Without going into great details for the reasons behind it, people in The City travel everywhere by bicycle.

There are no stairs or lifts (elevators) in high rise buildings and no safe parking spaces for bikes at ground level.

To reach their home or office in a high-rise building, cyclists must cycle up the vertical face of the building and enter through a window.

I'm looking for a realistic way to implement this. Whatever the solution, it must not involve outside help, either human, animal or mechanical power. The bike rider must use only pedal-power and stay on the bike at all times while it is moving.

Here's what I have so far. The bike is only slightly modified. It has a spool mounted on the rear wheel that uses friction to climb the rope. It also has 'spikes' sticking out of the hubs of each wheel (these are described below).

The building has a rope hanging down and the cyclist winds it once around the spool. The rider then slots the spikes which are extensions of front and rear axles into two vertical slotted rails that extend up the whole building.

The cyclist then rides up the side of the building to the required height.

enter image description here


Are there any theoretical or engineering factors that make this setup impossible? Note: I am not asking whether the idea is sensible.

What, if anything, is bad about my design from an engineering point of view and (without investing in a lot of extra machinery) what could be improved?

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    $\begingroup$ Have you noticed that the cyclist is going to fall off the bike unless he's strapped in? And the bike itself will fall over backwards? Just checking. $\endgroup$ – WhatRoughBeast Dec 29 '18 at 18:06
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    $\begingroup$ The bike won't fall because of the spikes that are inserted in the grooves in the rails. The man is holding onto the handlebars for dear life. $\endgroup$ – chasly - supports Monica Dec 29 '18 at 18:11
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    $\begingroup$ @KerrAvon2055 - If I justified everything ahead of time, no-one would bother to read the question. I'll just point out that the Romans built the Colosseum with ladders, scaffolding and human powered machinery the-colosseum.net/images/macchine.jpg. $\endgroup$ – chasly - supports Monica Dec 29 '18 at 23:01
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    $\begingroup$ Another drawback - not all humans can hold their own body weight from their hands. The saddle and pedals provide support normally, but not in this orientation. Rider would end up danging from the handlebars by their hands, with no way to get back into a power position. $\endgroup$ – Criggie Dec 29 '18 at 23:29
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    $\begingroup$ how do you get furniture up? or anything else heavy or bulky. $\endgroup$ – ths Dec 30 '18 at 15:03

From a strictly practical angle, there are two problems I can see.

1: Coming back down. Would you go headfirst?

2: Body weight no longer useful to push against. This is a bigger problem. A bike is meant to support from below and the rider uses his/her own weight to press against. Pushing my leg against the pedal pushes the pedal down and my body up. At this angle. gravity does not pull me back down towards the bike. Tilting the bike 90 degrees means the rider can no longer push down using body weight.

The solution to both issues is to keep the bicycle aligned the same way it is on the ground. This video shows an invention that does exactly this, for much the same purposes you want.

bike elevator https://www.youtube.com/watch?v=TANb2p-HwlE

Thinking a little further, counterweights (as with an elevator) would be very useful here. They would slow descent and provide gravitation potential energy to aid ascent.

I worry that these prosaic considerations violate the rule of cool. What you want is for a bike rider to zoom up to the building and just keep going straight up. Ropes are fussy too. What you need is a harness clipping you to the seat so you can push down at any angle, and wheels that lock into a track and are held against it.

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    $\begingroup$ "What you want is for a bike rider to zoom up to the building and just keep going straight up.", Yes, that is the ideal. If you don't mind, I'll borrow that idea and maybe use it as a follow-up question. I think I'm nearly there because it would be easy to have the side rails make a curve from horizontal to vertical at the bottom. The tricky bit would be to automatically wind the rope around the spool. But, in any case the bike must be easily detachable and rideable over normal terrain as that is its main purpose. $\endgroup$ – chasly - supports Monica Dec 29 '18 at 17:36
  • $\begingroup$ One could use robust and purpose-built spokes to interlock with the rails for ascent, descent. The tire surface would be used normally for horizontal travel. $\endgroup$ – Willk Dec 29 '18 at 17:53
  • $\begingroup$ The problem with counterweights is that someone has to descend in order to raise the counterweight. That means that only one person can be 'at home' at a time. The problem with that video (and it is very impressive) is that the bike doesn't look like it could be used on ordinary roads without modification. I want a bike that can adapt quickly and easily or preferably instantaneously (as you suggest at the end of your answer) $\endgroup$ – chasly - supports Monica Dec 29 '18 at 21:00
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    $\begingroup$ /one person home at a time/ I assumed these high rises had multiple occupants coming and going. One big counterweight could serve them all. Once a month they would have a party on the roof and take turns hauling the thing all the way back to the top. $\endgroup$ – Willk Dec 29 '18 at 22:04
  • $\begingroup$ @ Willk - blah blah conservation of energy blah blah. Surely the effort to raise the darn thing will equal the energy they would have put out by simply riding up under their own power in the first place? $\endgroup$ – chasly - supports Monica Dec 29 '18 at 22:10

I think your biggest limitation is the human.

Your setup is meant to lift a cyclist of mass M at a certain velocity V directly against the pull of gravity.

Let's say your cyclist (and their bike) weighs 80 kg, that makes 800 N.

The world best cyclists, properly trained for the task, can produce a peak power of 2500 W for no more than 10 seconds, while during a climb on the mountains a more accurate power output is about 450 W.

This means that the climb velocity could be at best around 3 m/s for about 10 seconds, or 0.5 m/s for sustained effort. Not bad, you might think.

But we are talking about trained (and possibly doped) athletes. If we take a more normal person, the power output is lower. Let's take myself, not an athlete but at least used to cycle on long distances, I can produce about 120 W (extrapolated by timing a climb on a road of known length and slope). This means I would climb the building at 0.1 m/s. I can climb normal stairs at higher velocity and with less struggle.

If I had to choose, I would take the bike on my back and go for the stairs.

  • $\begingroup$ Thanks - I suspect that nearly everybody would end up as an athlete under this regime - unless of course they worked/lived on the ground floor. $\endgroup$ – chasly - supports Monica Dec 29 '18 at 17:21
  • $\begingroup$ P.S. There aren't any stairs. $\endgroup$ – chasly - supports Monica Dec 29 '18 at 18:13
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    $\begingroup$ I feel like it would be less exhausting to put the bike on your back and simply climb with the rope 'normally' $\endgroup$ – Andon Dec 29 '18 at 18:25
  • $\begingroup$ @andon climb rope normally, after tying the end to your bike. Then haul the bike up after you as a second action. $\endgroup$ – Criggie Dec 29 '18 at 23:31
  • $\begingroup$ This is an fundamentally mistaken analysis. With proper gearing (and the proposed hub sprockets would make that quite low) this is really not any worse than the stairs, at which you are probably overestimating your sustained capability. It's certainly a lot better than the awkwardness of carrying a bike up stairs. The downsides have more to do with mechanical complexity and dangers and experience of being high up on the outside of the building (doubly so in inclement weather). $\endgroup$ – Chris Stratton Dec 30 '18 at 1:15

Elevators that are chassis dynamometers

enter image description here

You ride your bike into an elevator and drive it until the front wheel straddles two rods, this holds your bike vertical. The full width of the elevator are two cylindrical drums. You stop with your rear wheel straddling both drums, clamp your front brake, and select your lowest gear.

Now, you pedal normally. Your rear wheel spins, the drums spin, the elevator climbs. The elevator is counterweighted for its empty weight + 1 rider, so you're not lifting the elevator, only overcoming friction.

The elevator has a shifter so you decide whether it ascends or descends from forward motion. It is also a one-way (think worm) drive that causes torque to travel one way only - you spinning the drums will move the elevator, but the elevator's motion cannot spin the drums.

The elevator is wide enough that 5-6 bicyclists could line up abreast, in which case each of you could use a higher gear and make the elevator go faster. Multiple people in an elevator will make it heavy (insufficiently counterweighted) by n-1 people, but you'll have help.

  • $\begingroup$ Your friction drive will probably not work well in practice, but the counterweight is clever, if tricky to safely manage. Worth noting that worms are only self-locking if friction dominates, which is most definitely not what you want. Low friction worms or screw threads are easily backdriven, as anyone with a 3d printer probably knows. But there are plenty of other ways to make a one-way clutch. $\endgroup$ – Chris Stratton Dec 30 '18 at 1:24
  • $\begingroup$ @ChrisStratton I can't really take credit for inventing the counterweight. A great many elevators work that way, not to mention, every garage door. $\endgroup$ – Harper - Reinstate Monica Dec 30 '18 at 1:57
  • $\begingroup$ The problem with pure counterweights is that on average, a certain number of people have to leave before an equal number can arrive. This would either make large meetings impossible or make a single person's travel impossible. $\endgroup$ – chasly - supports Monica Dec 30 '18 at 13:27

I don't know what will happen in a busy office building where dozens go either up or down in one minute. All is without distinguishing which rail is currently being used to go up or to go down. There must be a central control system to avoid vertical traffic jams, as well as avoiding someone from sliding down at full speed regardless of whether there is someone along the way.

You need:

  1. The bike seat must ba adjusted so you may lean to while going either way.

  2. Separate tracks for up and down.

  3. Built-in clamping device which connects the red cable.

  4. Good timing: exit the window when nobody passes by it

  5. Safety device: what if few people are on the same track and the cable snaps?

  6. Children climbing walls? Wheelchairs? Mothers with babies? A crippled grandmother? Can you help them?

  7. Black glasses (so you won't look down)

  8. Find a way to move in and out of the vertical position to your floor or street. That's too awkward.


  1. Pedal-powered platform. Has few seats so that each one pedals, not just one. A crank-wheel is mounted at each level so that you can bring the platform to you. The same platform must therefore move either way. The platform's weight is counteracted with counterweights. The cable below may be of different color than the one above it, so by looking at the cable, you know if the platform is above you or below you. Still, no central security control. You want to use it and someone else tries to get it at the same time. What to do?

  2. Stairs. Always worked, be it under fires or earthquakes or blackouts.

  • $\begingroup$ "Children climbing walls? Wheelchairs? Mothers with babies? A crippled grandmother? Can you help them?" They are housed in the ground floors of all the high rises. $\endgroup$ – chasly - supports Monica Dec 29 '18 at 18:20
  • $\begingroup$ P.S. As I originally stated there are no stairs. $\endgroup$ – chasly - supports Monica Dec 29 '18 at 19:06

Reality Check:


Rationale: Your scenario makes two competing and altercancelling claims. First, you state that people must ride their bikes up the side of a building in such a way that it must not involve outside help, either human or mechanical. Second, you depict an assistive mechanism constructed of simple machines. Your rails act as stationary levers keeping the bicycle in alignment. Your rope and friction spool act as a pulley system. Machines (apart from the human and the bicycle) count as outside help. Therefore, I'd say your premise fails the reality check.

If it weren't for your competing claims, I'd say the exact opposite. Bicycle powered elevators are a thing:

enter image description here

And while I find it odd that people would build high rise dwellings without stairs of any kind, that I'd chalk up to cultural oddity. There are primary world buildings (often monasteries) that can only be accessed by climbing up or being hoisted up the outside. And of course, Rapunzel's posh downtown Amsterdam flat could only be accessed in this fashion as well.

Rescue: You will need to figure out which basic element of your premise is more important: bicycles or no outside help. I believe that if you sacrificed the no outside help element, these people could easily construct elevators that accommodate and interface with a resident's bicycle.

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    $\begingroup$ By "no outside help" I simply mean no other humans, animals or powered machines are allowed. Machines that are powered entirely by the cyclist are fine. Note: The main purpose of the bike is transport in the normal way so that takes precedence. The bike cannot be specialised or permanently attached like the one in the picture. It has to be efficiently rideable over ordinary roads. $\endgroup$ – chasly - supports Monica Dec 29 '18 at 17:42
  • $\begingroup$ @chaslyfromUK --- I see! I think some judicious editing of the query might be in order! Understood about permanent fixture. Like I said, I am sure that such a culture could easily come up with an apparatus that allows residents to attach their own bikes to the lift. $\endgroup$ – elemtilas Dec 29 '18 at 19:50
  • $\begingroup$ Wouldn't wind also be a significant factor? $\endgroup$ – Underverse Dec 30 '18 at 10:13
  • $\begingroup$ @ Underverse - Cyclists are used to wind. However if you could somehow harness the wind to improve the system then that seems like a useful idea. $\endgroup$ – chasly - supports Monica Dec 30 '18 at 13:16

The bike could drive onto the elevator platform, clamp the front wheel in place & power the elevator through rollers under the back wheel. I'm thinking something similar to the setup used for testing cars without having them actually move. But it would be hopelessly inefficient and you'd have to make it so low geared that by the time you'd got to your apartment on the 20th floor it would be time to go out to work again.

Re: "how does this work" https://www.youtube.com/watch?v=WC5heoaQcGY&feature=youtu.be, that's clearly not a normal bike that could be ridden on roads. It doesn't have any wheels for a start.

  • $\begingroup$ The problem with a platform is that it is forever ending up in the wrong place. That's why I want each cyclist to be able to move independently. A platform would be useless during the rush hour but a line of independent cyclists could climb the wall one after another. The reason for "How does this work?" was to contradict the idea of it taking hours to move one floor. There's nothing to say that that machine couldn't have wheels as well as all the other gearing although it would be an almighty faff to unattach it for ordinary riding. $\endgroup$ – chasly - supports Monica Dec 30 '18 at 17:17

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