Standard Rack + Free Radical
 

do they play well together? Specifically, I'd like a more stable option for my bike while my son is at the top range of weight for my Topeak Kiddie seat. I'd like a more stretched out bike while I wait until he gets to an age that I trust him to hang on to the stoker bars, and eventually upgrade to that.

Yes it can be done: I currently do this with a CoPilot seat on a rack with a Free rad. Just a couple caveats: 1. Your Free Rad storage space may be slightly reduced depending on the length and bulk of the child seat, and 2. You will also have to adjust the size of your snap deck. You can cut your current snap deck down or create a whole new custom deck. I did the latter and just used the old snap deck hardware.

Also, removing and installing the seat may require you to remove the V-racks. My CoPilot can only be installed by sliding it on the back of the rack, and there is no clearance without removing the v-racks first. Hence the CoPilot is a permanent part of my rig for the time being, but this is ok with me since a couple of my kids are still young.

OK, sounds good-- I was actually thinking about doing this without v-racks or any accessory. I just want the longer wheelbase for stability.