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While designing a bicycle what are the designing factors to be considered to increase the friction to give more efficiency to the cycle.And what are the other factors that can be considered while designing.my interest is to design a modified bicycle to improve efficiency and decrease man power

closed as unclear what you're asking by Deleted User, Móż, alex, Gary.Ray Jan 26 '16 at 14:26

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    Iced-up road has zero friction, see what happens to the cyclist! – Carel Jan 25 '16 at 18:45
  • Static friction or rolling resistance ? Cos they happen at the same place but are totally different. – Criggie Jan 25 '16 at 19:24
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    like your question "design a shaft drive for me" you haven't given us enough information to be able to help you. What friction? If you can edit your question to give more information, and specifically what you have tried, what you're trying to achieve and what research you've done to find an answer, it's likely we'd vote to re-open your question. But as it is I don't think we can answer it. Right now "riding on ice has very little friction" is correct and useless. – Móż Jan 25 '16 at 22:10
  • i have edited the question so can you please answer it – ytfhgv ikj Jan 26 '16 at 17:08
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    You have made the question even more nonsensical. Tire traction (within normal bounds) has virtually nothing to do with bike efficiency & necessary power. – Daniel R Hicks Jan 26 '16 at 19:18
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Reducing friction (or grip in layman's terms) would cause your wheel to simply spin in circles when you pedal and you would fall down. Increased friction between the tire and the riding surface is the goal of nearly every tire manufacturer.

You could easily coat your tire in oil to accomplish the lower friction you are talking about.

  • Comments are not for extended discussion; this conversation has been moved to chat. – Gary.Ray Jan 26 '16 at 14:29
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What you want to minimize (within reason) is "drag" or "rolling resistance" caused by the tires in contact with the road. This is a function of tire width, tire pressure, tread design, and the characteristics of the rubber. Plus, of course, the characteristics of the road.

Generally, higher pressure reduces contact area (for a given weight) and hence rolling resistance. Smooth tires produce fewer losses than lugged tires, and hard rubber fewer losses than a softer rubber. (But at some point the tire is harder than the road and no additional gains can be made.)

Further, having tires that are too hard can reduce overall (human-operated) bike efficiency because vibrations are transmitted through the tires and bike to the rider's body, where they are dissipated as heat (and fatigue). Ideally, the tires are soft enough to absorb moderate bumps, but the rubber and tread are designed such that very little energy is absorbed, but rather "reflected" back to the road as the bumps go the opposite direction.

  • Higher pressures reduce deformation, which reduces rolling resistance. Wider tires at the same pressure actually have lower rolling resistance due to a differently shaped, but roughly similar contact area. – Deleted User Jan 25 '16 at 23:19
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The ONLY thing bike design has to do with the friction between the tyre and the road is weight related, assuming tyre design does not count as part of bike design.

Heavier design of bike = more friction, Lighter design of bike = less friction.

I for one would not consider "designing a bicycle" in the context of this question to be designing the tyres, any more than I would consider it to be designing the drive terrain. As far as I understood it and I may be wrong it is reasonable to consider "design a bicycle" in the above question to be frame design + component selection.

However if the question actually means, as Mσᶎ believes, the design of any part of a bike then following should be done:

  1. You should design tyres (or tyreless wheels) as thin and hard as possible (maybe out of wurtzite boron nitride) for absolute minimum contact area. Then you should (after inventing a method to do so) coat those wheels with Cerflon for minimum coefficient of friction.
  2. You should design and integrate into your bike a device to perfectly smooth the path ahead of you and coat it in an extremely hard substance which is then in turn coated with Cerflon.

Diamond and poly(1,1,2,2-tetrafluoroethylene) would be reasonable substitutes for wurtzite boron nitride and Cerflon respectively.

  • Hi and welcome to bicycles.stackexchange. You answer seems confused, you emphasise that only weight has any effect, then list three other things that have an effect. I think your answer would be improved by a bit of editing. You might also find it helpful to think about friction in the bearings. There are a number of answers in this site that contain the answer to this, if you search for power and rolling resistance those keywords should help. Also the user "R. Chang". – Móż Jan 25 '16 at 22:06
  • @ Mσᶎ No, I am not confused. I answer "how to reduce friction between tyre and road via bike design". Then I answer "what are the other factors that can be considered for designing". These are the two questions he actually asked. Then I reinterpret his question to be about rolling resistance and answer how bike design can affect it. Finally I make 3 points telling him how to better go about affecting rolling resistance. Bearings and freewheels are not strictly speaking rolling resistance and thus were not mentioned. – Purr Jan 25 '16 at 22:59
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    Tyres are part of the bike, and designing them is very much part of bicycle design. And the question doesn't mention rolling resistance, only "friction between the tyre and road". Since you want to get pedantic about it, your answer doesn't relate to that question because it only talks about rolling resistance, not friction. To reduce friction you'd want a hard, smooth, large tyre. Like one of the plastic drift trike wheels. – Móż Jan 25 '16 at 23:03
  • @Mσᶎ edited my answer to only answer his question. – Purr Jan 25 '16 at 23:07
  • @purr - nope. By checking the edit history I see you've edited your main answer 12 times as of this moment. Noone can edit your comments but you. Your first comment was edited twice by you, Moz' comment was edited once by them, and your last statement was edited once by you. – Criggie Jan 26 '16 at 3:15
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I know it is not much more than a link only answer but this is a very good discussion.

Narrow and higher pressure is good. But on a ruff surface too much pressure can cause bounce and more resistance. Generally, smooth treads roll better than coarse treads.

Wiki Rolling Resistance

Rolling resistance, sometimes called rolling friction or rolling drag

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    Down vote care to comment? What is wrong? – paparazzo Jan 25 '16 at 18:36
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    This does not answer the question. Your answer is in regards to rolling resistance and , additionally, contains incomplete information regarding the relationship of tire width to rolling resistance. – Deleted User Jan 25 '16 at 18:42
  • @SuspendedUser You really think the OP is asking about traction? Your answer is incomplete in regards to traction versus width. What ever. – paparazzo Jan 25 '16 at 18:46
  • While this link may answer the question, it is better to include the essential parts of the answer here and provide the link for reference. Link-only answers can become invalid if the linked page changes. - From Review – Móż Jan 25 '16 at 22:01
  • @Mσᶎ It does include the essential parts of the link – paparazzo Jan 25 '16 at 22:51

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