Fixed mountain climbing gear. Help please

I'd buy a cheap 170 mm - 175 mm sora or what ever cheap crank set and use the inner ring to give me a easier time to get the low gear.

You're the man who has done this ride before so really have the best chance of working out what you need.know

Last year I did it on a unbranded hybrid, which is too big for me, and fecking heavy. I did'nt really train for it either, as I had just completed the local marathon, and was knackered.

Its a bit hard to transfer my experiances last year to riding a, far lighter, fixed road bike. Hopefully after completing some training, my legs will work better this year.

Sounds like I need to go lower than 42:22 so I will try to sort a 41:23 set-up and see how it goes, in training.

If it doesnt give me enough spin spin, Ill start thinking about swapping out the chainset.

Thanks for the input ;)

PS. @andyp were can you get hold of these huge cogs?