TECHNOLOGY IN DETAIL
GEAR STEPS 1-14
Here, we explain in detail the function of the individual gears of the SPEEDHUB. For all who would like to know exactly what is going on.
Our gear unit consists of three in line interconnected planetary gear assemblies #1, #2 and #3. Input is delivered by the sprocket, which is screwed to the driver which connects to gear assembly #1. The planetary gear assemblies #1 and #2 are identical, except that they are laterally reversed, sharing together the planet carrier (1-2). A total of seven gears are produced by these first two assemblies. The further connection of gear assembly #3, which serves as a reduction gear, doubles the gear count to 14. The output drive is delivered from planet carrier #3 to the hub shell via 9 nylon coupling pins located in specially machined pockets.
In all texts and illustrations, parts corresponding to their affiliation with gear assemblies #1, #2 or #3, can be identified by the supplement (1), (2) or (3)..
PLANETARY GEAR SYSTEM
A planetary transmission system (or Epicyclic system as it is also known), consists normally of a centrally pivoted sun gear, a ring gear and several planet gears which rotate between these.
This assembly concept explains the term planetary transmission, as the planet gears rotate around the sun gear as in the astronomical sense the planets rotate around our sun.
The advantage of a planetary transmission is determined by load distribution over multiple planet gears. It is thereby possible to transfer high torques utilizing a compact design.
Gear assembly 1 and gear assembly 2 of the Rohloff SPEEDHUB 500/14 have two selectable sun gears. The first gear step of the stepped planet gears engages with sun gear #1. The second gear step engages with sun gear #2. With sun gear 1 or 2 coupled to the axle,or the coupling of sun gear 1 with the ring gear, three ratio variations are achievable with each gear assembly.
The mechanical efficiency and consequently the related losses incurred by the Rohloff SPEEDHUB 500/14 are entirely comparable with that of a derailleur system.
The losses incurred in a derailleur system result from frictional losses generated at the bottom bracket, chain, cassette and hub bearings. The green area within the diagram shows the range of the efficiency of a derailleur system. Depending on the chosen chain ring- sprocket combination, cross chainline and wear situation the losses of efficiency add up to 1.5 - 5%.
The losses incurred with the Rohloff SPEED-HUB 500/14 result from frictional losses generated at the bottom bracket, chain and gearhub. The yellow line shows the efficiency of the Rohloff SPEEDHUB 500/14 relative to the chosen gear. The overall average frictional loss within the Rohloff SPEEDHUB 500/14 ranges between 1.5 - 5%. Consequently, the Rohloff SPEEDHUB 500/14 is the optimum choice for sportive cycling.
As a comparison the grey area in the diagram shows the range of efficiency for 7- and 8-speed internal gear hubs. Characteristic for those is the significant fall of working efficiency in higher and lower gears.
GEAR RANGE COMPARISON
The right gear system plays a very important role in making bike riding fun.
The difference between the largest and the smallest gears (range of gears) and the size of the increases between them play a large part in deciding which riding situation the gear system has been tailored to (e.g. high speed racing). The size of the increases between gears will decide how smoothly the flow is from gear to gear. Tuning the range of gears, the number of gears and the increases between each of these gears will eventually define the riding fun.
The shifting between gears in all riding situations (including whilst stationary) must then be made as light and intuitive as posible in order to maximise the riding fun. If the range of gears lies over 500% and the increase between these gears lies under 15% but remains evenly spaced out, then the sports rider (as well as the hobby rider) has the ability to change gears at the precise moment when needed, regardless of the current riding conditions and without changing the comfortable crank rotation speed. This is only possible with the high performance hub Rohloff SPEEDHUB 500/14.
The diagram below shows a comparison between a 27-speed derailleur gear system and the Rohloff SPEEDHUB 500/14. There is no difference between the range of gears and the range of effective gears. Next to this is the optimum, evenly increased speeds of the Rohloff SPEEDHUB 500/14. Impossible for the derailleur gear system is the shifting speed and the possibility of shifting through all gears with just one shifter whilst stationary or whilst pedaling. Just like the derailleur system, the range of gears can be taylored to the riders individual wishes whether that be for a faster or a slower riding style.
Presented here, is an exploded view of the Rohloff SPEEDHUB 500/14. Clicking on the image on the right will enlarge the display.
Selecting the correct gear system is a decisive factor for cycling enjoyment. The ratio between the lowest and highest gears (the overall range) determines the degree of incline that can be ridden and the maximum achievable speed on the plain. The difference between two neighbouring gears (the increment) determines the comfort and ease with which your speed and momentum can be maintained over different terrains.
When the overall range, gear count and the increments conform, riding enjoyment increases as the gear system is effortless and intuitive to use in all situations, including whilst stationary.
The high shifting speed and effortless gear selection through one simple twist of a shifter (regardless of whether the cyclist is stationary) is simply unachieveable for a derrailleur system.
MODULAR PARTS SYSTEM
The various Rohloff SPEEDHUB 500/14 models are based upon a modular system.
There are three axle types (Quick release CC, threaded axles TS and an A12 axle is constructed for frames fitted with dropouts which accept 12 thru-axle systems) presenting a base for the 14 speed bicycle hub transmission.
The Rohloff SPEEDHUB 500/14 can be optimized through the use of different peripheral components for mounting into almost every type of bicycle frame available. One must simply selecting and combine the correct transmission components mentioned below.
When the Rohloff SPEEDHUB 500/14 is built up into a 32 or 36 spoke wheel, it is considerably more robust than the common 36 spoke wheels. The stability is actually almost identical to that of a 48 spoke tandem wheel.
The spoke flanges of the Rohloff SPEEDHUB 500/14 are constructed symmetrically. This allows all spokes to be at the same angle on both sides of the finished wheel which in turn leads to a much stronger wheel due to the evenly distributed spoke tension. To build a strong wheel, the spokes must be tensioned to a minimum of 1000N (with inflated tire). The rear wheels of normal derailleur systems need to be dished to accommodate the room required by the cassette. This creates a huge difference in spoke tension. The tension on the dished side is usually considerably higher (over 1200N) and this can lead to problems with the spoke nipples sitting correctly within their seats in the rim (see the MTB comparison underneath, the pretension in the 8-speed cassette here is just 600N).
Due to the increased diameter of the hub flanges and PCD of the Rohloff SPEEDHUB 500/14, the spokes need cross only two times but do so at roughly the same angle as a three cross lacing pattern on smaller flanged hubs. There is less load on the spokes because of the large flange PCD diameter and the hub flange is subjected to lower forces because these spokes pull further away from the axle center creating a better lever to pull the wheel around (torque = force x lever length).
The comparison below shows the maximum spoke loads (the numbers in brackets are the pretensioned forces of spokes after lacing):
The figures for the 8-speed tandem wheel are better than those of the solo MTB wheel due to the fact that the spokes are not at such steep angles and there are 48 of them regardless of the fact that the tandem has to transport two cyclists. Even here though, the Rohloff SPEEDHUB 500/14 wheel with 1206N compared to 1409N is still the better option.
Further Information can be found in the Owners' Manual.