From personal experience, I find that creatine gives me worse arm pump when riding downhill tracks. This muscle pump is evident when training any muscle group whilst using creatine.
Thats because it is a supplement developed mainly for the body building scene.
What Creatine does is cause all your muscular cells to retain water.
Fist myth...This isn't water retention like people think of when talking about Steroids. That is water retention under the skin.
Hydrated muscle cells (what creatine promotes) are essentially a more anabolic environment, this combined with the fact that the chemistry involved in the cells with the use of creatine (to do with phosphate changes/drop offs in the ATP energy cycle...can't be arsed to go into it) means that you get a more swollen look to your muscles when saturated with creatine.
It increases "pump" because of this....which is not what you want for riding.
The only cyclists likely to benefit from Creatine are those that have a lot of explosive action needed over a short burst e.g 4x riders or short duration indoor velodrome riders.
DH riders may benefit getting out of the gate too.
Anyone doing any endurance/distance riding should steer clear of creatine. It makes you prone to dehydration which can cause severe cramps of your muscles.....and what is a muscle that gets worked hardest other than your quads when cycling distances....YOUR HEART. This is also why it is important to keep well hydrate when supplementing with creatine and to avoid alchohol (because it dehydrates you and puts a strain on your liver which is already under strain processing the creatine you are chucking down your throat each day).
If you are a 4x rider/ velodrome then Creatine may very well help you.
One thing I have found with creatine is it is only effective for a short duration i.e
4 weeks or so. It is good for getting over a hurdle/low spot in your training sometime.
But that said it can cause low spot as you need to cycle it and when you come off it you can often feel lethargic.
It seems to be less effective each cycle you do too....I Havn't used it in years and I may very well do some this summer and see how effective it is after a huge lay off....I remember my first trial of the supplement gave some pretty decent results.
There is many types of creatine on the market,
a lot of it nearly all of it is just market hype and bull s**t.
What is for certain is timing and nutrition to make your body "up take" it is essential.
An insulin spike whilst ingesting it makes it a much more effective supplement which is where some of the over marketed very expensive tubs actually work well as you are paying for an expensive tub of sugar with the creatine you are buying which gives you that insulin spike....expensive sugar though "Muscle Tech Cell Tech anyone"

.....Rokin and Strafer will get that

If you want to use it and get results from it then the best bet on a budget is to get a decent microganised creatine and take it with a big glass of sugary drink like grape juice straight after a workout. Preferably prior to your protein shake/recovery meal etc.
If you have cash then the best stuff on the market in my opinion is made by a complany called SANS and the product is called V12 turbo. It's a Di and Tri creatine malate salt solution mixed with some other chemicals that aid in transportation (uptake into the muscle cells). Use that stuff mixed with grape juice and you get some serious SHORT TERM size and strength gains.
Paul