Since this thread started I've modified my usual pre-, during and post-ride drinks and snacks. I just kept experimenting until I found a few things that work reliably and are easy to find.
While most sports drinks and snacks contain the same ingredients, the balance seems to be important... and very individual.
For everyday use before and during rides, one of my water bottles will have a packet of cheap Propel electrolyte powder and a spoon or so of Six Star 3X creatine mix. That's usually good enough to stave off muscle cramps. And the creatine helps with short duration maximum effort bursts, such as sprints, or exercises using weights, body weight or resistance.
For emergency hydration I carry one or two Mylar packets of
Drip Drop. They seem to have nailed the perfect balance of electrolytes and sugar for rapid oral rehydration. Last summer I used it on two different people suffering from heat exhaustion and they felt remarkably well within 15 minutes, and one of them finished the bike ride (albeit at a much easier pace). They both said it seemed to work better than their usual preferred sports drinks.
Drip Drop is a bit pricey, although no worse than any premium brand electrolyte mix. I usually buy it at Walgreen's when it goes on sale and buy two or three cartons at a time. I find the slender Mylar packets much easier to tuck into even my smallest saddle bag, than the Nuun tablets and other brands. Check the Drip Drop website. It doesn't seem to contain anything unique, but they got the balance right. At a buck apiece or slightly less, it's been worthwhile just to see in action how well it works on folks who were overcome by heat and dehydration or improper hydration (such as taking old fashioned salt tablets, usually a bad idea).
In snacks, I've narrowed it down to Clif bars. I like the flavor, texture, price, everything. I've tried every other brand and type available and had to discontinue those using sugar alcohols like maltitol. While sugar alcohols are good fuels, they give some of us terrible gas. It's more funny than uncomfortable -- for me. But it wouldn't be pleasant for anyone riding behind me. Clif switched to plain sugar which works well for most healthy folks, not only for an energy boost when we bonk, but also helps with quickly absorbing water. That's a good thing for folks who don't like the flavor of sports drinks, but do need a bit of help with absorbing water to avoid bloating.
But since this thread started in 2017, I've dropped 10-15 lbs, and adapted to riding farther at reasonable effort with little or no food. I'm not into full keto, but have changed my diet a bit, eliminated most junk carbs and sugars (sorry, Dunkin Donuts, I still love you and miss you, but let's face it... we weren't a good couple), and added more meats, fats, etc. I still take sugar in my coffee, or pre-sweetened Dunkin Donuts creamer (my favorite, and we still have a long distance relationship, sans donuts). I still have maybe 3 lbs of body fat pudge around my belly and hips, but that will come off by itself as I continue long, moderate effort bike rides without eating. I drink plenty to offset any hunger pangs.
My pre and post ride beverage, and sometimes meal, is a shaken concoction of protein powder (usually whey), various additives and supplements, creatine, etc. Seems to help. I may feel a bit peckish during a 2-hour or longer ride, but I don't bonk anymore. Sometimes I'll have oatmeal before a long ride, often adding an egg or two for a nice custard texture and bit of fat for long distance fuel.
Changes in diet and exercise haven't improved my top speed, but my average speed/time over distance is a little faster, so I can sustain a steady effort longer. I'm no mountain goat but my climbs have improved from dead last on every Strava hill segment to middle of the pack.