Water is essential for long bike rides, particularly when the weather is hot. However, electrolytes are just as important for very long and/or hot rides. Hyponatremia is a potentially fatal condition caused by very low levels of sodium, and long-course racing, particularly the Iron distance, can put one at risk if they are not careful about adding in electrolytes along with water consumption.
Electrolytes can be found in many drinks, though that isn’t the only form. I have something called base salt that I have used on bike rides – it is literally salt (specially formulated to replace electrolytes related to exercise) that I keep in a tube and can open, like my finger, dip it in and just get some salt. This is appealing to me for an iron distance race because it isn’t easy to carry all of my own nutrition, but the salt can fit in my bike jersey to have to supplement the on-course nutrition and what I do end up carrying. There are also salt pills on the market which I haven’t tried.
It is also possible to consume carbohydrates and other nutrients in liquid form on the bike. There are numerous products on the market that provide calories from different sources and serve as different ways to get electrolytes. I’m quite certain that one could get sufficient calories for a full day ride through liquid nutrition alone (though personally that seems far less fun). At least one company allows you to create your own custom mix.
What I do most often, and have for a couple of years — though honestly with differing variations of the amount of each depending on my daily whim, or sometimes more calculated if I’m really trying to consume a set amount of calories — is EFS Lemon-Lime electrolyte mix along with CarboPro – which is straight carbohydrate powder made from corn. It doesn’t even have any taste. Trust me – I thought it was hilarious the first time I started using this. Normally I limit carbohydrate consumption, and to be consuming carbs that don’t even have any flavor seemed, well, just hilariously ridiculous.
Regarding amounts, I will say that I never use even close to the recommendation on the package. That may work for some, but I think I have an ultra super duper slow metabolism, and I often go slow enough that I think I am consisting mostly on my stored fat.
For racing, one thing I have done with liquid nutrition, is to carry one bottle that is hyper concentrated. I add it to plain water that I get from the aid stations.