Righto. Llangennith is a dead-end, tarmac-wise, so your exit is Eastwards. I don't do GPS - sorry - hopefully the below will make sense when read in conjunction with Google Maps or OS Maps.
A suggested loop of the north peninsula - prob about 30 miles:
Head east out of Llangennith. Take
a right at Burry Green. Then a
left signposted Fairy Hill and Reynoldston. Ignore the two left turns on the next corner and bear right towards Reynoldston. You're now on a bit of a drag upwards that becomes more open and sheepy and moorlandy and brings you along the top of Reynoldston village. It comes out on a green,
above an impressively-located boozer called the King Arthur. Turn left and you're facing a short, steepish climb over the ridge. If you were on an mtb, you'd get off the road at the top where all the cars are parked and head east up to the top for some spectacular views - but you're not, so just roll over the top and you're looking at the fastest long descent on the peninsula - you can clock something approaching 50mph on this if there's no headwind and you fancy it, but watch out for animals that might wander across your path, and possible idiotic manoeuvres from motorists. The steep bit will run off into a flat section past a pool on the left, and your momentum will take you to the T-junction at Cilibion, where you take a left onto the B4271 towards Llanrhidian. After less than a mile on this, you want
a sharp right turn up a hill, signposted Welsh Moor. It has a blue cycle route sign. The climb can be a bit gravelly, but you're now on the Cilonnen Road - one of the nicest on Gower. It's about six miles long (ignore all turn-offs and
bear right at this little junction) and brings you out on the Tirmynydd Rd. Turn left. You go past a post office/shop on your left and up a short climb to another T-junction.Turn left. You'll pass a pub called the Poundffald (currently closed). Go straight on. You're now on Cefn Stylle - the build up to a lovely long swoopy descent. There are a couple of very steep sections after a farm on a left hand corner - after that you can afford to let go a bit, but do cover the brakes because it's rare to be completely uninterrupted. You'll come out at a T-junction with the B4295. Take a left (signposted Penclawdd/Llanrhidian/Llangennith). This road is a bit dull but it's flat and fast. You may get impatience from motorists because there's a cycle path parallel to some of it, but they can be safely ignored. The road snakes tightly through a village called Penclawdd, then opens out with views over the estuary to your right. About half a mile ahead there are
two consecutive right turns with loads of industrial estate type signs - take the second of these into Pencaerfenni Lane. You're now in Crofty - it doesn't matter whether you take the left or right fork through the village, as they both bring you out on the Marsh Road, which does what it says on the tin. It's a lovely flat three-miles with great views. It can feel exposed in the wind and it floods on very high tides! As it comes off the marsh it will become a narrow twisty lane which brings you to the bottom of the village of Llangennith. If it's evening and sunny, The Dolphin has a nice pub garden for a pint. It's a steep but not very long climb out of Llanrhidian, bringing you back onto the B4295. Take a right. If you're knackered you can keep going straight on and it will bring you back to Llangennith with only one uncalled-for gradient. If you're still feeling lively take the right fork by the Greyhound pub at Oldwalls - it's a lovely road, mostly rolling, with a couple of sharp ups. You'll pass the Britannia Inn (another nice summer evening pub garden). If you go straight on beyond that it's a dead end, but there's an excellent community shop that is great for coffee and cake. If not wanting cake, take the very sharp left after the pub. This is a steep climb, but its reward is a fantastic descent with a long straight run-off past Kennexstone camping - this is Kyfts Lane, and it emerges on the main road to Llangennith again - turn right and you're home.
Other things to note:
There are lots of nice bits of South Gower. The A4118 South Gower Road is nice in itself but is plagued by lousy and impatient driving, and is busy at weekends (especially in good weather). It requires assertive cycling - if you're happy taking a strong position and holding traffic back as necessary, you'll be fine on it. If you prefer to hug the gutter and hope, your nerves will be in pieces from the close passes and the cutting up. Its toughest climb is out of Parkmill going west - other than that it is mostly gentle ups and downs and a few moderate climbs.
Dropping south from the A4118 road to Oxwich or Port Eynon leaves you with some steep climbs back out. Rhossili is definitely worth a visit for the view over Worm's Head, but it's another dead-end.
There's a handy road through Lunnon that joins up the B4271 with the South Gower Road, but if you ride it northwards the climb out of Parkmill is hellish.
There's a similarly handy flat connection between the same two roads, further to the west, between Llethryd and Parc Le Breos, but it involves a few gates and a disputed right of way, plus some rustic surfaces.
There's a disused railway bike path (part of NCN4) that leads from Gowerton, gently downhill through the Clyne Valley to Blackpill on Swansea Bay. It can also be picked up at Dunvant or Killay, and is the easiest way to get from town or the Bay out towards Gower without any serious climbing.
NCN4 can also take you out of Gower to the north/west, across a nice road called the Pont Y Cob Road. Once you're across the Loughor Bridge, the NCN path (although scenic) becomes convoluted and of variable surface, so it can be advisable to take the rather dull adjacent main roads instead as far as the North Dock in Llanelli, where the wide and beautifully-landscaped shared path becomes worth riding again as far as Burry Port. A really nice (mostly) flat ride is to carry on on-road thereafter through Pembrey and Kidwelly, take a left after the bridge in Kidwelly where a short bike path through a park will join you up with a lovely coast road to Ferryside. The ferry cabin cafe is brilliant and you can get a train back to Gowerton or Swansea from Ferryside. Or take a train out and ride back if the wind direction demands it.
If you depart from the coastal route, Carmarthenshire is hilly. Like,
really hilly... If you want to go somewhere tough, spectacular and hilly, then Carreg Cennen Castle is my recommendation - but it would be about a 60-mile round trip from Llangennith.
