Originally Posted by
jppe
I think you can "future proof" by using BikeWNC's method he discusses in his post. By using a compact double along with a MTB RD you can have gears that are even easier than most standard Triple setups. I've been using that arrangement for several years and it works perfectly. The new 10 sp 11-32 to 12-36' cassettes also allow for a very wide range of gear inches.
Yes, with the latest cassettes and compacts, you can get amazingly low gears. But NOT as low as with a triple, and there will be a penalty in gapping and possibly duplication. You can still get more benefit from a triple. We're talking about being prepared for the future, which the OP sees as having a significant downside, though he doesn't really say why he expects this. A triple setup that allows for very small grannies is the most flexible platform, from a gearing adaptability point of view, given taht he selects and sizes the crankarms to best fit his body.
Keep in mind that with a triple you can do a 20 tooth granny and the 36 tooth rear cog. Now the limitation will get into total chain wrap capability. 40-some teeth wrap might not seem like very much.
With an Impel or similar you can do a 44/36/20, for a 24 inch tooth spread. With an 11 tooth small cassette you will get a 100 inch gear. With the 20 in the front and a 28 in the rear you get Frank Berto's target low gear, 19 inches. So 44/36/20 and 11/28 gets you a wrap requirement of 41 teeth. I think there are a wide range of long-cage derailleurs that can handle this.
If you're a weight-weenie this won't be your cup of tea. But for you avowed goal, it fits the bill. But you still need to fine tune the cassette and chainring selections.
Note I'm not talking about a standard triple but is an available part, at least on Ebay.