Chains only snap because they are badly maintained...for which read, lack of lubricant. I have just returned from a place in Normandy (with 12 other members of my family) that had 6 bikes, all were in a terrible state of repair. I oiled the chains, put air in the tyres, adjusted the seats and away we went, most of them had a little use over the week but as a paying guest, I expected the bikes to be fit for purpose on my arrival...it'd be like a gite owner expecting me to clean a dirty pool, oh and could you just rewire that barn while you're at it. I cannot see a problem at all in getting a few differing size VTTs from say Decathlon, £70 each new, if looked after they will last a few seasons, a list of do and don'ts together with the rest of the house rules etc