2nd set of decent Wheels (not always expensive) !
good road Tires (700x25) !
11x25 cassette,, using your 46/30 chainrings, will give a good road gear range for anything but the longest (3+ miles) steepest (10-12+ %) climbs
work to get comfortable with a cadence of 80 to 90 with the goal to be comfy at 90 to 100+
lotsa riding... working for cadence and efficiency - the power will come as you ride more and get more fluid and efficient.
if you averaged 16, the new wheelset, for road, might get you to 20/21 mph
you will still get shelled, if the group averages 24 mph, even on a flat river ride. But it will happen later in the ride.
you need to develop roadie fitness, which includes a tolerance to frequent suffering.
learn how to ride on a wheel, in a group, safely... river 'trails' have their own dangers, so be aware when at speed.
learn how to look beyond the riders in front of you, anticipate what is coming - DOn;t stare at the wheel in front of you or the back of the rider - look ahead.
until you become really skilled - NEVER EVER overlap wheels with the rider in front of you. starting at about 1 wheel length distance behind the rider in front of you, is a good distance to ride at for a while - IF you keep your attention forward and alert. If that feels too close, add a bit more distance.
try not to hit your brakes except for real needs like tight corners - learn to moderate pedal pressure or cadence to maintain a riding gap - learn/develop 'soft pedaling'
working on when to be aero and when to relax
roadie bike fit and posture is different from off-road
if you need to learn about gearing - a good gearing chart helps (when you understand the basics of gearing and use) - this one is good
Bicycle Gear Calculator
set it to 'mph', set your chainrings by sliding multiple rings along the range
wheel/tire size for 700c in the dropdown is something '28' like "28/25-622" (the number after slash is tire width), pick a cassette range, like 11/11-25 which is 11 speed 11-25 cassette... cadence defaults to 90 (but you can change to see the effect)... gear inches is the 'gear' - IE your 46 chainring using the 15 cog is an 81 inch gear, which at 90 cadence will put you at 22 mph (using a 25mm tire).
everything the same except being in the smallest rear cog, the 11, would have you at 30 mph...
get some well fitting kit. - multiple items, one pr of everything is no where... it doesn't need to be expensive, it just needs to fit.
if you're trying to do this with 'flat' pedals, I recommend that you start working on riding with some variation of clipless - mtb type SPD, eggbeaters, etc are a good option.
there's so much... too much for a post
it's out there for you to learn.
enjoy - it will come together with education, work and perseverance
Ride On
Yuri
EDIT: BTW, that
Cannondale Topstone Carbon Ultra RX 2 looks like a very fine bike, and with road wheels will be right in there as a top road machine. Light and fast. If you need to get more aero, bend your elbows more... ride in the drops... cheap and very effective... not always easy to do...