The internal-geared hub has been around for decades, commonly found on city-cruisers & touring bikes. They’re nearly impervious to dirt & water; have a robust construction, and are available with a wide variety of brake options. These include the classic coaster-brake; the roller-brake; modern disc-brakes, and the v-brake-friendly freehub. Each manufacturer has their own take on the design, with gear ratios ranging from hill-slayer low, to speedy-city high. So conventional wisdom would suggest that these hubs would be ideal for use on mountainbikes….. Unfortunately, this isn’t always the case…. Until recently.
The biggest problem with geared hubs has always been weight & complexity. With city & touring bikes this isn’t a large concern, as they are meant for level, smooth terrain; and such bikes often have other weight-adding accessories (racks, lights, fenders, baskets). A fairly narrow range of gears doesn’t affect the average city-dwelling bike commuter, so these geared hubs, on average, have a lower gear range to help get a heavy bike moving.
This gearing & weight factor has kept these hubs from making the full leap onto mountainbikes, as not only do they have a low range, but they are commonly found with between 3 and 9 “speeds”. Couple that with often only one or two smallish chainrings (typically 36t-40t); a rider on a bike so equipped will find him/herself walking up steep hills, or spinning-out on moderate/steep declines.
But a few mountainbike builders have begun utilizing internally geared drivetrains. Some of them are specially adapted commuter drivetrains, others are in-house designed & made. The GT IT-1, Nicolai Nucleon TFR, SR Suntour G-Boxx, BeOne Petespeed, and Honda RN01 are all either production bikes, or semi-production prototypes.
A few of these gearboxes (such as the Hayes & SR Suntour Design) are essentially derailleurs in an aluminum case. Others are based on the already proven commuter hubs, or planetary-gear transmissions. Such gearboxes are currently only being fitted to downhill & freeride bikes. These bikes, with over eight or nine inches of suspension travel, are greatly aided by reduction of unsprung weight at the rear wheel. This puts less of a demand on the overworked suspension of a gravity bike, and attaining more responsiveness from suspension designs. As an added bonus, a mid-frame gearbox moves the bike’s center of gravity inwards, as well as lowering it, depending on gearbox placement. This makes for a more stable and balanced bike.
These internal frame-mounted drivetrains still have drawbacks; limited gear ratios, weight, complexity, and frame-specific designs all reduce the likelyhood that such gearboxes will be mass-produced for non-race/prototype bikes, or gain acceptance by the bike industry as a whole. The average (yet adventurous) rider will still be looking for a drivetrain that he/she can fit onto their regular trailbike (hardtail or full-susser). They’ll want something which offers only a small compromise in gearing and weight for a gain in durability and resistance to the elements.
A German firm, Rohloff AG, began producing the Speedhub in 1999. Its wide range of gears (14), evenly spaced & huge spread of gear ratios, ability to change gears at a stand-still, durability, and low maintenance requirements has set the standard. In the past few years, the Big Two of making bicycles go (SRAM & Shimano) have been at work manufacturing geared hubs that are lightweight, durable, and efficient. Shimano & SRAM are still behind the curve compared to the Speedhub, but they are catching up. These three companies are well known to bicyclists around the world. But there is a fourth that has been in business and making geared hubs since 1902. Sturmey-Archer is an English manufacturer that pioneered geared hubs and drum-brakes for both bicycles and motorcycles; and developed one of the first electricity-producing (dynamo) hubs. In 2000, Sturmey-Archer was acquired by SunRace, and together they have designed modern hub brakes, roller brakes, 8 speed geared hubs (dynamo optional), as well as 3 & 5 speed hubs.
As mentioned before, the Rohloff Speedhub has been the high-water mark for all internally-geared bicycle hubs. In 2005, Fallbrook Technologies released a revolutionary hub system that could very well unseat Rohloff. The NuVinci CVT uses no gears, only a set of rotating & tilting balls contained between the input & output transmission components. The magic in this design is the “traction fluid” which reacts to friction, instantly turning from a liquid to a solid. While the NuVinci is much heavier than any other geared hub on the market, if developed further, it has the potential to at least equal the Rohloff as being the most suitable for use on mountainbikes.
This section contains a list of internally-geared hubs; their manufacturers; weights; and gear-ratios (if available), as well as available braking systems. Comments on mountainbike applications will also be included.
- SRAM i-Motion9: 9-speed, gear ratio range= 340%; weight- 2400g/5.3lbs; coaster-brake, disc-brake compatible, or freewheel only.
- The i-Motion9, though the heaviest of all the hubs listed here, would be a smart choice for a rider looking to convert a hardtail MTB into a hardy trekking bike. The gear ratio is fairly high, making hills a little difficult, but allowing for higher & more effortless cruising.
- Shimano Alfine: 8-speed; weight- 1590g/3.5lbs; disc-brakeonly.
- The Alfine could very possibly replace a low-quality derailleur, cassette, rotor, and freehub on any trailbike. Combined with a triple chainring, this hub would provide an acceptable range of gears, as well as reliable operation in nasty trail conditions.
- Sturmey-Archer XR Series: 8 speed, gear ratio range= 305%; weight- 1510g/3.32lbs; different hub series available with coaster-brake, disc-brake compatible, 70mm drum brake, roller-brake, or freewheel only.
- An XRK or XRD hub is most likely the best choice for replacing a standard drivetrain on a hardtail or full-suspension mountainbike. The gear ratio is on the low side, which means easier hill attacks. The Sturmey-Archer 70mm drum-brake could be the most powerful mechanical brake in existance; certainly on par with most XC hydraulic disc-brakes. In addition to power, these drum brakes are protected from moisture and contamination, which means reliable stopping in all conditions.
- Rohloff Speedhub: 14 speed, gear ratio range= 526%; weight- 1825g/4.02lbs; disc-brake compatible.
- The Rohloff Speedhub has been used on many mountainbikes, both hardtail & full-suspension. It’s robustness and gear range is well-proven and liked; and if the extra weight is disregarded, the Speedhub is an easy choice for replacing a tired standard drivetrain, or building a unique trailbike. A negative aspect of the Rohloff is the pricetag: $1500. Yes, this is very expensive; the engineering, versatility, and durability easily makes the entry-fee reasonable.
- NuVinci CVT: Infinitely variable gearing (.5 Under-drive to 1.75 Over-drive), gear ratio range= 350%; weight- 3850g/8.48lbs; rim-brake, disc-brake, or roller-brake compatible.
- The NuVinci is very…. new… And as of yet, it has only been featured on one production bike, the Ellsworth Ride.The NuVinci is also very heavy, making it currently unsuitable for anything but cruiser bikes like the Ellsworth. Fallbrook Technologies has stated that they are working hard to reduce the size and weight of the NuVinci, and make their way into the mountainbike drivetrain market. When this happens, the NuVinci will be a very interesting option for any mountainbike.
Lastly, I will mention an innovative drivetrain component that would compliment any of these geared hubs. This is the Schlumpf MountainDrive.Â
The Mountaindrive is a planetary geared crankset, which provides either a 1:1 ratio, or a low 2.5:1 ratio. This system can also be set up to run two chainrings, and will offer a much greater range of combined gear ratios than a standard 2/3 chainring crankset.
As bicycle drivetrains go, the derailleur has been around basically unchanged since the late 19th century. It is a fairly simple and effective method of multiplying our limited muscle-power. But as a species of tinkerers and inventors, the quest for something better has always existed. In the automobile, advances in transmission technology has happened quickly, if only because the large size of these parts allows for a greater range of experimentation. But with bicycles, we are dealing with an engine that will always give the same power output; and mechanical parts that are by necessity very small. Small parts require more precise tooling and tolerances to manufacture, and before CAD & CNC operated design/milling came about, the means to provide internally-geared hubs with the same versatility & quality as derailleurs was not physically or economically feasible.
Our sport is benefiting greatly now from these computer-driven manufacturing & design processes, and the parts we hang off of our bikes are evolving at a faster pace than has ever been seen. This is an exciting time, for both gearheads and riders; veterans and novices. While simplicity is beautiful, there will always be room for the exquisite intricacies of advanced bicycle technology.
