What makes coasters bumpy?

Sorry if this has already been asked, I did a quick search and nothing came up.

Anyway, I was wondering, what exactly makes coasters bumpy. Specifically a coaster like Magnum, which used to seem really smooth, but recently feels bumpy. I've heard that it has something to do with the wheels, but I don't exactly understand what makes it bumpy? Thanks!

Apart from simple wear and tear, the most common cause is the weather, more specifically the ambient temperature. When the air is warm, both the wheels on the train as well as the track expand ever so slightly, resulting in a more consistent connection between the wheels and the track. When its cold, both of those surfaces contract so the train bounces along the circuit. Upstop wheels or pads that are a little bit loose also contribute to the train loosing contact with the track. This is why Dragster has more frequent rollbacks in the AM.

Magnum really hasn't changed. The biggest variation on that ride is the condition of the wheels. They vary a great deal.

Over time I'm sure the steel aging plays a part too. I seem to remember something about them changing sections of the Magnum rails, but I can't remember when. I've often heard that as many B&M coasters age they develop certain rough spots, which seems like it would be related to the steel rails.

For me the middle of the car, not over a wheel is much smoother.

I think that once you ride Millennium Force or other newer, smoother coasters, your perception of how "rough" older coasters are changes quite a bit.

Magnum still feels the same to me as it did in 1993.

TroikaX3 said:

What makes coasters bumpy?

Being a Vekoma. ;)

I noticed this past Sunday while waiting for Magnum that the black train looked like it had new wheels as it was coming into the station. We rode in the black train in the back and it was very smooth and didn't slam us up and down like the other 20 times we have rode it this year. I have noticed that Millennium and Dragster both seem to have a lot of vibrations this year, other people have commented on it after coming into the unload station. Almost feels like flat spots on the wheels or something.

Vibration on the Intamin coasters, in my experience, seems to come from loose springs (or whatever keeps the wheels pressed on the track). If you sit in the back, you can see lateral shimmy of the cars in front of you. B&M's do this too, the worst of which is Hulk at IOA.

The ride manufacturer and design affect the ride's smooth/roughness, more specifically, the wheel configuration. The Road wheel, up stop wheel, and guide wheels on Intamin and B&M coasters fit perfectly on the coaster rail. This causes less bumps and jerks throughout the ride. Hence why Dragster, Maverick, Millennium Force, Raptor, are smoother. (This doesn't explain Mantis. Mantis just hurts because you stand up.)

On the contrary, the wheel configuration for coaster designed by Arrow Dynamics and Wooden Coaster manufacturers are rougher because the coaster 's road wheel, guide wheel, and up stop wheels do not fit snugly around the coaster rail. Hence why we think Magnum, Corkscrew, Mean Streak, Mine Ride, and Gemini are rougher. You can see this on Magnum when train leaves the station and rolls over the midway on to the lift. You will notice the Road wheel and some of the guide wheels are moving on the rails, but the up stop wheels are not moving because of the small gap.

They take an ax at the beginning of each season and beat the hell out of the track