Hi,

I have a road racing bike for a year now.
I was messing around on my own with it or with tourer friends (I was the guy without any bag or rack that had the others carry its lunch ).
Anyway, I wanted to take things more seriously on a performance side and joined a club.
My condition slightly improved and my considerations towards gears use changed a little.

My bike came with compact crankset (50/34) and a 10-speed 12-27 cassette.
In that set-up it was pretty straightforward: 50 for flat, downhill, 34 for climbs. Indeed the 34 is way too small to use it for ride on the flat to use it for "supple" pedaling (you need to be riding at 100rpm on the 34x14 to reach 30kmh).
And my training roads are mostly flat so I really felt the 50/34 was not for me.
As I did not want to set-up my front derailleur, I only replaced the 34 ring by a 38 ring and the cassette by a 11-25 one.
The reason for the cassette change was that I consider I can cross-chain as much as I want except for the two extremes (small/small and big/big), so having a cassette starting at 11 allowed me to have a 38x12 fastest gear on the small ring which makes it very usable on the flat.

Still, I still have no trouble whatsoever in the little climbs I do, and I feel an extra speed might be welcome So I am considering moving to a real road crankset 53-39 and 12-23 cassette for I really like tight cassettes.

Considering the toughest climb I know in my region is easily climbable with my current 38x21, I should be able to go through with it on 39x23 and I would be able to have simultaneously a tighter cassette, and higher gears for those good times.

Does that seem to make sense? or is it suicidal?
I would of course keep all my stuff, and would be happy to mount the compact set for a ride in mountains and so.

Are you asking if we know better what gearing is most appropriate for your terrain and fitness than you do?

Seems to be. Going to wider gearing can be a bit confusing since you wouldn't know the best low gear to get. But going to tighter gearing, you already know what you need.

A 53x12 top gear is less aggressive than a 50x11. Not that gearing has anything to do with "extra speed". Personally, after rigorous review of all available data, slap on a 12-21 corn cob, leave your current crank alone, and ride it like you stole it.

By the way 100 rpm is quite desirable. Not entirely necessary but a worthwhile goal. 95 might be considered ideal if you can train yourself to do it comfortably. Relatively high cadence makes the use of a variety of gearing solutions more acceptable.

53x12 < 50x11 true, but maybe OP means that having 53 as big ring means having a tad more aggressive gearing overall, regardless of that one extreme gear.

1 change at a time - either go for road cranks OR a tighter cassette and see how that goes. you may find that the 39-27 or 34-23 is a useful gearing.

personally I would prefer a bigger chainring. I think compacts should be 50/36 rather than 50/34. You may be able to find a bigger ring for your current cranks and go to 50/38

Except that isn't any more aggressive. With a tightly spaced cassette, the only meaningful difference between a 50 and 53 is at the ends. Theoretically, a 50/34 with a 12-21 gives no gear overlap, and linear shifting inside a ring. When you change rings, yes you will have to bang off five steps on the cassette, but you would have very tight gear increments over the full range.

Regardless of the the theoretical, in actual use, I have ridden 53/39 with 12-25, 50/34 with 12-28, 50/36 with 12-25 & 11-26, 46T single x 12-25, and single speed 47x16. At speeds under 30 mph, there is no appreciable speed difference among any of those combinations. With a 47x18, that drops to 27 mph.

While there's nothing wrong with the 53-39 and the 12-23 cassette, let alone suicidal, it's almost pointless. Unless you face some specific circumstances where you need the 53x12. Speaking personally, I'm not any faster in my 53x11 gear than I am in 53x15. Maybe if you're a brute or do a lot of drafting at around 30mph but otherwise it's way down the priority list.

OP...unless you need the 53 for descending...leave the front at 50-38. Btw, that is what I converted my Campy UT compact to...50-38.
Then experiment in back with what you need. Bigger cassette for climbing. Smaller for tighter cog spacing to tune cadence and 11t for higher
speed if you need it.

I would think 50/38 would be a nice compromise.

It really is a great combo for an amateur. 50/34 puts too big a hole in gearing in front. 34t small ring has no legs for running on the flats and 38t makes the small ring much more usable.

53/39 and 11/23 cassette. The 53/11 is for downhills and low cadence intervals on flatter terrain. However, my suggestion is to master higher cadence higher power efforts. If you are comfortable at high cadence and high power now then switching to the 53/39 is fine. If you struggle with higher cadence after one year of cycling, you need more work on it and stick with the compact. Once you change to the 53/39, you may begin to self select bigger gears and lower cadence. That is not bad or wrong but it may be too early for you considering your experience.

We are all different and only you know what works for you and your terrain.

Yeah, you guys are probably right.

The idea behind changing both together was while moving from 50/38 & 11-25 to 53-39 & 12-23, I would be able to keep the same chain (the wear on my chain and the cogs is still minimal for now so the whole thing of mixing new cassette with used chain is not yet an issue, but that was just a practical issue.

What you say does make a lot of sense. I will continue like this, possibly considering that 12-23 cassette (I really like the tight set-up of that cassette)....

I will think about the 53-39 later... (though, all reasonable arguments put aside, 53-39 look so much classier than 50-38 not to mention 50-34...)

The only reason to ever consider a 53t is if you need the gear inches if you are a 1000w rider for sprinting or...for descents. You can go dam fast downhill hill with 50-12 or even 50-11 if you must and therefore unless racing, I see no purpose for a 53t big ring. Vast majority of average cyclists are better off with a compact. Some don't need the climbing inches either btw and why a tighter spaced crank in front like 50-38 or 50-36 makes a lot more sense. Its basically a baby full size crank. To me with 10 or 11 cogs in back, a 50-38 with 28 or 29-12 or 29-11 makes a lot of sense. If you don't descend above 35 mph like me for example, then even a 50-38 29-13 is a great combo...tight gear spacing with excellent climbing inches and both rings very usable in front.