How well can the s40 handle smaller 2x front chainrings with di2/etap?

[lacohe]

I recently picked up a s40 which has been great for me. It has been so long since I've gotten off a bike without pain, and I even remarked to my partner that it's surreal finishing a long ride and not experiencing nerve pain for the next couple hours.

With that said, I have been eyeing some groupset upgrades for the future. While I like the range of the apex 1x, I don't like the big jumps between gears especially around threshold efforts. I've been looking at past posts over the years regarding the front derailleur issue on the v20/s40 not handling compact (or smaller) chainsets well. However, I've read mixed reports where some have said di2 50/34 and axs etap 46/33 work without issue ("fine").

Given the cost and time of purchasing and installing groupsets, I was hoping to get any updated information on how well either work out of the box. Is it as smooth as one would expect for a standard setup, or does it 'get the job done'? Are chain drops still an issue as previously mentioned with their mechanical cousins?

 

[Frito Bandito]

I ride a V20 with SRAM AXS, and since it is always on the flats I ride with larger (52/36 or a 54/40) chainrings so keep that in mind. I got mine set up right and never had any issues with it on the front or rear. For some reason I couldn't ever really get mechanical groupsets to work well, no matter how many videos I watched or manuals I read so I decided to give AXS a try. Once I put AXS on and went through the app settings to microadjust the rear derailleur during Corona it has pretty much been flawless since then. My derailleur stalk maxed out at the 54t size, but since I am older and prefer a slower cadence I switched the 54t out for a 58t. The front derailleur won't fit so I just keep it on the 58t all the time and can kick it over to the 40t if required. So, I essentially run as a 1x now. With all that said, I don't think you'd have any issues with chain drops using an off-the-shelf crankset, or have any shifting issues as long as the pull ratios on the cassette match the rear derailleur. FWIW I am using 12-speed Ultegra cassettes on 2 sets of Mavic CXR wheels (11-34 and 11-36) with my long cage SRAM 12-speed AXS derailleur.

 

[Greg S]

On a previous S40 I ran a 50x34 crankset with an 11x36 cassette. Worked great and I'm rather compulsive about perfect shifting.

I'm in the process of putting a subcompact (48x32) on my V20c. There's a thread in the V20c sub-forum where I'll be posting updates if you're interested.

 

[chicorider]

I ran Shimano Dura Ace 11-speed mechanical 2x on my V20 and V20c (and still on my S30) with good success. I didn't love the finger effort needed for the front shifting lever throw, but it always worked fine, and a K-Edge Pro chain catcher kept the chain from falling off the inside. No complaints, and the rare need for adjustment was always easy. After a wipeout in a road construction zone (I didn't see the uneven surface seam), I went looking for replacement 11-speed parts and found that after several years out of production, they were almost as expensive as the current 12-speed Dura Ace Di2. I have long been a hold-out regarding electronic shifting because I didn't want to deal with battery headaches. But I was finding good prices on DA Di2 12-speed with wired shifters that used cabled braking, so I went for it. I was already using Growtac mechanical disc brakes, and I wanted to keep them. In short, I love it. Shifting, front and rear, is spot on, and the front shifting shifting requires no effort at all. Puzzling through the installation and running the wires took some thought, but I came away with a super-clean install, with the wires mostly invisible. I like that I only have one main battery to tend, and it goes a ridiculously long time between charges. Some of that has to do with my shifters being wired instead of wireless. I have heard that the wireless shifters will cut the battery range by almost half, but you gain ease of installation (and two more coin-cell batteries in the shifters to manage). Shimano Ultegra Di2 should function just about the same. I know I don't need Dura Ace, but bikes have long been the one thing I splurge on under the you-only-live-once philosophy.

I would guess that SRAM AXS functions just as well, and has the advantage of easier installation. I have heard that battery charges last a while, but not as long as Shimano's main battery. And with SRAM 2x, you have four batteries to monitor. Not a big deal if you are on top of it, but I have been on rides with folks running AXS where either a coin-cell battery or a derailleur battery has run out of juice, and they either had to abandon the ride with an inoperable bike, or limp home with partial service. I know that can happen with Di2 as well, but for me, a guy who adopted electronic shifting somewhat grudgingly, juggling one battery is much simpler than four.

I run 160mm cranks with Rotor oval chainrings, 36/52t, and a Shimano 12-speed cassette, 11x30. The gear gaps are nice and tight, and I have enough gearing to climb all of the hills around me. I liked the DA Di2 setup enough to put it on my Specialized road bike as well, with the same gearing. I have a separate 11-34 12-speed cassette that I bought, just for rides with steeper hills. I've only used it once, on the road bike, on a course with grades up to 27%. One thing I appreciated about the Di2 is that I didn't have to do any adjusting between cassettes; the chain was long enough for the 34t, and the rear derailleur handled the switch without issue, making it easy to swap back to the 11x30 after that ride.