Can anyone recommend a good one?
Coombes Cycles in Hereford is very good.
Climb on, round the corner from Coombes.
Although, it's been a while.
climb on
Climb on Bikes, great shop, great staff.
Mark in Coombes Cycles has always been very helpful in the past (a proper 'old skool' shop), but as the two shops are within spitting distance of each other, why not visit both?
Gateway or M&D Cycles both in Abergavenny
559 Bikes in Chepstow
A it further away but worth the effort
Castle Bikes in Caerphilly - Jimbo the mechanic, is a top lad there
EC Bikes - in Nelson, a new shop, Dorian the owner is fab
depends what you are after???
...then there's 'Revolutions' in Ross-on-Wye.
Another vote for Mark at Coombes. He's a first class wheel builder and they're a Hope Pro shop too. There's undoubtedly more stuff in Climb On, but if you want proper friendly service, Coombes is the place to go.