It’s a no-brainer that weight is saved with SRAM’s 1 by 11 system, but at first glance, looking at the additional — and huge — 42-tooth large cog and the bigger rear derailleur, one might think it to be trivial. But just eliminating the front derailleur cable and housing drops 30 grams off of the bike — about as much as the additional dinner-plate cog adds.
Then leaving off the front derailleur, left shifter, a chainring or two, their associated spider-arm mounting platforms and chainring bolts, and you have some real weight savings. And that’s before frame designs adapt to no front derailleur.
To accommodate the 10-tooth cog (and perhaps smaller ones in the future), the freehub body is different from what we have used on our bikes for decades.
That may not require new wheels, however. Even though XX1 is not yet in stock (it’s going into production three weeks from now), wholesaler QBP already has DT Swiss freehub bodies and end caps for XX1 in stock that can be retrofitted onto DT Swiss hubs and many other brands that DT Swiss builds the hubs for.
There are hidden benefits of that freehub change, too. Now the first cog is not a separate one — the XX1 cogset has 10 cogs machined in a single piece of steel with a 42-tooth aluminum cog riveted on the back. The lockring is inset within that tiny first cog and threads deeply into the freehub body, under the third or fourth cog. This stabilizes the cogset and reduces wear on the freehub’s outer bearing more than the traditional lockring out on the end.