Signed up to do Kielder this year and training is going ok so far.
Been reading up about the route as this will be my first time and most people say its not too technical. It got me wondering if a cross bike might be the best option to keep the average speed up and so get round or are people underselling how tough the route is??

They let them cheating feckers on 29ers enter so might as while let the closet roadies in on CX bikes

if your skills are upto it, probably not that much to trouble a good cross rider in short bursts – but mixed in with 100 miles! i would have thought comfort would be an issue.

does say it’s a mountain bike race .

pretty sure cross bikes aren’t allowed.

Just checked and you are correct.
That answers that question, need to find another way to get round in the time limit!