Parts are used for bike upgrades to give you more control and power. But Trials Frontier also has a part upgrade system, that lets you fuse three lower tier parts into one upper tier part. The better the bike, the higher quality parts you'll need, so fusing parts together for upgrading bikes becomes a sort of game within the game.
Certain tracks require you have a specific bike to enter, so upgrading and finding blueprints becomes a major factor in your success.
Even more to do
Amidst all of the racing and upgrading, certain quest characters will develop new technologies for you. One of them is a slot machine that gives you a quest, then, once completed, you get to spin again to win money, blueprints and more. You can only use the slot machine once an hour, but it's just another fun extra that adds variety to the game.
I've written before, and Trials Frontier uses a model I don't like, but surprisingly find bearable.
In this game you have a limited amount of fuel for racing. Each track has a fuel requirement to enter, so when you run out of fuel, you'll either have to pay real money or wait for it to recharge.
I've found that I can get about six or seven races in before the game stops me from playing, but that doesn't include restarts within a race. So even though there's a limit, you can restart over and over to get that perfect run without using additional fuel.
Though I don't like that it limits my playtime, I'm usually fine with what the game gives me in a sitting. Fortunately, you never have to wait too long for your fuel tanks to fill up, but it's something to note before downloading this game.
Trials Frontier is not only a great iOS game, but a worthy new edition to a long-running and popular 2D racing franchise. The physics-based gameplay is excellent and there is so much here to explore that you'll almost never run out of stuff to do.
Not only is there a ton of racing content, but you also have upgrades, new bikes, and new areas of the map to keep you busy. This game has a lot of replay value, and I've found that I keep launching the game to go for that next upgrade and try my luck "one more time" at the slot machine.
With all that said, it is a freemium title that limits your playtime. So, while I recommend this game wholeheartedly based on gameplay and content, you'll have to decide if the wait times will bother you too much to enjoy Trials Frontier. In my experience, the the vast world to explore and great racing action are worth putting the game down a little while to recharge.