Bristol folk help

For second hand road and mtb try Bristol Bike Workshop on Colston St.

You could try Velo Club Bristol they do Tuesday night rides and Si at Webbs Cycles has a hire fleet and is a top bloke

I am not aware of anyone in Bristol who hires bikes on long-term arrangements. Nor can I think off-hand of anywhere I have seen road bikes for hire. Asking for both is likely to be a long wait I fear. I may be proved wrong but I'd suggest you launch a plan B whilst you're waiting. There's quite a few bike shops that regularly have second-hand bikes for sale outside (Cyclelife on Stokes Croft, Bike on Queens Avenue, Psyclewerks in Cotham - there are plenty of others depending on which bit of the city you're in). However in my experience (And I do look every so often just in case) these are usually hybrids and ones of a utilitarian rather than a sporting aspect. Unless you're very easy to please it's again unlikely you'll find something that is the right size, cheap enough and which you actually want to ride - particularly if you're serious enough to want to go training. I don't think this is unique to Bristol.

You're either going to have to buy second-hand from a private sale found on-line (The Bristol Evening Post is the local rag - and I say that literally). Or you buy something cheap-ish new and try selling it (or take home the salvageable spares) when your finished.

Local cycle clubs who might have members looking to off-load something are: Bristol South CC, Severn Road CC, Bristol Cycling Development Squad (who might do evening sessions) and if you're around the M4/M5 northern fringe there's Chipping Sodbury CycleSport. There's probably a few others I forgot so apologies if I've offended anyone. Overall there's a lot of cyclists around and a lot of employers who run various cycle-2-work schemes so there should be a good supply of second-hand bikes.