|Not all front derailleurs are weak, ineffective, or a hassle to use.|
I'm not going to go where you think with this rant, by the way. Nope. Gear range is a conversation for another day. What concerns me is something I've not seen mentioned by anyone until very recently. There was a review on an all-road bike posted recently on the "Bike Radar" site, and in the review on this particular bike equipped with a "one-by" drive train, you can find this gem:
Shifting across the wide 11-32t cassette is no different to any other SRAM DoubleTap groupset, with just a little extra noise in the biggest cog, where the chain is at its most extreme angle.Did you catch that? The bit about the "extra noise" when the chain is in the "most extreme angle"? Think about that for just a minute......
What is it that you've heard preached about when using a multiple geared drive train? Long ago, Keith Bontrager had an article in "Dirt Rag" which covered the four cardinal rules of shifting. In that piece he described how one of the principle rules of multiple speed drive trains was to keep the chain line as straight as possible. Why? Because a straighter chain is more efficient. A chain that angles from one cog in the rear to another chain ring on the front becomes less efficient as the angle increases. This accelerates wear as well. In order to maintain a straighter chain line, the rider should shift the drive train into an appropriate chain ring up front. Then use the rear cogs on the back the more closely approximate a straighter chain. This keeps efficiency high and reduces wear to a minimum.
|With only one front ring, there is no way to correct for extreme chain lines.|
In my opinion it is because the appeal to riders is that it makes understanding the drive train easier. To a lesser degree, it also helps you to get a slightly lighter drive train. Finally, for mountain bikers it clears up enough real estate on the handle bar so that a dropper post remote has a place on the bar without being affixed in a strange, poor ergonomic position. However; it would seem nigh unto impossible to show that it is actually more efficient unless you spend the majority of your time in the middle of your cassette, in which case the higher gears and lower gears are essentially dead weight.
This also doesn't even touch how shorter cage rear derailleurs shift more quickly, and are lighter, or how you don't need enormous rear cogs which rear derailleurs aren't the most efficient at shifting into or out of. It doesn't begin to tell how that big cog/front ring chain line is actually more severe than a typical 2X set up. Nor does it touch on how some front derailleurs are actually quite easy to shift and these don't have to be electronic either. Finally, multiple front chain rings distribute wear across more material/teeth, and a single front ring is going to wear out faster.
While a "one-by" chain ring set up might seem really cool for your bike, it has its drawbacks and compromises. Something to think about before you "make the leap".