Hi
I am doing the ride in August and will be doing spinning classes in the lead up to it.
I have not attempted the ride before, but the spinning I have done over the past 2 years has always helped my fitness.
That said, there is a difference between spinning and hill riding with the wind against you, the latter being far more difficult. I am no expert and everyone has their own views, but I’m planning to mix spinning and road cycling leading up to the event
Johnny