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I have been thinking of a design for a standard bicycle monorail. I don't have the resources to prototype it right now so I would like to bounce the design off the community.

Basically thinking of a half cylinder track that is larger diameter than a bicycle wheel. For a prototype I was considering ripping 2 inch pvc in half for the straight sections. In application people could ride a standard department store quality bike on to the track at an enterance and off at an exit without any modifications or reconfigurations to their bicycle.

My biggest concern is balance stability on the track (even on a straight section not considering corners). On a normal path the operator corrects from a disturbance by gyroscopic precession (and resultant turning) of the front wheel. The track will limit this but will provide an elevation change toward the outside of the track that may assist. Thoughts? Any prior art you know of? Thanks!

I don't want to debate the usefulness of the idea, but just so everyone is in the know, there are three potential benefits:

  1. Lower cost for longer distance bicycle path infastructure.
  2. Lower rolling resistance than a normal flat path.
  3. Lower cost for snow removal and maintenance.
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    $\begingroup$ In other words, you want to make a bike only sunken rail-path type system...? First thing comes to mind are hazards in the track..rocks and debris could be dangerous and not easily avoided while in a track. Water would need to be drained as well $\endgroup$ – GisMofx Dec 5 '17 at 2:16
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    $\begingroup$ How is one person going to pass another? Think before going so far afield. $\endgroup$ – Carl Witthoft Dec 5 '17 at 18:34
  • $\begingroup$ @GisMofx, I was thinking of the track being above grade in non cross traffic areas and having drainage gutters in cross traffic areas. The track itself can have 6mm holes to drain water and sand. Occasional large debris would have to be avoided by slowing to a stop and dismounting. $\endgroup$ – ericnutsch Dec 5 '17 at 19:33
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    $\begingroup$ @Carl Witthoft, potentialy set a speed minimum and or periodically switch to a standard bike path to permit passing. $\endgroup$ – ericnutsch Dec 5 '17 at 19:36
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it would be nearly impossible to stay balanced on a bike with the steering constrained like that.

Edit/ Not sure the really warrants a dissertation on bicycle stability, but briefly when riding you are in a state of meta-stable equilibrium. If your center of gravity moves slightly off center you would tend to tip over. The corrective action, which makes the activity possible, is that you counter steer. This is so natural that you don't even think about it, but if you put your wheels in a groove so no steering is possible you will learn in a hurry.

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    $\begingroup$ This probably should be a comment, but if you can elaborate and discuss how a bicycle actually steers (oversteering counter to direction, etc), it'd be good. $\endgroup$ – Carl Witthoft Dec 5 '17 at 18:34
  • $\begingroup$ Yeah I am aware of this issue, but like Carl said, I'm looking to better understand and design the control dynamics here. $\endgroup$ – ericnutsch Dec 5 '17 at 19:38
  • $\begingroup$ I like your cost considerations but stability is what worries me. You could try it out, find some area like driving polygon or cement playground, set your tubes in circular path and try it. I think the worst of it is psihology, feeling of stability and safety, not the actual stability. if you decide to do testing use intermediate driver, not someone who does e.g. acrobatics or marathons but also not someone who desn't ride bicycle frequently. $\endgroup$ – Katarina Dec 8 '17 at 0:04
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    $\begingroup$ This is correct - if you can't turn you can't balance. If you try and balance using your weight only, the tyre will scrub on the inside of the track and climb out, or oscillate between sides. Try cycling along tram tracks to learn how bad it is - you'll fall and break something. $\endgroup$ – Criggie Dec 16 '17 at 8:22

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