20" vs. 26" bikes? Pros, cons? Any considerable top speed loss on a 20"?

Question

I am thinking on buying a Dahon bike but I am unable to decide between a 20"-wheeler and a 26" one. Im thinking about de Dahon Jetstream XP vs. Dahon Matrix 2008 (24 gears both). There could also be other alternatives but I am really interested in the drive comfort and speed. It will be mainly a commuter bike so 5 miles per day on asphalt and in the city. Thanks.

Answer 1

114 gear inches does not mean that you will travel 114 inches per crankarm revolution. To determine how far you travel per crankarm revolution, you'd need to multiply the theoretical diameter of the wheel (gear inches) by 3.14. Gear inches come from the old Highwheeler days, where bicycles were sized by their front wheel diameter. A 48'' was faster than a 36'', a 52'' was faster than a 48'', etc. How this translates to modern bicycle gearing is that a bicycle with a 32 tooth chainring, 16 tooth cog, and 26'' wheel (52 gear inches) would translate to a highwheel bike with a 52'' wheel, thus 114 gear inches would be the equivalent of a highwheel bike with a 114'' front wheel, which of course would be impossible to ride. Anyways, in regards to 20'' vs 26'', it's possible to compensate the 20'' with gears high enough to give it a "top end" gear comparable to a 26'' wheeled bike. However, there are only so many chainring/cassette combinations, so eventually one would reach a point where the only way to get a higher gear would be to get a bigger wheel. A smaller wheel accelarates faster than a larger wheel (assuming that they are geared equally). A larger wheel rolls over bumps better, and is more efficient. A small wheel is stronger, but has less ability to absorb shock. A larger diameter wheel (which uses a larger diameter tire) gives you a larger volume of air, which is an important consideration for off-pavement cycling, as you can run a tire with a larger volume of air at a lower pressure than a smaller tire, with less risk of a pinch flat. I'd go with the 26'', but that's just my opinion.

Answer 2

This same issue is bought up when comparing 26" and 29" mtn bike rims. As you have noted the difference in how far per revolution a tire rolls a simple change in gear ratios will solve this problem if the manufacture didn't. Next is the difference in the way they roll, a 20" will be able to accelerate faster due to it's lower mass, however a 26" will roll better due to it's larger radius.

Answer 3

26” wheels are intended for riders that want a very comfortable ride with the stability of wide mountain bike tires. The smaller wheel size (compared to a hybrid or road bike), combined with the wider tire, makes 26" bikes very good for gravel paths, light trails, and pavement riding.

I'd say your best off going for the 26" bike.

I also think that 26" wheels would gain more speed than that of 20", something to do with the time it takes the wheel to perform one whole spin I think.

Answer 4

400-700 price range won't get you much of a laptop. You get a laptop because you want portability. If you don't need portability get a desktop. With a desktop whatever you get now you can easily expand on. For example, most gamers by a top on video card (think 400-700 for that card alone). The point is that when you need more speed later it will be cheaper to expand your desktop than buy a new laptop.