Re-hydration salts are actually a much better alternative to sports drinks, well done you.
Why? Interested to know what this is based on.
The way I see it... Dioralyte, for example, has to be used within an hour of mixing and only in a 200ml dose, this effectively means that it can only be taken at the end of the day or at convinient stopping points each day where fresh water is available in 200ml measures. You're basically running down your bodies reserves during the day and hoping that you'll do enough to top them up in the evening or whenever you get a chance to sit down and mix up a 200ml drink. The cost? £3 per litre!
Something like a High5 Zero tablet can be popped into the days waterbottles so you'll be topping up your 'salts' as you ride. They make a neutral one with no taste, so you can pop it into whatever drink you like.
Its cheaper too. £6 gets you 15 litres worth of High5, thats just 40p per litre.