deffinately doable. September is close but start now and build up a slow but steady increase in your mileage. Do one hard day a week (jumps, hill repeats, that killer spin class), never do that back-to-back and at least one longer ride.

What does NOT work is doing a whole lotta miles right before the event. Build up slow.

Then as I told Lorri, coach/founder of the Velogirls before I went "If all else fails I'll just eat, drink, hydrate my way through the ride". Take care of your body.