It's been a long time since I've done one and I'm signed up for the Amtrak in So Cal on Sept 8. How many miles should one be able to do prior to the event? I'm feeling pretty fit but most of my riding is only 7-20 mile mtb rides. I've been trying to do more road bike. I got in a very hilly 22 and 30 last weekend (2300 and 2900 ft of climbing) and a 58 miler with 2600 ft yesterday. I'm hoping to do a 70 miler a couple weeks ahead of the century--is that enough? Maybe working with some others event day will ease things up... Thoughts?