At our school, Campus Safety has just confiscated dozens of abandoned bicycles, and "donated" them to "the Needy." As I am feeling needy, I had considered donating one to myself, and in examining the state of the art in cheap bike locks, I have decided that bike locks are redundant in many ways. Cable locks especially. A friend of mine almost got his bike donated, so I have it to examine at my leisure.

It occurs to me that cable locks are made of sturdy cables, reinforced with a plastic coating. Examining my friend's bicycle, I see four scaled down versions of such cables dangling around the front handlebars, as part of the bicycle's braking and gearing system. two of them eventually go around to the back. Why carry separate cables to lock up the bike with?

The sections of these control cables which run from the front portion of the bike to the controls on the handlebars must, by their nature, be flexible, and reinforced with a sheath in order to work at all. the controls themselves, in order to attach to the handlebars, must be equipped with a mechanism for opening, and closing.

Around the outside of the plastic sheath we already see on these cables, we will attach cut-resisting woven metal hosing, and another plastic sheath. This outer security cable will then be securely anchored to the frame of the bike, and to the braking/shifting controls.

Rather than the normal screw-down devices to hold these controls to the bike handlebars, we will a slightly specialized lock, specialized, because it is capable of being opened and closed with key or combination, and because it is capbable of gripping the handlebars securely.

Now, when you want to lock up your bike, you take the handle controls off, wrap these cables through the front wheel, around something sturdy, and lock them up... either back onto the handlebar, or to some other part of the bike.

Pros: Less weight for the average biker, as a cable lock no longer needs to be carried. More security for the paranoid biker, because the brake and gear controls are now part of a lock. Stealing the bike now probably involves destroying one's ability to brake and shift gears. Unlike currently available self-locking bikes, the bike can be locked as normal, securing the front wheel, which is popularly stolen, and preventing the bike from ending up flat on the sidewalk somewhere.

Cons: Servicing the hand-controls, and checking these portions of the cable may prove more difficult. Devising a secure method to anchor the sheath to the bike without interfering with the lines may be tough. Some folks are likely to start relying on just these devices for security, even in areas where more security is obviously necessary.

Clearly, control cable locking is not for everyone, but I suspect it might prove reasonably popular.
-- ye_river_xiv, Jun 12 2008

self-locking bike self-locking_20bike
Very similar. [phoenix, Jun 12 2008]

U-Lock Bike U-Lock_20Bike
Very similar as well. [phoenix, Jun 12 2008]

self-locking bike system http://www.ihpva.org/com/CyclicSystems/
Baked, but rather unpopular, it would seem. [ye_river_xiv, Jun 15 2008]

The quick-disconnects would have to be high-reliability, but [+] nonetheless.
-- 8th of 7, Jun 12 2008


Any decent bike has hydraulic brakes anyway, so this wouldn't always work.
-- Custardguts, Jun 12 2008


Ah, but it could; presuming the hydraulic hoses have steel-wire reinforcement in their walls, cutting them will be equally difficult, and will similarly disable the brakes.
-- 8th of 7, Jun 12 2008


And re-bleed the system everytime I unlock my bike?
-- Custardguts, Jun 12 2008


If these hydraulic breaks are anything like the non-hydraulic brakes I see on this bike, you can unlock the whole brake/gearing mechanism from off the handlebar. You'll have two cables on each "lock," but that shouldn't be too big of an issue.
-- ye_river_xiv, Jun 13 2008


BONE. I have to give you a [-] because those cables are sensitive. They require tight tolerances. Furthermore, taking them out of tension and then re-tensioning them is going to cause them to fatigue, and they are going to get longer/shorter after frequent tensioning/re-tensioning.
-- evilpenguin, Jun 13 2008


Bike cables require tight tolerances? What do you think all that brake lever travel is for? If you look at the average poorly-maintained clunker with 1/2" wobbles in the wheel rim and yet the brakes still work, you can forget about tight tolerances in these systems.

And tensioning and releasing the cables? If I might ask, how do you imagine that one turns the brakes on and off?
-- david_scothern, Jun 13 2008


Wow. When was the last time you rode a high end bicycle Sir? (DS)

The shift cables (specifically cables attached to rapid fire shimano shifters) are effected by corrosion on the cables. (corrosion occurs when the cable is exposed to air and it oxidizes, and this happens when you pull the cable out of its jacket) And try adjusting an old cable MORE THAN ONCE and your screwed. I know what I'm talking about, I ride a bike 12 miles to work every day. Thats24 a day. I maintain my bicycle myself and know how sensitive the cables are.

And about the brake cables... your incorrect. They are under tension at all times, just more when the brakes are applied.
-- evilpenguin, Jun 13 2008


I ride a recumbent trike, so my riding position is generally quite close to average bike rear wheel height; I've seen some terrible things (the bikes, primarily, although some of the riders looked pretty terrible too), vee-brakes opened right out to clear wheels that looked more like Pringles than anything else.

My upright's a few years old but hasn't seen much use bar a bit of commuting (stored outside at work); it's still on its original cables which have been adjusted a good few times without ill effect.

The gear cables, and the rear brake cable are only sheathed from handlebar to top tube and from seatpost to shifter; the cable run along the top tube is exposed, with no signs of corrosion. They're Shimano (Acera X if I remember rightly; nothing special) with not a hint of rust or fraying. A quick web search suggests that coated or stainless cables are available. Don't forget that in the past, cantilever brakes had a totally exposed "stirrup" cable linking the two arms; rust there wasn't inevitable either.

And yes, the brake cable is under light tension when it's off, enough to eliminate the slop that would be there otherwise. Releasing that marginal stress will, I guarantee, have a marginal impact (trust me, I've a little experience of designing gears, and the fatigue damage from minimal-to-nil-stress cycles is a lot less than max-to-min-stress cycles).

So, in summary: Tight tolerances - no. Serious damage from releasing cable - no. Corrosion - no.
-- david_scothern, Jun 14 2008


Well, corrosion, yes. Ill gladly take pictures of the cables I just replaced. (they are white in places) Perhaps you live in an area not so tough on cables, I dont know. Everyone I ride with has the same issues.

Back to the idea; I still don't like it. Do you DS? It seams more trouble designing quick-connects and a lock to work with the cables. And whats stoping the cables from getting kinked or bent when the are locking up the bike?
-- evilpenguin, Jun 14 2008


I think it would be hard to get sufficient strength without excessive weight, but that's not based on any calculations so I could easily be wrong. It looks like an elegant way to combine functions and minimise weight. Ordinary cable-locks don't seem to kink in use, due to their thickness, so I suggest that that might not have to be a problem. Provided there is enough cable length, it won't be in tension when it's being a lock, so sharp bends would be unlikely anyway - and unless it's always locked in the same way, it would be bent in a different place each time, so cumulative fatigue damage would take years.

A good quick-disconnect would be necessary, I agree. Mind you, brake cables usually have a lump at each end that slots into the lever. That disconnects immediately on demand; couldn't it be scaled up?
-- david_scothern, Jun 14 2008


With this discussion on warping as an issue, I'm not sure we understand each other. Maybe I did a crap job at explaining the idea. That's entirely possible, since I've never owned a bike of my own. Maybe I need to revise the explanation a bit.

As you're discussing this, I will revise the idea somewhat, both for clarity, and because your concerns are valid, and I neglected to consider a very simple improvement.

In case my revision is not clear enough though, my idea for using the brake and gearing lines as locks will apply only to the segments of these lines which go from the front of the bike to the handlebars. As this segment must flex in order to turn the front wheel, I assume the tolerances here are pretty high, comparatively.

With regards to thicker cables being a weight issue, the thickness of the new cables likely need not be much greater than before... rather, we will instead give added thickness to the sheath that the cables go into. Rather than a thin plastic sheath, we will place a double-walled plastic sheath, with a braided tube of thick wires inside it. this should approximate the weight and strength of a typical length of bicycle lock material.

I also suspect that providing a locking mechanism for the handles will be simpler than assumed. Currently, the entire break/gear shifting assemblies come off the handlebars by unscrewing two things. By replacing the unscrewing action with an unlocking action, it should be possible to use the whole thing without significantly damaging the breaking or gear shifting mechanisms... although making custom gear shift mechanisms in order to build the locks might cause some problems.
-- ye_river_xiv, Jun 15 2008


Why are bike stands not the locks, as well? Of course this limits you to parking your bike securely only at designated bike stands, but isn't that the point?
-- 4whom, Jun 16 2008



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