Originally Posted by
downtube42
I have a vintage Windsor 2x5 that came with a 50-52 double. The cogs were far apart, so each rear shift was a large jump. The rings being so close, each front shift was asmall jump. So think about how that works: If you're on the big ring and want a small shift up, you shift the ring down and the cog up. If you're on the small ring and want to shift up, just shift the ring up. And so on.
1x and compact double are both sort of the opposite of that. Super simple shifting.
Originally Posted by
xroadcharlie
Actually my first 10 speed from the mid 1970's was kind of like that. Switching the two chainrings pretty much staggered the gears on the cassette. Giving me 20 distinct gears. The next bike I bought was a 12 speed...Even better I thought. Ha, The bright engineer that designed the drivetrain pretty much copied each gear except one. Da...so 12 speeds is now 7.
On my new 21 speed bike their are still only 13 distinct gears. But it works out well for my riding anyway.
That's known as 'Half-Step' gearing. It was pretty common through the 70's and in to the 80's especially on touring bikes, as a way to get a wide range of distinct 'gears' when the tech of the time only supported 5 or 6 speeds at the back.
With any 2x or 3x system, you're going to get some 'overlap' of gear ranges, especially if you're running a 3x front, and -7 or higher in the rear. The reason for more and more 'speeds' on the rear (and fewer 3x cranks) is twofold. Shifting the rear is much easier under load, like climbing or sprinting, as well as being faster and (generally) more accurate, because the rear derailleur is on the 'return' or slack side of the drivetrain, the RD doesn't have to fight against pedal tension to move the chain across the gear cluster. In the front, you are shifting the tension side of the chain, so going up, or down, you have to 'back off' on the pedals for a half-a-rotation to get the chain to drop or climb smoothly.
Add in the wide range of sprockets you can run in a single -10 speed cassette, and a 3x crank gets you a lot of duplicated gears, in order to get one or two really extreme (low) ratios.
2x cranks also give you more clearance between the rings and frame, which helps with the trend towards wider tires on gravel and 'all-road' bikes.
Also wrt to the demise of triples; Integrated, indexed 3x shifters ie: STI's/Rapidfire/Doubletap are much more sensitive to setup than 2x front shifters (esp, the middle gear) They're not all that hard, but 2x are really simple.