Ultegra w/o front derailleur

I run and Ultegra Di2 on my triathlon bike. I am going to The Championship in Slovak and the course is super flat. To improve aero, I am thinking of leaving front derailleur off completely. Di2 seems to work correct as 1x11. My worry is that will the chain stay or will it drop to smaller ring with larger rear gears? Any experience?

If you’re just removing the fd, and everything else stays the same… then I suppose it’ll work just like your normal set up. I dnt think you’ll have a jumpy chain.

If you’re doing it on a perm basis, you can remove the little ring and put on a narrow-wide larger ring, that’ll help with chain stability.

I’m building a 11-32, 52t 1x and have bought a narrow wide chain ring

My biggest worry is that Ultegra 2x11 chainring is shaped for shifting, whereas a ring built for 1x11 is not shaped for shift

Don’t do it unless you put a 1x chainring on……if you just use a standard CR, there is a decent chance you’ll drop your chain.

Ask David Millar……cost him the yellow jersey.

You are talking about saving a couple of seconds, max….not worth it, IMO.


Yeah, unless you know the missing FD will give you the last bit of W you need…the risk would be too high for me. Drop your chain without a FD, and you’ll lose 30s at best, possibly more, depending on where it drops to.

Exactly what I am worries about :slight_smile:

What would be a good 1x11 chainring that fits Ultegra R8000 crank? Or would it be 1x11 crankset straight away

How soon is the race? You might not want to be making changes close to it in case you need bigger/smaller rings/cassette.

Ring wise I’ve had good experiences with random eBay (snail I think is my current ring) rings for my XT cranks. Pretty cheap too which might mean you could buy a few sizes at once to allow you to sit in the middle of the block.

Garbaruk has a bunch of options in round and oval. I just threw an oval 1x on my cross bike and have no complaints yet. Not sure what the durability is though, I have less than 50 miles on it.

For me the risk is too great. :smiley: With no narrow/wide chainring on the front and no derailleur there is a very real risk of hitting a bump or a manhole cover and bouncing the chain off the front chain ring. So you would be securing some small aero gain and risking absolute disaster. BIG risk, small reward.

Thanks for the insights, confirmed my worry, so ordered a Rotor round ring for 1x11 (https://www.bike24.com/p2378108.html)

I’ve run 1x with ultegra DI2 (or some variation) for a couple of years. I think you’ll want both the narrow/wide chainring made for 1x use and also a new RD with a clutch. I am using a XT Di2 RD since that is what was available at the time, but there is also the GRX line RD now.

Of course, gotta check the Shimano compatibility chart:

For a TT bike, I think you can skip the clutch RD. I’ve run a 1x Ultegra mechanical setup for about 18 months on my gravel bike with the stock RD. Dropped a chain one time, I think.