I'm looking for a way to covert my sram red etap 2x 11 speed group to a 1x system to get lowest possible gearing for gravel riding and still be able to use for road riding. Right now I have a 34 small chainring and 36 lowest gear on my cassette with the wifli and a wolftooth roadlink. It's not great as I have chain droop in my 11 and 13 tooth. I try not to cross chain this combo. More importantly, I've joined a gravel group and my lowest gear isn't low enough for me.

What I hope to do (other than get a new bike which isn't easy right now) is to pull the battery on my front derailleur so I can't accidentally shift the FD, get a 38? chain ring and an 11-42 cassette. I hope this will be adequate for faster road sections and low enough for steep dirt hills. My 32 knobby tires work fine for what I'm doing.

One thing I don't know is how to measure the chain for a 1x setup so help with that would be appreciated. Also any feedback or other ideas please.

I can’t comment to specifics of etap or chain wrap but I’ve played with those ratios.

38x42 is a great climbing gear. But 38x11 is pretty lousy above about 16mph.

I have settled on a 40x10-42.

Still a great climbing gear and an extremely adequate fast gear. I rarely spin it out. I have a second Sram cassette with a wolf tooth with a 44 (so 10-44) I like better. This is all 11sp.

If you don’t want a new driver, a. 42 or 44 with 11-46 is probably what you need. This is definitely into new derailleur territory, but I know Sram mechanical 11sp derailleurs can do that (force or rival) unofficially.

1X does not by itself get you lower gearing as often time the ring is typically bigger than the 34 you have now, so as to keep some usefulness for taller gears. 1X also usually sees a big pancake 11-50 type cassette, which you probably cannot install and use with your rear derailer. Thus I'd look into changing the crank to a 30/46. That's a common setup on gravel bikes. Not sure the SRAM will work, but start there and see.

There is a lot to unpack. I’m not sure where you are on your cycling journey as to what gears you can push or if you can eventually get strong enough to push. I’m far enough past my prime to understand the process of gear chasing.

A 46-30 is a good suggestion, but if your current 34-36 doesn’t work, a 30-36 may not be low enough either.

I see you have a mtb. If you can ride the same climbs on that bike you can get an idea where your lowest needs to be.

The sad truth is 1x or 2x will not get you the widest possible range. My brother runs a 44-32-22 mtb crank with an 11-32 cassette. He goes from less than .7:1 to 4:1.

I’m not professing you go to a triple, but if you need less than .8:1 and a 4:1, there are not a lot of options.

John

Edit added: You have obviously blown the RD capacity, or the chain is too long. If a 46-30 is low enough, you might want to see if you can replace the 46t with a 40t. Probably not within spec, but it will help with chain wrap.

Lots of ideas here for me to digest - and put into my spreadsheet to see the gearing ratios. I appreciate the feedback about less-than-ideal road gearing and spinning out at 16mph would be bummer. Yes, I'm gear chasing due to getting old. 😫 But I'm not throwing in the towel yet. Riding the mtb is an idea too though not as much fun (plus the thing is a 35 pound tank). I definitely blew my RD capacity as it is right now.

Would be great to find a long cage RD retrofit that would work with my current wifli derailleur ...

If you go from 2x to 1x then you will loose the range of gearing you might need to ride multiple surfaces and conditions.

You won't cheaply change it to 1x and have the gearing range for both types of riding IMO,

Compare the gearing ratios.
Currently: 34F 36R = 34/36 = 0.94

The 1x: 38F 42R = 0.90. That's only 4.5% easier, about a half shift (or even less than a half shift for a 1x drive train?)

You'll want at least 15% easier to make it worth the trouble, I think. Near a 0.80 ratio (or even lower?) That would be a 34F 42R. But then you are spinning out on the flats pretty easily. (I've had my Di2 battery run down, and rode 20 miles of hills and flats in the 34F 11-32R. Not optimal!)

Maybe consider a bigger cassette than a 42.

Looking at suggestions I think the 30-46 would work well ... It's still a 16 tooth jump, but not sure what the issue would be re: etap FD??? I'm far from an expert on bike mechanics though I do try to do all my own work. Would I need to move the FD down? Any other issues I don't know about?

low gear would be: 0.83
high gear: 4.18 (close to my current 50, 12 and good enough)

Calculator!
I used Mike Sherman's Gear Calculator for years, then the site went away. It's back on github, with slight format changes, and improvements -- It can do 13 sprockets now. (Rotor has 13 speed cassettes!?)
https://mike-sherman.github.io/shift/

Set the cassette sprocket sizes, then the next tab is three chainrings -- for a 1x, you can try three different choices and compare them together.

This chart shows a range of rpm for each gearing combination. For road riding, 80-100 is useful, for gravel, maybe try 60-80? For steep climbing, I look at 40-60.

The chart looks like this. Each chainring in a different color. Seeing the overlaps and the mph change for each shift is helpful.
The chart updates on the fly as you change drivetrain settings!

I picked a 11-52 12 speed, and set 3 different chainrings. All the gears can be edited too.


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

A few years ago, I was doing fast-for-me club rides, and made a cassette that had very close shifting from 18-24 mph, where I needed it. It was a 14-32, built from a 11-32 and a junior racing cassette. It worked great for those rides.
I would spin out at 28-29 mph, but that was never a problem. I just coasted on downhills faster than that.

So, you might be fine with a top gear that's usable to 25 mph or so, and has very low climbing gears. Above that speed, spin fast, or coast.

This is it. Advantages: a straight block to 25 mph. Disadvantages: The 34 tops out around 17 mph, instead of 21 mph, so I shifted the front a lot. Di2 makes that easy. And I often shifted two or three gears in the 34 ring -- too close together!
I'm back to a 11-32 now, with easier paced groups.
Anyway, this is an example of how the gear calculator is useful.

Whatever direction you go, you need to be “closer” to you RD max capacity. You don’t want the chain to go completely without any tension. Sagging in the 11t and 13t is a recipe for disaster if you inadvertently shift there.

If you want to do this correctly, you’ll need to buy the right components that will give you 40t+ capacity. Not sure what SRAM offers, but before you start spending money, you need to do it right.

Having to run a RoadLink is probably not everyone’s preference, but if the shifting is fine with your 50-34/11-36, I would think it would be similar with a 46-30.

John

On the calculator, you can click the Save tab, then the Save button to generate a URL to bookmark.
Here's your proposed setup:
30-46 front, and 11-36 rear at 70 to 85 rpm -- is that good cadence for your gravel riding?

And see the Speed tab: Try 45 rpm to see the mph for your lowest gear at this lowest "sortof reasonable" cadence: 2.9 mph. It's 3.9 mph at 60 rpm.

Tradeoffs:
the 30 chainring only goes to about 15-17 mph. good enough.
the big chainring has fairly large jumps between shifts in the 15-20 mph range. But that's typical of 11-36 wide range cassettes.

Quite low gearing--good. Low enough? It depends just how steep and rough your gravel roads get.

Converting 2x to 1x and getting the "lowest possible gearing for gravel riding and still be able to use for road riding." is contradictory. If you want the lowest gearing and also a bike that has high enough gearing for good road riding, the answer is 2X with an appropriate rear derailler and cassette, period. 1X compromises either low or high (generally high) and is good for MTB and other riding where a high gear is not needed.

What do you have against 2x for the riding you want to do? I don't disagree that 1x is great for some things, but not for the two criteria you mention: lowest possible gearing for gravel and good for general road riding. 2x will not only give you lower gear, but is much more versitile.

best I can tell the red derailler 11 speed is maxed out at 32 max rear cog, so at 36 you are really pushing it. could not find any specs on chain wrap

the 12 speed is 36 max test and 39 teeth of chain wrap.

I think to get any lower you are going to need a different group

SRAM RED eTap AXS Rear Derailleur - 12-Speed, Medium Cage, 36t Max, Black, D1

One thing to think about: Mr. Rides of Japan is a 1x fan but with the short chainstays on his Emonda the noise of of the extreme chain angles drove him to make his Emonda to 2x.

This will be a temporary modification to get me through a few month of wait time for components. In the meantime I really want to enjoy my Sunday gravel rides without having to walk or fry my legs completely. I've been riding this less-than-ideal setup for 3 years now, and yes, it's not fun when I forget to stay out of small/small cogs. Unpleasant enough that I remember not to do it any more. I'm looking at going with AXS and also looking for another bike. Another bike is likely 6 months out.

Great video! Another can of worms and thread, I suppose. My bike is small and I have all that noise he talks about. I spent a lot of time with the bike on the stand trying to figure our what was out of alignment and found out it was simply noise from the chain due to the angle. And I have a 2x. Hate to think a 1x will be that much noisier for me. Good reality check. That guy must have a boatload of cash to buy all those components to experiment with.

My original plan - before posting this - was to go with wider tires and I would have to remove the FD as that battery limits me to 32 tires. But I don't really need wider tires and I have nothing at all against staying with a 2x.

I have a 1x11, running 50T and 10-42. Great for roads, but climbing with a 50/42, while quiet, only makes my loud breathing more noticeable.

So, I looked into differences, and simply bought a 46T and a 42T front chainring. I swap depending on where I'm going to be riding.

That being said, 42/42, while 1:1, is simply not the same as a 34/34, also 1:1.

I think if a 38F/42R is not enough for you, you may need an MTB crankset and a clutched RD.
Perhaps a compact crankset would do the trick, get you down to 34T front.

I simply, as a road-only guy (so far), cannot imagine riding a 34/42 up a hill.
I'm guessing <2 mph but spinning smoothly. I'd fall over.
I did once get passed, easily, by a Pugsley running something like 22F/34R. He was grinning.

I’m not sure about this claim. There are some frictional losses but I’m not buying that it’s different.

I'd sell off the etap 11 parts and move on to axs 12. I used a cheap shimano grx 46/30 with an axs 10-36 cassette to get a 30/36 or 0.83/1 ratio. The axs 36T capacity RD is the best choice, but it works with the 33T capacity model too. Both models have the same wrap capacity of 42-43T. The lowest mtb ratio would be a 42/52, if you wanted a similar low ratio and a decent top gear.

FWIW, a 1/1 ratio is the same, regardless of chain ring and sprocket combination used to produce it.

Is this a typo? what does it mean? Most wouldn't be touching that ratio until 25mph or so.

So I can’t fully explain that.

I usually spin 75-85 rpm. So that should keep me happy up to about 22mph.

I just remember spinning out and bouncing an awful lot on the 38x11. Once I moved to 40x10 etc, the problem basically went away.

My guess is that the imbalance was the 38 with the other cruising gears, not the highest one. If you want a lightly used SRAM 38t NW ring, drop me a pm and I’ll I can get it headed your way.

So, sans gravel riding, I just finished chasing this unicorn. What is working for me is a mid 90's Trek mtb rigid, modded to a 1x. At the beginning of the hunt, I had a 22/32/42 paired with an 11-34 with a basic Shimano Altus RD. I paid close attention and deduced that 22/30 and 42/11 was occasionally used. This gave an operational ratio of 0.73 to 3.8
To nearly achieve that range in a single, required a 40 tooth narrow-wide front with an 11-50 cassette. That resulted in a 0.8 to 3.6 ratio range. So a little off each end I didn't use so much. The old Altus + goatlink handles the cassette. The only issue (this is recently modded and we are making minor tweaks) is tiny chain sound on the 42 tooth, and moderate chain sound and little skipping when under pressure with the 50 tooth. Mechanist and I are gonna try one less chain link and go from there. 11-42 pedals dreamily and I love the cockpit simplicity.

The one link subtraction worked and everything is happy!