If you really want to do these races then my advice to you from personal experience is to first do all the mary jane thrill rides there are three of them. After doing all three you will unlock webswing 7 a passive ability which will let you webswing faster and is crucial for the races.
You must learn and master all of the controls and learn how the camera works and readjusts itself. The main moves you will need to master are webzip boosting and and webswinging. To webzip press right trigger now to webzip boost press left trigger right after right trigger this is the fastest way to get from point a to point b but it is not going to be used in every situation.
Some times you will need to brake when webziping and webzip
boosting this takes time to master but will come with time the races teach you how to control your distances. Webswinging and webswing boosting is very important to master press and hold right trigger to begin your swing and then press left trigger and various points in your swing to get different results.
Example to quickly desend immediatly webswing boost when you begin your swing and let go this will drop you like a rock. Boost at the top of your swing to gain height,if you need even more height start holding a as soon as you go into your swing and webswing boost at the top and let go of a and you will soar into the sky,lastly to shoot forward quickly webswing boost in the middle of your swing no a button.
Wall running and wall run jumping is the hardest thing to learn and will take time to get used to. The biggest thing is to stop your momentem by pressing a and then hold left trigger and b and hold towards wall to start wall running. The camera will go insane if you mess with spiderman to much during wall running so this takes time to get used to.
Wall run jumping is the hardest checkpoints besides loops and orbits to trigger (more on that later) you must start your wall run and then start spamming the a button while within the checkpoint so fustrating to get this sometimes again practice practice practice.
Loops are a nightmare they require you to attach your web within the checkpoint and loop vertically as straight as possible then launching yourself from the loop into the next general direction of the next checkpoint.Absolutly critical for race 39 and 47. Gold wont happen unless you master the loops or get luckly with a insane run.
Orbits are hard as well but not as picky as the loops you have to get used to the camera catching up with you as you go around this things again no advice except practice you will see these on race 39 for the first time.
The reason people find these races scary is because there are no real videos on the net yet and the paths the developers want you to take isnt always clear therefore people just quit because they dont know how to do them. There is a set path to take and moves to do that make the races possible. You must memorize the path first then you will start knocking your times down then it comes down to executing as perfectly as possible.
More tips which are critcal to success. When wall running you will lose speed eventually when this happens start pressing the a button while wall running this will make you go at top speed critical for some races. Charge wall jumping you will need this to gold race 15 i think its 15. You will hold a from a webcrawl and not press anything else you will shoot in the opposite direction quickly. It takes time to learn how the camera auto adjusts and is really important to learn how to deal with.
You must always make mini adjustments to spiderman as you are moving through the air example you do a webzip boost and you will notice that you will pull in one direction or the other you must contantly readjust while moving in the air again practice.Always jump after webziping or boosting if you need to get somewhere fast again this all depends and the situation.
People debate which suit to use i think the red suit is the best for the races as its more stable that the black i have heard. For races like 33 which you must be extremely accurate this is important.
If you need help with a particular race let me know and i will try to help although everything i learned i learned from the best spiderman 3 player in the world which im not sure if he wants his name mentioned or not so i wont so but might edit later if he doesnt mind. Videos might be made in the future. Dont give up and persist and you will do these races try to go in order and dont stop its nice to unlock all three acheivements in one go like i did dont move to the next race till you gold the previous one.
Good luck again this achievement isnt impossible just very hard.