An Olympic level coach (admittedly not cycling) told me you can get close to full fitness in 12 weeks.
I think that rather depends on the starting point
An olympian who has been out from injury may be able to but a couch potato who is 3 stone overweight has no chance.
My advice do the ride enjoy and next year be faster ..I have agreed to do the Fred whitton this year but not on race day.
Quick update.. Feel a lot fitter in just a week.
Basically just been pushing myself on every ride.
Riding to work has really helped as there's 1000 ft of Climbing in 10 miles.
Average speed is now up around 16mph but don't know if I could do that for 75 miles.. Yet
Still haven't committed to entering.
Intervals. When riding attack hill or better do a hill repeats. Pick a hill that is 2 to 3 minutes and sustain a constant hadd pace. For me and mh low heart rate thats 150bpm. You want it to be below threshold and use a high gear so cadance is below 60 rpm. This builds strength in your legs and allows you a later date to build higher intensity threshold or past threshold intervals. Doing high kntensity trianing without sufficent base miles and strength work is like having jam without toast. Yoh need a base to build one and doing the base work will improve the pace you can ride at if that is your goal. It will hurt though.
What you need to do is avoid that zone where you pushing your self but yoh get little fittness gain. That is somewhere between threshold and your endurance pace. Base miles at endurance while spinning at high cadance pace and do puchy strength intervals and that will see you right.
8 weeks will get you in a decent enough shape to survive it and even enjoy it at a decent pace >>
http://www.amazon.co.uk/Time-Crunched-Cyclist-2nd-Ed-Powerful/dp/193403083X
There are some dammed hard intervals to complete in the 8 week plans but they are based on that goal of doing a race/event at the end of the eight weeks.
