With narrow tires, no suspension, and road-inspired geo, gravel bikes aren't the first place we'd look for off-road innovation. That could be changing, though, as Cycling Tips
spotted this Classified hub that expands the range of a 1x groupset. Some gravel bikes are now offered with 1x groupsets as it simplifies the frame design and increases tire clearance, but it often comes at the compromise of a smaller overall range.
This Classified hub hopes to remedy that by giving riders more range with the same cassette, effectively acting like a two-chainring setup but with the same minimalism as a 1x set up. Internally geared hubs are nothing new, of course, but most of them are bulky, heavy and normally work with a single cog on the rear. But the Classified hub is much sleeker, and it works with their own proprietary cassette but doubles the selection using by two internal planetary gears. It's a bit like having a 2x set up, but with the front derailleur and the extra chainring in your hub, not at your bottom bracket.
Inside, the two planetary gears offer 1:1 and 1:0.7 ratios, giving you a lower (easier) range than what your traditional setup might suggest. For example, if you have an 11-34T cassette on your gravel bike, you would expect to have a 309% gearing range, but the Classified hub will increase this to 451%. The shifting is wirelessly controlled and the hub can apparently get it done in 150 milliseconds. It's also claimed to work under loads of up to 1,000 watts. Hhmm, maybe no big sprints then...
At this point in time, Classified hubs require a proprietary cassette and there are currently four on offer, from 11-27T to 11-34T, which, when combined with the hub, offer 358% to 451% ranges.
Classified's chart showing the available gear ranges
The electronics are all housed in the thru-axle, including the removable battery. The system works with induction coils so there are no wires to contend with at the hub, and Classified claims the battery will last 10,000 shifts, or roughly three months of riding, between charges. Weights haven't been published yet but are said to be comparable to a 2x set up; of course, this weight is unsprung being in the wheels and not in the frame where the added 2x gubbins would normally be. We're also always suspicious of drag in any gearbox system, but Classified claim that there's no extra drag in the 1:1 ratio while the 1:0.7 ratio is said to be '99% efficient'.
If all of this sounds like something that interests you, you'll have to wait a little while yet, unfortunately. The system is currently only offered on the top-spec Ridley Kanzo Fast, with seemingly no aftermarket options available at the moment or coming any time soon.
It also only seems to be compatible with Shimano Di2 road levers at the moment, which won't be much use to mountain bikers unless they're brave enough to try to modify their Di2 off-road shifters.
The system uses Classified's own cassettes that are compatible with existing Shimano 11-speed road drivetrains, so there's no chance of upgrading your current set up yet.
That's not to say we can't see it being developed for mountain biking applications in the future, though. The advantages are obvious; instead of increasing range beyond the 520% we already enjoy, we could see this being used to get that same range without dinner plate cogs. Instead of a 50+ rear cog, you could get the same range with a 40T rear cog and have twice as many ratios to choose from as well.
There are, of course, plenty of questions over strength, weight, reliability, efficiency, and cost still remaining but Classified's hub could be a way to get all the range of 2x without sacrificing the benefits of 1x.