bykemike 

I have a 2016 Domane 11 speed, Di2 shifting I am starting to use as a gravel bike. I am thinking I may be better running lower gearing than Ultegra 50-34 that came on it, do I have any options in this direction?

I expect one answer will be I have to change the entire crankset. Be nice if I didn't though.

Thanks!

zandoval 

Whats that largest cog in the back?

If there is a 34T in front then I at least want a 34T in back so I can go to 1:1. Even at one to one I usually can't maintain it for very long so I end up going to my Size 12-30". Over the past year I have been very happy with a 46/30 Square Taper Compact Crank from bikinGreen.

https://www.ebay.com/itm/124754009124

DaveSSS 

You have to change the crankset. The cheapest option is a grx-610 with 46/30 chain rings. The next is a grx-810 with 48/31 chain rings. Both will need spacing washers if you don't want a +2.5mm chainline.

t2p

if you have 11-28 cassette (?) - 11-30 or 11-32 cassette will provide a lower gear

might need a longer cage RD if the bike is equipped with short cage RD - and/or additional chain length (?) to prevent damage if you shift into 'big/big'
.

Steve B.

For 11 I would say a GRX 11 crank, 30/46 rings, you'll need a bottom bracket, about $170 all told. If you can source the crank.

SoSmellyAir

Pardon my ignorance; how does adding spacers to a crankset decrease the chain line? Or am I misunderstanding you?

jolly_codger

I recently bought a 46/30 chainring set for my 110mm BCD crankset (turning one of my bikes into something that will help this fat, old guy up hills). Look up "bikinGreen" and see if they have something that would work for you. I haven't put a lot of miles on them, but they look like a decent product.
John
PS I got mine on Amazon.

Steve B.

I was wondering the same. I'm pretty sure if you were to order a GRX 30/46 crank and get the appropriate bottom bracket, the chain line will be fine.

SoSmellyAir

I am not so sure. I understand that Shimano gravel cranks have a chain line which is further out from the centerline of the bike than its road cranks.

delbiker1 

Thus the appropriate BB for GRX

xroadcharlie

"I am thinking I may be better running lower gearing than Ultegra 50-34 that came on it"

Sometimes we over think things! Try it first. Unless you have some pretty challanging hills with soft gravel to climb, the 33 gear inches even a 28T rear cog gives you covers a lot of situations. If you have a 32T or higher rear cog, thats even better.

I think one gear lower (-10%) on firm gravel would require about the same effort as the low gear you use now on good paved roads. If you have that you"ll probably be fine with what you have.

HTupolev

The OP makes it sound like they have tried it.

In many places, the gravel right-of-ways are much more vertical than the paved right-of-ways.

Out in the Seattle area, I'm nearly always comfortable on a 34-28 on the paved roads. My gravel bike has a 24-32, and I make substantial use of that gear.

DaveSSS 

The chain rings are on the left side of the crank spider, so adding spacers reduces the chainline.

The cranks use normal 24mm spindle shimano compatible BBs. I use wheels manufacturing thread together with angular contact bearings.
I use these cranks with sram axs 12 drivetrain.

SoSmellyAir

Oh, you meant adding spacers between the chain ring and the crank spider (along the chain ring bolts), not between crank and bottom bracket (i.e., along the spindle).

DaveSSS 

Yes, since Shimano cranks and BBs don't normally need any spacers.

cyclezen

the whole compatibility thing seems somewhat complicated, especially when you review the Shimano guidelines, especially when it comes to Di2 setup.
The chainline may vary quite a bit going from 'road' to 'gravel' components, depending on the frame, the mix of Drivetrain components, and the FD compatibility for Di2.
I would expect the newer 'gravel' designed components would be designed for a 142+ rear width, not road or cx width - which affects chainline, especially for 2x.
Simplest might be to do a cassette range adaptation and get a Di2 RD which can handle the broader gear range. Then, though more costly, getting the chainrings which might fit the Ultegra cranks, 48 or 46 x 32 (30?) - don't really have a handle on what the lowest inside ring could be on Di2 compatible cranks.
...sounds/looks a bit complicated - not knowing how finicky Di2 can be...
Ride On
Yuri

SoSmellyAir

Exactly. The latest generation of 11 speed Shimano road cranks (R7000, R8000, R9100) are "optimized" for disc brake bikes (with a 142 mm rear hub spacing) and have a chain line that is 1.5 mm to 2 mm further outward than the prior generation (5800, 6800, 9000) which were initially released on rim brake bikes (with a 130 mm rear hub spacing). The Shimano GRX cranks have a chain line which is an additional 3.5 mm further outward. I had considered buying a GRX crank to use with my existing 11-28 or 12-25 cassettes to give a slightly lower gearing without the big gaps in a 11-32 or 11-34 cassette, but I am not sure whether I can adjust the derailleurs enough to compensate for the resulting chain line.

biker128pedal

If yours is like the new Domanes get a long cage rear derailleur and you can go up to a 34T in the rear. May be a 36T.