I love this thread! I finally feel like there is a good justification for me to have a 53/39 aside from wanting to be a “big boy” or as some folks might say, I’m over compensating for something. 
In general the steepest climb’s I find in my area are around 10% and a 39-28 is perfectly fine for me in those situations, especially since they are never very long. Were I heading to the Alps I might swap it out with a smaller chainring and bigger cassette for those longer sustained climbs.
I hear everywhere that they are quite a bit faster. (like 10 watts or something, depending who you ask) What I always wondered: are they any more fragile? Like you hit a tiny pothole and poof, ya walking. Or do they wear out or something?
They’re actually more durable, just easier to goof up the install. Latex is thicker than Butyl for an equal weight and are tougher to puncture because of a thicker sidewall. Again, the speed savings aren’t huge but ride quality is definitely smoother and less buzzy
Sorry for derail, back to Drivetrains or this just becomes the Marginal Gains thread lol
I race gravel on latex tubes. So there is that.
One thing about latex tubes, though, is that the tube will conform to every nook an cranny in the wheel and rim. If you’ve got a little 4mm or 5mm slice in your sidewall you’ll find a little pink translucent bubble poking out of it after you inflate the tire.
More importantly, if there is a way for a latex tube to inflate into your spoke holes you’ll have a lot of problems with flats.
But generally I’d say they’re not more or less robust than butyl tubes. But they are the fastest rolling pneumatic setup you can put on your bike. By quite a bit. One of the few things that you’ll be able to see pretty much every time even with a +/- 1.5% power meter.
call it the big dog 
In all honesty it does make a difference for those of us 80rpm natural spinners on Wed night worlds where there is a 6 mile tailwind section where we average 25-28mph and a mile or two often above 30mph. Not far from here there is a more serious p12 ride for the big boys where they average 35+mph on a good stretch road.
Thanks for the info folks! I think I’m gonna give those latex tubes a whirl.
A bit more on topic: My bike shipped with 52-36 (and a 11-30 cassette). For me that’s a bit too big. Most of the time I ride somewhere mid cassette, while my 11t cog is brand spanking new. I think going forward I’ll swap the front to 48-32 and keep the cassette. That should give me a nice range in the big ring for the flattest of flat lands where I live, and a nice low gear for the holidays in the mountains (and the occasional gale force headwind).
We need a minimal gains thread, where we can discuss the 3 fastest items.
bike - systemsix, cervelo s5 and so on
lube - wax, … , …
helmet -
Are you somehow figuring out the optimal cassette for your actual chainline geometry, calculated to minimize cross chain bend in your most used gears with this tool, or just seeing possible speeds per gearing and strictly determining the best range for you?
I just changed from 11-32 to 11-26 since it’s super flat here, I figured smoothing out the range in the middle gears I use most was a good idea, but have wondered if my chainline on those most used gears is as straight as it should be for my typical use. I considered trying to make use of gearing data in my rides to see if the data suggested any particular gearing combo for me but in the end just guessed, because it was starting to feel a bit like the Julia Roberts math-ing meme.
If you have a di2 bike with Bluetooth or sram axs it will tell you on the sram app time in gears
Thanks, I’ll check out the app, I have red etap so hopefully the data is compatible
Edit: doesn’t seem to be working w non axs etap. I do have gearing data in wko & garmin so I’ll need to dig around to see if a similar summary is available there.
I’m running a Rotor 54T outer and Shimano 38T inner chainring with a SRAM 11-26 cassette on my Speed Concept. That way I have a 16T sprocket on the back (the 17-15 jump would feel too heavy even if my cadence was still ok), I can still get over the hills in the triathlons I compete in, but at my racing speeds in the 54T, my chain line is the straightest at my preferred cadance.
They should have used the same chain. And the chains should have been prepared with the same cleaning and lube proces.
The sram 1x chain is notoriously inefficient.
Thanks for posting this - and I really like that the numbers are for a realistic ‘normal person’ speed - 18mph, rather than the much higher speeds (ie 40/50 kph) that are quoted for aero gains.
What site is this from?
Also, as I understand it, the CRR can be thought of as the grade in % of a hill, so a CRR of .003 is likely constantly riding up a .003% grade (per tire, so .006% for two).
