Cycling with hub gears
A bike with hub gears – what does that mean?
Many people know this already: most city bikes are fitted with this type of transmission. The whole gear-changing mechanism is hidden within the hub of the back wheel, hence the name. The picture below shows an example of a hub gear, with a look inside as well.
What are the advantages of hub gears (compared to derailleur gearing)?
One of the most important differences – and also advantages – is that hub gears are as good as maintenance free, and the gear changing operates well in any weather. As we already mentioned, the gear-change mechanism is inside the rear hub, so water and dirt cannot reach it. So hub gears don’t have exposed derailleur mechanisms which need regular maintenance if they are to continue to work smoothly and consistently. Hub gears can also be easily combined with a closed chaincase, which shields the chain from water and dirt. And last but not least, a bike with hub gears has the advantage that you can change gear even when the bike is at a standstill. So if you’re stopped at the lights and have forgotten to change down, then with a hub gear it’s no problem: simply shift to a lower gear and you can set off again in comfort.
But bikes with hub gears also have their disadvantages, of course. Such bikes mostly have between 8 and 14 gears, distributed across a very wide ‘range’ (= the least and most distance that is covered with one turn of the pedals; or the difference in metres travelled per pedal turn between the highest and lowest gears). That’s because on a bike you need to be able to both tackle climbs and to travel fast with a headwind or downhill. This ‘range’ can be divided by a hub gear into between 8 and 14 steps. In practice, these steps are often quite large. Most bikes with derailleur gears, on the other hand, divide the range into 21, 27 or 30 steps (gears). So on a bike with derailleur gears you can adjust your pedalling tempo far more precisely to match the prevailing wind, terrain, loads carried etc. This in turn means that if for example you want to ride at 25 km/h at a particular pedalling speed, with a hub gear the chances are that you’ll find the pedalling either a little to heavy or a little too light. Another disadvantage is that if you have a puncture, with hub gears the rear wheel isn’t so easy to remove, so you have to fix the puncture with the wheel still on the bike.
Well-known hub gears include the Shimano Nexus hubs (not available via Koga Signature®). These are mostly used on city bikes. Shimano recently introduced a successor to the Nexus: the Alfine range. The first Alfine hub, the SG-S500, had just eight speeds, so the jumps between gears are still fairly large. The new Alfine SG-S700 has 11 speeds, so this no longer applies. Then there are bikes equipped with the Rohloff Speedhub 500/14, a 14-speed hub gear – the most impressive gear-change technology yet invented when it comes to hub gears.
The pros and cons of bikes with hub gears are as follows:
Pros:
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Almost maintenance free (even in winter)
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No grinding chains and shifting problems
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You can change gears while the bike is stationary
Cons:
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Puncture repairs are more difficult because the back wheel is harder to remove.
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Jumps between gears can be rather large (Alfine 8-speed).
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Weight
Bikes with derailleur gears
What are derailleur gears, and what advantages do they have?
Derailleur gears are a gear-changing system in which the chain can be shifted across the sprockets at the rear wheel, usually combined with a system of several (up to three) chainrings on the crankset. Up to 10 sprockets can be fitted side-by side at the back. The mechanisms near the sprockets or chainrings, which push or pull the chain across from one to another, are called derailleurs.
Who is it suited for?
It’s sports-oriented riders who overwhelmingly choose derailleur gears. They’re fitted on sporty touring bikes and trekking bikes etc. as well as on ‘pure’ sports machines such as racing or mountain bikes: you’ll find them on anything ridden by bike enthusiasts and professional athletes.
The most significant advantages of a derailleur system lie in the low overall weight of the transmission, its low drag and the number of gears available for the rider to choose from.
In comparison to the common hub gears with 8, 11 or 14 speeds, a derailleur system offers more speeds: for Koga this is 27 to 30. The difference between highest and lowest gears (the ‘range’) is divided up into smaller steps than on most hub gears. The effective number of transmissions for a 3x9 derailleur is usually not more than about 15 (for a 3x10 derailleur will this be added with one gear, so 16 in total), depending on the configuration of the chain wheels. Biggest advantage is that the incremental steps can be chosen as small as 6 or 7%, as opposed to 13 or 14% for the Rohloff or Alfine hub. So the cyclist has more choice while riding along to select the ideal gear for the prevailing conditions (speed, road surface, weather, wind, hills/mountains etc.). Because a hub gear has fewer speeds, the jumps between gears are much larger. Only the unique Rohloff hub gear is a positive exception with its incredible 14 speeds, which compete with the performance of a derailleur system, and for some riders match it.
A second advantage of derailleur gears is the low drag and low weight. A derailleur system has lower internal friction than a hub gear system, so that more of your work on the pedals is translated into speed, so it’s somewhat easier running. That said, a well run-in Rohloff or Alfine hub gear runs considerably easier than the cheaper hub gears. These advantages come into play particularly for sports riders, but also for passionate touring cyclists.
Thirdly, a derailleur transmission is an ‘open’ system, which can be easily maintained and adjusted. It’s much quicker to release and remove the rear wheel of a derailleur-equipped bike for maintenance or puncture-fixing than it is with a hub geared bike.
Furthermore, no closed chaincase will fit around derailleur gears, and for some riders this is a disadvantage: derailleur mechanisms, the chain and sprockets are all exposed to the elements. Rain and muck stick to the shifters, so a derailleur system must be regularly maintained. If you ride only in dry, fine weather, this is needed less frequently; if you ride in all weathers, more often.
For many bikes with derailleur gears (with the exception of racing bikes) chain guards are available, but only the best offer good protection. Good mudguards are also important, but unfortunately none of this can prevent water and muck building up.
A well-maintained bike will not be significantly affected by this, but their propensity to get dirty quickly remains a disadvantage of derailleur geared bikes. It helps to clean and dry a bike every so often after riding in the rain. Very dirty systems grind, fail to shift properly or at all, and run noticeably less easily.
In short: a bike with more gears offers a very pleasant ride. If as a touring or trekking cyclist you are planning a cycle tour over a long distance, with plenty of luggage, in hilly terrain or just with speed in mind, then you’ll be well served by a wider choice of gears, as with a derailleur system, the Alfine 11-speed or the Rohloff 14-speed. For racing cyclists a derailleur system goes without saying.
If you ride your bike all year on the flat, but also like to take it with you on holiday, then it would make sense to join the trend towards buying an all-round bike with plenty of gears.
The pros and cons of bikes with derailleur gears are as follows:
Pros:
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Many more gears, so more choice for any conditions
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Lower drag
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Easily accessible for maintenance and adjustment
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Low weight
Cons:
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Sensitive to correct adjustment
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Sensitive to dirt, requires maintenance (especially in winter)
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Not everyone needs all the gears.
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Derailleurs need re-adjusting every so often