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| *Vultures Knob>>>Road Bike |
Why is a large bike wheel better than a small one? |
I have been told that a large bike wheel is better from a rolling resistance point of view. I realise that from a comfort point of view a big wheel is better. Why should a big wheel be better. So far I have: Larger wheel = less rpm on the bearings for a given road speed Larger wheel = more rotation inertia, so more "flywheel effect" Larger wheel = easier and simpler to archive higher gear ratios Larger wheel = narrower for the same pressure Aside from the above, why should a big wheel be better than a small one? Primary things to consider: Larger wheels will travel further with every given revolution of the pedals, so you don't need as tall a gearing (you'll often see bigger front chainrings on road bikes with 20" wheels - check out the BikeFridays - they make SWEET folding bikes btw). That said, gearing ratios (especially on the high end) will end up making this a moot point. It's not harder to achieve high gear rations on a small-wheeled bike, it just a different gearing. Larger wheels are harder to accelerate for the same reason that they give you the flyweel effect and travel further - they're heavier and larger diameter - so more of the weight is further from the center. For the same reasons, larger wheels are more stable (it will take more force to get them to lean over). Larger wheels (assuming a 700c wheel here) are more standard and parts - tires, tubes, replacements, etc. will be more readily available. Larger wheels perform better through rough terrain (potholes would be your concern for a city bike), as the smaller wheels will hit the edges higher up on the wheel as a percentage of their size, so will be more jarring - trying rolling up a curb on a 20" wheel vs. a 700c wheel. If you are concerned about portability (considering folding bikes) smaller wheeled bikes will fold up smaller and be easier to tote around. That's why you really only see the smaller wheels on folding bikes. Much of these same arguments / discussions are happening in the mountain bike circles right now on 26" vs. 29" (roughly same size as 700c) wheels. I have owned / ridden both and now ride a 29" bike. I'm not sure on your bearing statement. Yes, the RPM will be higher, but I don't think that matters. The bearings will still last a LONG time, and are easy / cheap to replace. Source(s): Tons of answers to questions about big vs. small wheeled road bikes here: http://www.bikefriday.com/faq?question=a... I found it more reliable for rougher terrains, you don't see people going around in BMXs in the mountains, do you? im not sure about rolling resistance, but a 26" wheel, for example, will suck up a bump better than a 20" because of the greater surface area on the tire- it just rolls right over it, whereas a smaller wheel would fall into the ditch. |
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