Just because the map says 'bridleway' does not necessarily mean 'this will be a nice route to cycle rather than walk'.
I should probably learn this lesson, and do more google maps spying when planning stuff (in fairness, I had done some...). Especially when the bridleway in question is on top of a small Welsh hill where it's been raining on and off for a few days...
Builth Wells to Erwood, along the Wye Valley Walk. Starts off on country roads and tracks (including some steep bits which I walked). Then you get further up the hill, and the path heads off road onto the common.
And staying on the bike becomes impossible, as it's so boggy underfoot. This is also not ideal when wearing trainers, which are definitely not in any way waterproof. Soggy muddy feet, lovely...
Getting back on the bike to head down the other side of the hill: again not brilliantly sensible. Always fun to have both sets of brakes lock up, both wheels caked in mud sliding in all directions all over the place, and realise that the only way of stopping is to fall off the bastard thing. Muddy bum. Ouch
Needless to say, I was quite glad to reach actual solid road again! Even if it did involve a short section of A470 (ie getting overtaken by lorries - luckily a wide section of road so not too scary) before turning off over Erwood bridge to head back to Builth on the quieter B4567.
mmm, traffic free cycle path
This also forms part of NCN8, aka Lon Las Cymru. I've got the guidebook for that too, because I like guidebooks and it follows the Wye between Llangurig and Glasbury... The book's dual language too, which is quite cool - English and Cymraeg, which I understand about 10 words of. haha
Anyway, I digress. The cycle back was a lot quicker than the walk/cycle out. As in, took just under half of the time... The final mile into Builth is on a lovely traffic free section of cycle path.
My Wye progress bar currently says 82%. This is based on a total distance of 220km. however, having looked at what's left to do, it's actually going to end up nearer 240km in total, so I need to tweak my code a bit! I will speculate where I've gained nearly 10% from at a later point.