Rohloff Speedhub
From Wikipedia, the free encyclopedia
The Rohloff SPEEDHUB 500/14 is a 14 speed epicyclic internal hub gear for bicycles. It has 14 equally-spaced sequential gears operated by one twistgrip with no overlapping ratios. The gear range is wider than that of 27-speed derailleur systems. The Speedhub 36 500/14 has a gear range of 526 %, which means that the highest gear is 5.26 times higher than the lowest gear. Across the entire range of the 14 gears shifts increase or decrease in even increments of 13.6 %.
The Rohloff is a little heavier than a triple-chainset derailleur drivetrain with a similar spread of ratios. Being completely sealed it requires substantially less maintenance, especially when combined with a full chaincase. It can be used with a wider chain than most current derailleur gears, which reduces wear on the driving gears. Gear changing is smoother than a derailleur; gears are changed when there is no pressure on the pedals. It is slightly less efficient than a clean and lubricated derailleur system and is much more expensive (currently around two to three times the price of a capable triple chainset, rear derailleur, cassette and hub). It is noisy in the lower gears, although users report that the noise is much reduced as the hub wears in.
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[edit] Versions
There are several different versions of the hub for different applications that a bicycle might be used in:
- TS (Touring Axle)
- DB (Disc Brake)
- CC (Cross Country)
- EX (external Gearbox)
- OEM (original equipment manufacturer)
- OEM2 (like OEM, for frames with Disc Brake mount, after IS 2000)
- T (Tandem)
The hubs are available in different colors: silver (aluminum polished), red or black.
Depending on the type of dropout slots on the frame the sag of the chain can be adjusted differently. The usual type of dropout slots for hubs, which are open in an angle to the front side, is long enough to tighten the chain by moving the back axle up or down. For short dropout slots at frames built for a regular chain derailleur system you will need a suspension strained chain tensioner. The same applies to back wheels with suspension, because the distance between crank and back wheel is changing while riding due to the suspension. It is also possible to tension the chain using an eccentric bottom bracket.
[edit] Technical
[edit] Operation
The internal construction of the gear hub consists of three planetary gear systems, connected one after the other, which are selectively engaged depending on the user’s gear choice. The first two gear systems provide seven ratios, doubled to fourteen by the third gear system. Unlike other hub gears[citation needed] the Speedhub is built mainly with roller bearings for efficiency. All components are immersed in lubricating oil.
The IGR, hub revolutions per sprocket revolution of the Speedhub, lies between 0.279 and 1.467 depending on the gear chosen. The Speedhub has a 526 % range between the highest and lowest gear. Gear 11, with a ratio of 1.0, is called the neutral gear.
The overall average loss of the gears is about 1 %–5 %, comparable to a derailleur.
The range of gears in detail is shown in the table below.
| Gear | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| IGR | 0,279 | 0,316 | 0,360 | 0,409 | 0,464 | 0,528 | 0,600 | 0,682 | 0,774 | 0,881 | 1,000 | 1,135 | 1,292 | 1,467 |
[edit] Mounting
Hub drive systems such as the Speedhub require that the differential torque between the hub’s input (driven cog) and output (back wheel) must be routed to the bicycle’s frame. This can be affected by a specially designed wheel dropout slots (OEM versions), or a torque fitting that connects the stationary components of the hub to the bike frame. Both options prevent movement of the hub, providing a stationary (relative to the bike frame) structure to carry the various gears, bearings, and other power-transmitting components.
The shifting mechanism carries operator input to the hub from a twist shifter over two shifter cables. The gear stops are integrated inside the hub, as opposed to other solutions which have the gear stops in the shifter. Since gear indexing occurs within the hub mechanism itself, the shifter cables of the Speedhub can be left untouched once adjusted. If the cables are installed out of adjustment relative to the hub’s shifting mechanism, gears still work properly, but the gear numbers on the twist shifter simply display an inaccurate indication of the selected gear. If the adjustment of the twist shifter is far out of proper adjustment, the shifter will not allow selection of the full range of gears.
The correct adjustment of the shifter cables is not really important for the functioning of the Speedhub, but it may influence the precision of the shifting process. Installing the cables too tightly causes shifting to require a great deal of effort. If the shifter cables are too lose, the gear shifting will feel imprecise.
It is possible to mount the twist shifter either left or right on the handlebar, even the direction of the twist up and down is at the installer/user’s option. To be able to read the gear number indicator right-side-up, the twist shifter must be installed on the right side of the handlebar.
The frame dropout spacing is according to the current standard of 135 mm. The hub weighs, depending on the version, between 1,700 g and 1,825 g. The hub contains 25 ml of oil which should be replaced once a year or after 5,000 km (manufacturer advice). The cog on the hub is made for standard-pitch derailleur-type bicycle chains 1/2″ x 3/32″ (ISO 082) and is offered with different numbers of teeth, like 13/15/16/17. The 15-, 16-, and 17-tooth cogs are reversible, offering double cog life once the cog is worn out in one direction.
[edit] Comparison with derailleur
[edit] Weight
To make a meaningful comparison we must take into account more than just the gear mechanisms themselves, although the contribution of the chain and spokes is small. Due to the symmetrical shape of the spoke flanges, the spoke tension is evenly distributed and is less than that of derailleur bike wheels, allowing fewer spokes with a smaller diameter to be used. The chain is shorter, the derailleur cassette is omitted and the spokes are shorter.
The weight can be compared with a high quality derailleur system (Shimano XT):
| Speedhub 500/14 CC-OEM | High quality derailleur system | ||||
|---|---|---|---|---|---|
|
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The Speedhub weighs about 0.5 kg more.
A new version (currently in development, with testing due to begin in 2009) will weigh 1400g, be 20% smaller and have a larger overall ratio of 580%.[1]
[edit] Advantages
- There is less wear on all parts, resulting in an almost entirely maintenance-free hub.
- The compact, closed design requires only a single chain wheel.
- The chain may be enclosed.
- Since no derailleur is involved, the chain is always in the optimal position regardless of the chosen gear.
- Because the hub is sealed from the elements, dirt and water do not interfere with its operation.
- The Speedhub permits symmetrical lacing of the spokes, which leads to less spoke strain and fewer breakages.
- Gears can be changed while the bicycle is stationary.
- Gears progress in constant steps.
[edit] Disadvantages
- High initial price. For a user covering long distances, total cost of ownership needs to take into account the cost of maintenance and replacing worn components, which may reduce the price disadvantage.
- When changing from the 7th to the 8th gear or viceversa under high pedalling pressure, the hub may change to the 14th gear.
- For the first few hundred kilometers, the friction of the hub seals may cause a forward movement of the pedals. The effect lessens over time.
- The unusual regularity of the 13 % gear stepping is sometimes uncomfortable for riders when the hub is in higher gears.
- The seals of the hub may leak when transporting the bicycle on a plane unless the oil is drained.
- Storing the bike in a horizontal position for a long period of time may cause the seals to leak.
- The twist shifter is not compatible with all handlebars. While there are some assembled handlebars available for racing bikes, there is not much variety.
[edit] Comparison with other hub gears
The Rohloff has a wider range of gears than any other hub gear available in early 2008, but the price is much higher.
[edit] Technical Data
| Frame spacing: | 135 mm |
| Spoke hole circle diameter: | 100 mm |
| Number of spoke: | 32 |
| Axle diameter at dropout: | 9,8 mm |
| Oil amount: | 25 ml |
| Sprocket thread: | M34 x 6 P6 |
| Chain line: | 54 mm (58 mm with 13-tooth cog) |
| Twist shifter angle per gear: | 21° |
| Shifter cable movement per gear: | 7,4 mm |
[edit] References
[edit] Information/Literature
- SPEEDHUB 500/14 “Owner’s Manual”, WS 2.13E 0605 (no ISBN) available in English, Dutch, France and German.
