Caliper

Because if you are going 39t on the small ring, it makes good sense to bump up the big ring also. No sense in narrowing the gearing range when you can gain some downhill speed. Besides, 53/39 carbon cranksets aren't that expensive on Ebay.

noodle soup

they're a lot more expensive than a 39t ring.

Caliper

Sure, but you also get more so it's worth it.

noodle soup

At a cadence of 90, a 53x11 is 33.9 mph. A 52x11 is 33.3 mph.

Not much of a difference in speed, but a huge difference in cost.

Sy Reene

Thought I'd heard that (maybe just Campy?) that the shifting ramps on the rings are paired for efficient FD changes.. ie. the 53/39 ramps are paired optimally, 52/36 are paired optimally etc.. Any shifting smoothness downside to using rings mismatched from originally intended by the manufacturer?

Caliper

By the time you spin it up all the way, the gain is more like .8-.9mph though. I'd call that worthwhile. Hitting a new top speed PR always makes a ride.

noodle soup

My top speed PR is in the mid 50s, so gearing isn't going to change that.

Caliper

That's great if you live in the mountains I guess. Around here you're only getting to the mid/upper 30's by coasting. Getting faster means gearing.

woodcraft

Go for the 70t ring,

and watch the KOMs roll in!

redlude97

One reason would be the ramps won't line up correctly.

noodle soup

It won’t change a thing.

phillman5

I had a 53/39 on my older '88 bike, and when I got a new bike a few years ago it came with a 50/34. In Albuquerque we have rolling hills, and when you need to shift the front, thats usually too big of a jump so you need to ALSO shift the rear. With the 53/39 this was rarely the case. In Tucson I remember a racer that had something like a 53/48.

merlinextraligh

Angels, pin, dance

noodle soup

50x12 takes me near 40mph. I'm not strong enough for anything more on flatland.

georgiaboy

How long can you maintain approx 110 rpm?

DrIsotope

The day I spin out 42-10 on flat ground is the day I'll consider new gearing... because I'd have to be putting out +1,200W to do so. As I can currently sustain 1,200W for precisely zero seconds, I'd say my current gearing is adequate.

noodle soup

110 is a reasonably comfortable high cadence. In a real sprint, it can go well over 125.

georgiaboy

You have convinced me. Can you tell me who makes a 10 tooth cog or a cassette so I can try the 42 x 10 gearing?

DrIsotope

SRAM. They're not uncommon.

georgiaboy

Yeah sprinter can do it for 300 meters which isn’t helpful for any serious riding. I notice you didn’t state the duration. You don’t need to tell me I don’t want to know, anymore.

noodle soup

Some people here talk about 110 being a high cadence, but it’s really no big deal.

spend some time in the Rockies on a FG bike, and you’ll learn how to spin a high cadence.

georgiaboy

Why bust my ass on a FG in the Rockies when I could just log into BF’s and say anything I want?

noodle soup

some people here actually believe this.

They can't spin along at 110 rpms, but think they can push a huge gear.

jadocs

This is a very interesting thread. Found it because I think I need to go the opposite direction. I'm currently running 50/34 rings with a 11-30 cassette which I think is not enough. I think swapping out my rings for a 52/36 and keeping the 11-30 would be perfect for me. I'm constantly in a pretty high gear, and I have never shifted out of the big ring unless I am doing some steep sustained climbing. This is a typical weekly solo effort on the flat with three complete stops factored in (stop signs and lights), showing I spent most of the time in the 12. It's a steady high effort pace so I am not surging or sprinting. If I were to sprint, I would need more than 50-11 as I have been in sprints and tried to shift only to find out I was already in the 11 and there was nothing more...and I regularly spin out going downhill. My FTP is calculated by real one hour efforts on the road, not 20min tests on a trainer. I'm not a lightweight either over 50, and at 206lbs. The power pic is from a separate ride so I can turn the gear. I'm not a "spinner" when it comes to sustained power output on the flats. If I am sprinting I will be 115+.

Rides4Beer

Now that I have almost 800 miles on the new bike (50-34 & 11/34), I can say that I def made the right choice. Have done several rides with over 10,000ft of climbing and it was great having the extra gear. Also have no trouble keeping up with the A group rides. Sure, I spin out going downhill, but at that point I'm doing 40+mph and gravity can take over from there.