There isn't a good and bad, it's what works and doesn't. A fat bike is NO DIFFERENT than any other bike. The bike is build with added spacing for clearance. But adding cogs means at some level added width, so may cause an issue depending on hub spacing, chainline, and desired rear tire.
Just like trying to squeeze a 4.7 tire in a 170 frame. May fit the frame but the chain becomes the issue. If you have the clearance, then do it.
But be advised, something these companies don't want people to realize:
Bigger the rear cog to mate up to bigger front chainring, the the faster your going to eat rings, cassettes and chains. Mostly chains. The bigger the rings and cogs, the more lateral stress is put on the chain. And it's not little amounts, it'll be noticed very soon by riders adopting this retarded 1x setup (I ride 1x on 2 of my bikes, largest rear cog is 40 and largest chainring is 32, 42 I could consider but that's my limit)
The other thing is, your added now measurable rotational weight. So your literally beginning to cancel out all benefits of 1x EXCEPT simplicity. So what's the point???? A good 2x system would give more range and be more durable. Do believe me, make a mental note and check back in 1-2 years when we see how fast chains and such have to be replaced compared to before this "phase" of putting massive cogs on a cassette and calling it an upgrade.
One more thing, your willing to sacrifice climbing gear for more top end? If you get totally spanked on the climbs that top end coming down isn't going to save you in a race. Plus that 1 tooth is going to due next to jack crap cause all the guy next to you has to do is spin a tiny bit faster and hes right back in front.
Unless it's flat ground or a downhill race, races are mostly won on the climbs. If your last in the climbs or more taxed at the top than the other guys, their going to have a gap on you a fast down hill where your a fair bit faster will do you no good.
Ive raced, learned the hard way fast. I could hold my own for my skill level on the flats and downs, which there were more of, but the couple climbs I got spanked and by the end... well I'll leave it at that.
So think about all this before choosing your gearing and ditch the marketing bs. Look at what's really going to make the most of you as a riser, not what marketing is trying to say will give you and edge. Cause it's the rider 95% over the bike.
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