i want to know about the complete design and dimensions of the shaft and suggest me to give more efficiency to the bicycle
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Always remember, cycling technology is driven by reducing the weight of the bicycle. Having a shaft that weighs half the weight of your bicycle is something you should avoid.
These are consideration when building a shaft:
- Weight: 500gram to 1kg heavier than normal chain drive is ok, 1-2kg kg is not bad, but over 2kg+ is terrible.
- Strength: must be able to withstand torque of at least 200 N.m, in practice it could be 3-4 times the minimum. Apart from the torque, you need to analyse the hoop strength. For example, the shaft should not break under normal drop/horizontal impact. I cannot tell you how thick and how big the shaft should be, because different materials will result in different design.
- Compatibility: how you integrate the shaft driven into a normal frame. Bevel gear is a good start. Design a bevel gear appropriate for cycling is the next. Don't integrate a heavy bevel gear, which was designed for car/industrial machine, into your shaft. Design it yourself, shave as much weight as possible, but keep it as strong as possible.
- Gearing: Start with single gear, or integrated gear hub. It is the easiest way. If you are using single gear, having a bicycle that is more than 11 kg is undesirable. Also check gearing ratio. Design a pinion (part of bevel gear) that could be threaded into the single gear wheel. (Last time I remember it is some imperial 1.375x24 tpi or something close to that)
- Torque: for the same weight, shaft-drive is at great disadvantage comparing to chain-drive regarding maximum deliverable torque. So, again consider gearing appropriately so that the torque is as small as possible.
Aiming to build a shaft driven bicycle for efficiency is the wrong direction. Efficiency improvements of shaft over chain driven in bicycle is negligible. Not to mention, shaft driven is overshadowed by an (un)established market regarding gearing on bicycle.
Advantages of shaft driven:
- Low maintenance
- Better durability
- Slightly better efficiency over time, since it requires less maintenance
- Can be driven with high-torque, very good for some of the electric mid-drive motor
Disadvantages of shaft driven
- Heavy. However, with the cost of carbon fiber being driven down, a carbon shaft designed for bicycle might just be light and economical just as a chain driven.
- Expensive when repair/replace, again, market is the keyword
Here's some prior art for you to search out...
Reader "Unclemiltie" reminded me that America's first billionaire, John D. Rockefeller, loved to ride his bike, and was still riding in his 80s. It's a little bit ironic that he made his fortune at the helm of what was then the world's biggest oil company, which greatly enabled America's love affair with the automobile. This Library of Congress photo shows him posing with his shaft-drive Columbia bicycle.
Unfortunately he's standing in front of the interesting bits. However we can see that there is no chainring. There are also no brakes, so his bike was likely a fixed single-speed. To me this implies a toothed ring gear at the front and at the back, with a fixed drive shaft between them. As a plus it would pedal backwards as well as forwards, but no gearing. Lubrication of the gears is likely an oil bath, like a car's differential.