Advice needed on road wheels Giant TCX

[F. Scotty]

Hi all…some advice would be greatly appreciated as I am fairly new to cycling,only been riding about a year.I have a giant TCX(my precious),currently has Ultegra 11 speed 50/34 with 11/32 cassette at the back. I have Maxxis Rambler 40’s on it as we’re on a farm and I ride it mostly on district roads and then on and off the tar. It’s great and I love riding it. Next year though I would like to get more competitive racing road and gravel,my question,especially for those who have experience with this,is to what extent would the fatter tyres slow you down in a road race? Would it be better to get another set of wheels with road specific tyres? I have done some research on the rolling resistance etc and yes they are faster but I’d also just like to hear from those that perhaps have 1 bike with 2 sets or just ride their one bike and maybe have a gravel tire that’s suited to both gravel and road?(if that’s possible as I want to race both). Thanks guys!

[El Duderino]

Following.

I recently sold my road bike and bought a gravel bike. The weight difference combined with the heavier and wider gravel tires equate to about 1.5 to 2 kms/hr difference in speed on the road. GB is noticeably slower. 

Am also considering a second wheelset for road.