折疊車, 小徑車都比26吋或700C沒效率嗎 ?
看看甚麼"精實車" ?
http://nycewheels.com/compact-bikes.html
The term 'compact bike' simply refers to any bike with a smaller frame and tires that measure at 20" and under. Many folding bikes fall into this category.
The average person seems to be of the opinion that a full-sized bike with 26" or 700c wheels exhibits the preferred dimensions in a bike, and that compact bikes represent a sacrifice of sorts: the larger size and performance is exchanged for compact size and portability. Anyone that actually owns a compact bike, however, knows that a sacrifice is not being made. In fact, compact bikes present many real advantages over full-sized bikes.
Compact bikes maintain comfort and swiftness in riding, they are easy to get on and off of, they have increased handling, and they are easy to carry and store (especially folding bikes.)
Compact bikes allow for fast acceleration and superb steering, two important traits in a bike that one uses for commuting. With frequent starting and stopping in traffic, quick acceleration is important if one wants to flow seemlessly with the traffic as well as maintain a fast ride. Enhanced steering is even more important, as increased maneuverability means increased safety; the better your bike handles on the road, the better off you'll be. When it comes to commuting, full-sized bikes with larger wheel sizes can be cumbersome, slower to react, and incompatible with frequent changes of pace.
Folding bikes present even more advantages for the commuter, as they can be folded up and taken on public transportion, and into stores, buildings, and offices where conventional bikes aren't allowed. This is also a theft deterrent, as the owner doesn't have to lock up their bike outside; they can take their bike with them wherever they go.
Some additional advantages of smaller wheels: Small wheels climb inclines better due to the fact that they have a smaller diameter that needs to be rotated. Similarly, it is for this same reason that small wheels accelerate faster than larger wheels. As noted earlier, small wheels are more responsive and allow for more turning and steering control. In addition, when riding with others or with traffic, small wheels lend themselves to safer handling in closer quarters.
Despite all of the this, the myth that one compromises fit and performance for compact size still pervades among many casual riders. On the road compact and folding bikes alike exhibit high performance. The idea that a compact bike is slower than a conventional bike is incorrect. In fact, in many instances the opposite is true.
A folding bike was used to win a criterium race on the streets of Toronto where acceleration and maneuverability gave it an edge over conventional bikes. A folding bike was also used to set a human-powered vehicle speed record on an indoor track, behind a pace vehicle. A folding bike was ridden to a 3rd place victory at the world time trial championships.
Furthermore:
Tests have shown that up to 16 mp/h, the small wheel is more efficient than a big wheel. Between 16 and 33 mp/h there is little difference. Over 33 mp/h the gyroscopic effect of the big wheel makes it more effective. Most folks do not go over 33 mp/h. - Source: 1984 Olympic Men's Road Race Gold Medal winner, Alexi Grewal, in conversation.
So that this information fully sinks in, it should be noted that world class athletes average at 25 mp/h when competing in the Tour de France.
In terms of riders properly fittng themselves to a bike, folding bikes often come with more adjustable parts than conventional bikes. This means that folding bikes are more capable of accomodating a wider range of riders with different needs.
Despite the appearance of decreased size, (the frame itself is indeed smaller) the most important dimensions of most folding bikes are often equivalent to those of a full-sized bike. The distance between the center of the bottom bracket, the top of the seat, and handlebars is often comparable, if not exactly the same. It is this spacing ratio that largely determines if a bike fits a rider.
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