Edit: Rolhoff has heard my plea for wideness and introduced a 170mm version of the Speedhub. Now if I could only afford one…
In general, I’m not a big fan of derailleurs. I like riding single-speed, or using an internal-gear hub (IGH) in most cases when gears are desirable (which is, to my thinking anyway, a lot less often than you’d think).
But, if there’s anything that riding a low-geared single-speed fat-bike has taught me (besides the use of hyphens), it’s that while the chance of having the wrong gear is no higher than any other type of single-speed, the detrimental effects of that wrongness are greatly magnified. I’ve done some awfully fast spinning on flat pavement lately, as well as some painfully low-cadence grinding through soft and jumbled snow.
If I’m going to avoid using derailleurs — and it seems like a really good idea to avoid them given most of the range of fat-biking conditions — that leaves me with an IGH such as a Shimano Alfine or a Rolhoff Speedhub.
On any bike, using an IGH requires a frame that provides a way to tension the chain (in the same way that a single-speed does) — whether it be track ends, semi-horizontal dropouts, sliding dropouts, or an eccentric bottom bracket. This is a limitation in itself, though not one that’s a problem with fat-bikes, as there are quite a few options.
The limitations arise, however, if you want to use an IGH with a non-offset frame with a rear OLD of 170mm (or greater, since things seem to be getting bigger all of the time).
So, I wish that both Shimano and Rolhoff (as well as perhaps SRAM and NuVinci) would make versions of their 32-hole disc hubs in a 170mm OLD.
Wishlist is an occasional series dedicated to things that I wish that someone or some company in the cycling world would produce. Most of it is probably just whinging.