Which are the best type to go for? I've used a 3 roller set up before but a quick scan around and looking on Ebay seems to show the single rear wheel jobbies are now more prevalent. Also used to use my mates with a road bike. I take it there would be no problems using one with an MTB? What about off-road tyres I'd imagine a spare wheel with a more "road" tyre would be a better plan. Cheers in advance.