Since you can use different rings with the new shimano can you run 53/34 easily?

Yes but shifting will be effected.

That's a big jump up front. Couple of issues come to mind aside from less than optimal shifting... 1) dropping chain on inside while shifting from big to small, 2) having enough capacity on your rear derailleur to wrap enough chain in some of the small/small combinations, since you'd have to have the chain long enough to fit the big/big. May need a long cage derailleur.

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Colnago C60 - PR99
C59 Five Years Later
My Special Colnago EPQ
Trek Emonda SL Campagnolo SR

Thanks for the answers!

Shimano front derailleurs have a 16 tooth max difference...

when i was running a 50/34 with a shimano fd (5700) it looked like you run few teeth outside the max limit they state. not sure by how much tho

Why wouldn't you just run a bigger cassette?

(Sorry someone had to)

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Bikes: Raw Ti, 650b flatbar CX

for me at least, the 2t jumps between cogs in some wide-r range cassettes is really irritating.

The reason was for a one time use situation like 6 gap century. All ready will be using a 28t.

I don't even like how much I have to go between big ring and small ring up front with a 50/34 (I only use the compact crank if I were to be doing a multiday trip in the alps or something. Otherwise I much prefer a standard 53/39 setup for pretty much everything and just swap cassettes where needed... Anything from 11/23 on up to 12/29. With this setup I don't have to swap chains and I can just swap wheels with any combination of cassettes from 11tooth at the smallest up to a 29 at the other end. Mostly use 11/25 and 12/27 cassettes. I think there's a better solution that going with a 53/34 combo, if you can even get it to work.

_________________
Colnago C60 - PR99
C59 Five Years Later
My Special Colnago EPQ
Trek Emonda SL Campagnolo SR

I don't like the 50/34 jump either, swapped my inner over to a 36. Gives almost the same ratio jump as a 53/39, and with 10 speed and a 25 or 28 sprocket, I can still get a low enough gear to haul my fat arse up anything.

I remember seeing a Belkin bike earlier this season (possibly several) with a 53/36 combo that was working fine. That was with Di2 though.

I know a guy who runs a 53/34 on an FSA crankset. He likes it because he pretty much stays in the 53 on group rides and races, but can use the 34 when he makes trips out to the mountains.

I don't know how affected shifting is.

Did the Etape this year with 53/34 on Zipp Vuma Quads. Think i ran 11-25 at the back. Shifting wasnt great but then i only made 3 front shifts and really appreciated being able to spin towards the end. Would be worried about chain drop on every day use.