Originally Posted by
VegasTriker
Whatever you do, before buying the parts figure out just how it will affect the gear range. You can use the Sheldon Brown gear calculator
https://www.sheldonbrown.com/gear-calc.html to see exactly what gears you will end up with.
I looked up the current version of the of the Quick CX3 and see that it is 2X by 8. You can go up to an 11 speed cassette in the rear because 8 speed to 11 speed all use a 130 spacing for the dropouts. If you want to go with a larger low gear on the cassette you need a compatible RD. I did this when changing from SRAM 10 speed 11-36 to Shimano 10 speed RD a decade ago. The only modification I had to make was use a longer "b" screw. I used the derailleur Sheldon Brown recommended but he has since died and the information on a wide range rear is now gone from the website.
You are not the only one with the same idea. "Rear derailleur for 11-36 cassette with Shimano 105" Apparently this site will not let me direct you to the actual website but first link that comes up with Google is the one I was trying to show.
Thanks for the link. I'm going through the calculations now. This is very helpful.