn signposted to Legsby and the Barkwiths to a hamlet called Little London. Here take the the left turn to Sixhills. Go up Sixhills hill and continue to Hainton. Carefully cross the A157 and head to South Willingham. When leaving South Willingham turn left towards Donington on Bain passing the Belmont TV tower on your right (careful crossing the B1225 as motorcyclists regularly ride down here at 100+ mph). Just before you reach Donington take the left towards Welsdale Bottom / Hallington. At the next x-roads take the left down the bluestone heath road. Head towards Kelstern crossing the A157 (staggered left right) and A631. Pass through Kelstern and at the multi-road junction (known locally as 5-ways) take the 1st left to Great Tows, where you turn right down a road called "The Switchbacks" towards Binbrook. For interest, as you descend into the village, just as you get to the start of the houses, if you look to the left you will see a Lightning jet fighter (XR725) in Charles Ross's front garden. From here, take the left turn at the junction (signposted Tealby / Market Rasen), then at the sharp left hand bend turn right towards Brookenby. Keep on the main drag all the way to Rothwell (passing through Thoresway). In Rothwell turn left at the pub towards Nettleton (again crossing the B1225). At Nettleton take the left turn signposted Normanby-le-Wold. Pass the golf ball and drop down Normanby hill into Claxby. From Claxby you have 2 choices. Either A) take the main A46 into Market Rasen. This is a busy trunk road frequented by piss-poor drivers, so take your chance or use the path on the right hand side that starts at Walesby turn-off. B) Turn left and immediate right towards Osgodby, take the first left before the village towards Middle Rasen, go through the village to meet the A46/A631. From here there is a bike path back to Market Rasen.
Taking the longer route via Middle Rasen (B) the route is just under 40 miles with 2362 feet of ascent (max elevation 531 feet).