By "long rides" I mean those over 30-35 miles and lasting 2:30 to three hours or more. (I'm still building up my fitness and stamina for anything longer.)
My "bonking" usually sets in around the 20 mile mark between an hour and 1:15 into the ride. If it's a hot day, I'll start to feel like my legs just can't turn over as quickly and I'm not light on the pedals. By mile 30 I'm usually well off the pace. By mile 40 I'm barely moving up the hills and may even weave a little.
Here are my sure fire ways to guarantee a "bonk:"
1. Do not eat anything before the ride.
2. Do not carry any sports drinks.
3. Do not carry any solid food.
4. Do not carry any energy gels.
5. Do not apply sunscreen before setting out on the ride.
So, logically, here is what I've been doing to prevent such misery:
1. Prepare my fueling plan the night before. Figure out what I'm going to eat before and during the ride. Eat at least 200-250 calories before the ride. Drink 16oz of water and S-Caps if it's above 75 degrees and humid.
2. Mix up 2 pretty strong bottles of Gatorade. Put one S-Cap or Endurolyte in each bottle.
3. Make sure I have at least one Clif bar to eat at around mile 20.
4. Carry a full flask of Hammer Gel (Montana Huckleberry or Vanilla) and draw from it every 15-20 mins.
5. Put sunscreen on the back of my neck, arms, face, etc. prior to leaving the house.
Figure out your own requirements by listening to your body. Spending a little extra time on your fueling plan can do wonders for helping you avoid "the bonk."