1.) 1 gram of carbohydrate per hour per kg of body weight. So if you weigh 75kg, eat/drink 75 grams of carbohydrate (CHO) per hour. This could be as simple as one bottle of energy and 2 gels per hour. Swap a gel for a banana or half a bar every now and then.
2.) Listen to your body. If you are burping and gagging a bit, have some water and give your stomach 30 mins to settle. If you are motoring and feeling great you are probably about to hit the wall so get some carbs in fast.
3.) Drinking is a great way to get the carbs in. Stick to the same number of scoops of powder for any event, but use a large bottle in the heat and use small bottles when it's cool. Keep it simple.
4.) I very rarely cramp, but in my experience cramping is a result of pushing beyond your limits and not drinking enough. If you cramp, be happy you've given it everything you've got and get some fluids in.
The table below shows a comparison of the main drink products I've come across and used for an extended period. They are all great products and do the job. Some of them are recovery based and some and energy based, but for endurance events I find any of these products will do the job. Over the course of 4 hours, I would drink 3 serves of energy and 1 serve recovery. The key factor here is to find a couple of flavours you like, ones that you can still stomach after 4 hours of exercise and alternate between those flavours. This is particularly important if you are going for longer than 8 hours. The table ranks the products based on price. I have calculated the price on the dollars you pay for 100 grams of CHO, so you can see very quickly which are the best value.
Here are a few notes on each product.
1.) Gatorade: Here just as a baseline for what you can get at the supermarket. Not a favourite amongst cyclists because of the sugar content, but better than nothing. Staminade has some magnesium so may be a better option than Gatorade.
2.) NutriScience Extend: An energy product that I really love. Good value and I love the Peach Iced tea flavour. This powered me to a World 24 hr MTB age group win.
3.) Endura: An energy product and used widely in all sorts of sports. I find the magnesium content too strong for events more than 3 hours long, but it is good value.
4.) NutriScience Refuel: A recovery product but great for a slug of carbs in a long race. Again I love this product for the great flavour and good value.
5.) Hammer Heed (Energy) and Perpetuem (Recovery): Hammer Nutrition are a big player in the US and are gaining a prominent position here in Oz. Their products work and they are priced well, not to mention you can buy jugs of the gel at very good prices. I love using the flasks to hold 5 gels, no messy wrappers. Just take a gulp from the flask and pop it back into your jersey pocket. My only complaint is their drink flavours are not all that great, but for me, if it works, I'll swallow it. That is until I get to 3am in a 24 and I just cant swallow it anymore.
6.) TORQ Energy and Recovery: TORQ are what I would call a premium product and as you can see you pay for it. Good flavours, full range of products and all the science and support to back it up. If money is no object, give it a go, but it's too rich for me.
7.) Optimiser (Recovery): A good product and available everywhere. It has been my staple recovery for many years (until I found NutriScience). Banana is my favourite flavour, chocolate is OK, stay away from the vanilla (urgh)
So there you go. It's NutriScience for me, with Hammer in close second. As an aside, NutriScience also have a terrific beetroot based product that is full of nitrates. I have found taking a serve of this 3 hours pre-race to have a benefit to my performance. It could just be a placebo effect as I have no empirical data to backup my claim, but it seems to have a positive impact on my results. I hate giving away my trade secret, but if you havent heard about nitrates before now, you soon will. Having written this post I just realised I have left out one of the biggest of them all which is Gu. My LBS has never stocked the drinks so I never raced on them. We've all benefitted from a few free gels they throw in at big events and they taste OK, but they are often very thick and they are messy to open. I prefer the Clif gels that have the little keeper that keeps the top of the wrapper connected to the main body of the package.
I hope this has been some help, there's probably lots more I could say, but you'd probably stop reading after a while and some things just take time to work out for yourself!
Disclosure: Hammer, Nutriscience and TORQ have in the past provided sample products to me for trial at a discounted rate or for free. I have then purchased these products at full rate for long term use.