Kickup angles throughout time

[Saito]

Just out of curiosity, how/why did manufacturers decide or settle on particular kickup angles for their buggies? The RC10 started with 30 degrees but its first major rival, the Ultima, only had 20. The JRX2 also ran a 20 but the follow up JRX-Pro was back up to 30. Was there a benefit ether way or something that each manufacturer had in mind or was trying to achieve when picking the kickup angle? Does it significantly affect the driving characteristics, i.e. does and Ultima drive very differently than an RC10, etc.?

[GoMachV]

Here is a quote from Terry that should help a little. Remember that the kickup works with the caster blocks to set the caster. Even though the rc10 had 30⁰ of kickup, the caster blocks took out something like 15⁰ of that (for the reasoning, see Terry's quote below). The Ultima and Losi on the other hand use blocks that don't change the caster, so it remains at the angle of the kickup.

Now assuming you change the caster blocks so the caster is kept the same when you change kickup, less kickup will give you more steering and the chassis will dive less under braking. It will also give more on-power steering. Increasing kickup does the opposite, but is also much better over bumps and jumps.

[Chewbacca]

Check this out:

https://www.rc10talk.com/viewtopic.php?f=35&t=3