More specific questions in the CX vs Road bike saga

slowpoke joe

Hi, I am new to this site, and while I have been riding a bike most of my life I am looking to get a bit more serious as I recently completed a 30 mile charity ride and loved the experience. My bile is a Fuji CX bike. I did replace the knobby tires with 32mm slicks and also had the 46/36 swapped for a 50/34. I am pretty sure the cassette is a 12-34 Tiagra. I bought the CX because it was one of two bikes in the shop that fit me and thought I might like the trail ability of it, but I really just do roads and that is what I want to pursue going forward. So what doesn't work for me? I spin out going down moderate hills. I am concerned that the 32mm tires are adding to a workload I am just working towards coping with anyway. I wouldn't mind a lower BB as well but that is not my top concern. I know I can re-gear the bike, but with the wider fork and seat stays that come on a CX, would I run into issues mounting a 25 or 28mm tire into a wider frame? I know they would fit but would the geometry get weird somehow? The wheels are 622-17 so as I understand I can safely put a 25mm or 28mm tire on it. I guess my end game is deciding what modifications would be effective in making the bike more road worthy, what modifications would have ill effects, and if I should just look at getting a suitable road bike instead. I was pretty much dropped by everyone in the 30 mile ride and that is on me, not the bike. That said I don't have lofty goals of being one of the fastest, but rather being able to keep up with the average dedicated cycling enthusiast that one finds in these organized rides. Again that is on me but I want to make sure my bike is not hindering my efforts to improve.
Any advice would be appreciated!

cougie

As you've pointed out it's more you than the bike.

Sure you can fit narrower tyres no problem and reduce the rolling resistance. Most road bikes are on 25mm now and 28 would probably be better but they don't fit most road bikes.

Personally I'd probably stay with what you have and know you'll be getting a harder workout on it.

If you get dropped on descents try to slip stream and keep as aero as possible. Or get a bigger gear.

N0bodyOfTheGoat

Is the cassette definitely 12-34 and not 11-34? If so, the latter could help with downhill speed, but many find speed gains by getting a good aero position and freewheeling with static pedals roughly parallel to the terrain. You might find a narrower range cassette will give a suitable low gear, but then give you smaller steps between gears to help lessen cadence changes between gears.

Can you improve your aero position, by lowering your stem on the steerer and placing it in the negative position, without discomfort? Being a CX bike, the stem might be slightly shorter at ~80/90mm, a longer one will stretch you out and make you more aero.

For 17mm internal rim width wheels, ~28mm tyres will be the sweet spot for comfort against aero drag, Some manufacturers make a nonsense of tyre sizes, for example 700x28 Continentals measure ~31mm wide on 17mm rims. Consider the tarmac quality you ride on and use that to judge pressures plus the total weight of you and everything you carry on the bike. That's ~90Kg for me and many roads are not in the best shape up in the South Downs, so I use ~70/85PSI front/rear.

Another factor could be the weight of you and the weight of your bike, if you tend to ride in hilly areas. Two years ago, I weighed ~95Kg without cycling kit and my only bike at the time (the Voodoo) weighed ~16Kg, the ~0.5 mile ~6% hill on the way home from work was a hard slog for ~3mins30secs. Now a hard slog on my Cube is holding ~275W average for 20mins.

Too tired to think of anything else, way past my normal bedtime!

slowpoke joe

Thanks for the replies and food for thought. I am carrying extra weight from my ideal for sure and want to lose about 13kg ( 30 lbs) - a benefit of riding more.