increasing bike distance

thats not really a big jump, and if you have been riding consistantly you should be fine.

just go out and ride the distance, guide your effort by RPE and have some sports drinks as fuel. If you go to hard you will struggle to complete the distance but you'll learn you need to pace better and next time do a better job, though the adaptations you will gain will make you a tad fitter for the next ride. Don't be affraid to do it, push a bit and see what happens

J

^^^
One of the things I learned from Jorge was exactly that.  It's ok to go push the bike in training.  That is how you start to learn.  You don't know what you're capable of or where your limits are until you go too hard.  I can't tell you how many bike rides I did in a row where i biked too hard and then died.  But each one i got a little fitter from doing it and i grew closer to figuring out what is sustainable.  To the point that I went up and biked 112 miles on the Lake Placid course and did exactly the same time for both loops.  <60 seconds difference for both loops.  And then of course i went up 2 weeks later and tried to bike a teensy tiny bit harder, literally added 1 gear of resistance, and i blew it.  My second loop was 20 minutes slower than my first.  So I chalk it all up as gain...gain in fitness and gain in experience as to gauging RPE.

So I agree w jorge, just go do the distance and see how you do.  You might surprise yourself. 

How about both.  Sometimes ride for longer but at a lower intensity, other times ride hard and see how far you can get.

Ride hard.  Ride lots.