may i ask what hillingdon is like as a course, i will racing on the 11th but singlespeed, so im thinking 42t-20t to account for the mud that should be there. are there many hills to contend with?
thanks
When I raced there earlier in the season, it was bone dry, but it can get quite muddy apparently. It is pretty flat, they tend to make the most of the slight incline there is by switching the course back and forth across it, but it is definitely not what anyone would refer to as hilly.
Having said that, I probably spent less than 10% of the race in the large chainring. Can't really help with the ratios, as I have never tried singlespeed cross, and cannot even begin to imagine trying to ride a whole course on just one ratio

Hillingdon does have a reputation for killing rear mechs on account of the tough and long grass there, so you'll be one up on the rest of us on that score.