Originally Posted by
Darth Lefty
You can get the range you want out of a 2x11, but not all in one group. Specifically you need a Shimano 2x11 speed MTB RD, which is big enough for 11-42 and has wrap for a double front, and is different from the way more common 1x and is now last-generation or middle-group. At the front you need a gravel crankset (46-30), which might need you to get a road FD and flat bar shifter instead of the MTB hardware. You will be over the chain wrap rating but the rating is for suspension bikes and has some leeway.
15% more gearing range, with a double crankset…
9-speed, 26x36x48 cranks with 11-34 cassette, gear range:
Code:
( 48 / 11 ) / ( 26 / 34 ) * 100 = 570.629%
11-speed 30x46 cranks with 11-42 cassette, gear range:
Code:
( 46 / 11 ) / ( 30 / 42 ) * 100 = 585.45%
Now we're talking. If my maths are right, that gives me about 7% more range on the low end, where I need it, and takes about 4% of range from my high end, where I want it. That might be a reasonable compromise, compared to worse compromises.
I suppose one concern with fewer gears giving more gearing range, is not being able to find the "sweet spot" where I've got an ideal cadence to maintain an ideal speed… But in practice, I'm not sure how that would really feel, moving from a triple crankset to a double crankset, and how many "usable gears" I'd have.
IIUC, as long as I avoid absurd cross-chaining, it should be fine… If the frame can accommodate it.
My last two bikes, which were both used as daily commuters… I bought them set up mostly how I wanted them, made a few initial upgrades (eg pedals, saddles), and then just upgraded drive-train components after the OEM stuff wore out. A typical example would be upgrading from a Deore or SRAM PG950 cassette to an XTR or XT cassette; like I said earlier, that's within my comfort zone. This is worlds apart from speccing parts and building a bike, or even buying a new bike only to rip out most/all of the drive-train and rebuild it into something quite different.