Triple chainring spacing.

[andrew_s]

The restricting factor in relation to chainring options is the depth of the inner cage plate. The mech has to be set up so the bottom edge of the plate misses the middle ring when changing up to the big ring

This normally appears in the front mech specs as a minimum difference between outer and middle chainrings.

I'd be inclined to try 50/38/26 as a first choice (or 24 - if you're going little, there's no point in half measures)

[toontra]

Actually I've decided to try swapping the 11-28 cassette for a 12-30 with 52/40/26 rings. Hopefully that will avoid any FD issues (which have been the bane of my cycling life )

[peetee]

The restricting factor in relation to chainring options is the depth of the inner cage plate. The mech has to be set up so the bottom edge of the plate misses the middle ring when changing up to the big ring

This normally appears in the front mech specs as a minimum difference between outer and middle chainrings.

I'd be inclined to try 50/38/26 as a first choice (or 24 - if you're going little, there's no point in half measures)

It does but in other posts I described how my reduced outer chainring size (48t + 39t) contravened Shimano’s spec but works fine with careful positioning of the mech and a suitable cassette. In short, some options can still be found with a bit of trial and error.

[CJ]

Going to a 26t inner might make the down shift less crisp (or even hesitant), especially if you cannot lower the mech as mentioned above.

Don't worry about that. When shifting off the middle ring, neither the mech nor the chain have any idea how small the inner might be. The chain simply falls and lands on whatever may be down there, hopefully some teeth on an inner ring.

The further it falls however, the greater the chance of it missing those teeth, so you may find a Jump-Stop more necessary. It's always a good idea to fit a Jump-Stop with a triple, even if you haven't reduced the size of inner, the mech cage is already too far away to guide the chain effectively.

One other possible snag: the chain might now run so low in the cage that it rubs on the bottom of it, especially when the smallest rear sprockets are engaged. I tend to replace the stock 30 with a 24, so I do have that on one bike, but I don't worry about it because I don't need or even want to use the smallest sprockets with the smallest ring. Those combinations are too far out of line for efficient use and are duplicated by smoother-running gears on the middle ring, so I'm actually grateful for the rattly reminder to shift up at the front!

[Bmblbzzz]

Depending on chainring design, inner ring and small sprocket combinations can also cause the chain to rattle on the pick-up pins. Another reminder that you really ought to be in a bigger ring!

[toontra]

Depending on chainring design, inner ring and small sprocket combinations can also cause the chain to rattle on the pick-up pins. Another reminder that you really ought to be in a bigger ring!

True! I spend so much time in the middle ring that occasionally if I'm on a long climb I forget I'm on the inner by the time I get to the top and as I gear up at the rear I get the grind/rattle

[Bmblbzzz]

If you're really unlucky in that situation, the chain will get caught on the pins and refuse to move to the next ring. Or even stop get jammed. This is not a good feeling.