Bicycle Technology: Lighting and other Accessories

This section is devoted to the equipment that can be used on the bicycle but is not essential for its operation at all times. Some machines are devoid of all such accessories, while others are generously equipped with items ranging from luggage racks to lights, water bottles, fenders and computers. Although there is little doubt that the naked bike is the more enjoyable one to ride, circumstances often dictate a need for one accessory or another.

As regards selection and maintenance of accessories, the most important advice is to select only items that can be firmly attached to the bike and are in them selves structurally sound. Racks that swing back and forth, bend under the load or slip down the frame are dangerous and frustrating. Other items only work well if they are themselves properly designed and constructed. Basically, everything that is not attached in at least two points will tend to come loose, although very light items may be clamped less firmly — but only if they are held very close to the member they are attached to.

Simply clamped items are likely to slip down along the tubes of the frame if they are not specially secured. This problem can be eliminated by first sticking a patch from the tire patch kit around the location where the accessory will be mounted, as shown in Fig. 14.2. Use rubber solution on the tube just as though you were patching a tube. It will prevent not only slip, but also damage to the frame. The same effect cannot be achieved by means of sell-adhesive tape (e.g. handlebar tape), since this tends to slip because the adhesive never hardens enough to form a permanent bond.

For accessories that should be easily removed from the bike, be it because they are not usually needed or to avoid theft, it is often possible to make some kind of quick-release attachment. In cases where this is not practical, it is still possible to ease installation or removal by means of e.g. wing bolts, which may be made by soldering a sizeable washer in the slot of a screw bolt per Fig. 14.1, if not commercially available in the right size.

14.1. Home-made wing bolt for removable accessory installation.

14.2. Installation of provisional clamp around frame tube or stay.

14.3. The author at work testing lighting systems — during a lighthearted interlude. No better use could be found for the two leg lights at the side of his head.

Lighting Systems

Of all the accessories, lighting equipment is probably the most important: lighting defects (or missing lights) are the only technical defects that cause a significant percentage of all serious bicycle accidents. The major problem is that many cyclists are so scared of riding in the dark that they swear never to do it, and consequently feel no need to install lights. Invariably, they get caught in situations where lights are necessary — and risk it anyway. Others use their lights so rarely that they fail to maintain them properly.

Basically, there are two different types of lighting systems: generator (or dynamo) and battery powered. In addition, there are hybrid systems that combine elements of the two systems, as well as different battery- operated variants, namely with the battery either built in the individual lights or centrally located and connected to the lights by means of wiring. Finally, reflectors can fulfill certain lighting functions and can be considered as secondary lighting systems. Below, each of these systems will be treated separately.

Generator Lighting

Fig. 14.4. shows a typical generator lighting system. It consists of an electric generator, or dynamo, which generates electricity when it contacts a moving part of the wheel, connected to a headlight and a tail light. One pole of the electric circuit is connected by means of insulated electric wires, while the metal of the bike acts as the second pole via mass contacts between the frame and the mounting hardware of generator and lights. The old-style incandescent bulbs in headlight and tail light have a rather limited life expectancy (on the order of 50 - 100 hours of operation) and are usually simple to replace. Newer LEDs last virtually forever.

14.4. Alignment of generator

14.5. Roller generator

Most generators work by means of a roller that contacts the side of the tire. To minimize slip, wear and resistance, it is critically important to align the center line through the generator perfectly with the wheel axle. In the other plane, the roller should lie flat on the tire sidewall when engaged and retract about 1cm (3/8”) when disengaged. These criteria are illustrated in Fig. 14.4.

The best place to mount the conventional generator is on the LH side of the rear wheel, pointing forward from the LH seat stay. In this position, it is not likely to get caught in the spokes if it should come loose, nor does it get in the way or obstruct the rider’s view of the rear derailleur. The attachment by means of a lug brazed on to the frame tube is far preferable to the usual clamping method — something to keep in mind when specifying a custom-built frame. An alternative is the so- called block generator which forms one unit with the headlight. It is installed on the front fork and has the advantage of easy removability, especially if it is not connected with a rear light. Instead of a generator- powered rear light, you can use either a battery light or a really big amber or red reflector.

The generator converts mechanical energy into electrical energy. Unfortunately, it usually does this rather inefficiently. Whereas an efficiency of 70% should be easy to achieve, most dynamos do not surpass 20—30%, meaning that 10—15 watts of mechanical output has to be produced by the rider to keep a 3 watt system operating. To put it into perspective — about 20—30% of the output required to keep a bike moving at 16km/h (10mph).

A few special generators are somewhat more efficient than the run-of-the-mill, although even these waste more energy than they should. The best conventional dynamo appears to be the Swiss Nordlicht generator with a rubber roller that runs on the rim rather than the tire. Even more efficient are some roller dynamos that are installed under the bottom bracket to run off the top (rather than the side) of the tire, as shown in Fig. 14.5 and 14.10. Amongst these, the Union model was tested most favorably. Most roller generators do not fit on a racing frame with short chainstays and in rainy weather, they tend to slip (a bungee cord between the roller arm and the bottom bracket increase the pressure of the roller on the tire enough to prevent slip.

Mechanical efficiency is not the only critical factor. Equally important is the voltage and power curve, which defines the relationship between speed on the one hand and voltage and (electrical) power output on the other. Ideally, the output should increase rapidly at low speeds to achieve adequate lighting even at a modest riding speed, after which it should level off and remain relatively constant so the bulbs do not burn out due to excess voltage at higher speeds. The optimal curve is shown in Fig. 14.7. In this graph, the non- shaded area defines the range within which the output voltage should remain. The graph is based on a 6-volt system.

Although there are a few 12-volt systems on the market, all of them are characterized by such a disastrous output curve that bulbs burn through at the drop of a hat when cycling at speeds exceeding 16km/h (10mph). These 12-volt systems usually pro duce a nominal 6watt of output, compared to the 3 watt generated by most 6-volt systems. Generally, they have separate contacts for a 12-volt headlight and a 6- volt rear light.

Bulb, Headlight and Rear Light

The most efficient light bulbs are those filled with a halogen gas (usually krypton). These not only produce up to 50% more light than conventional bulbs, they don’t dim over time, when regular bulbs rapidly get black as the filament material sublimates and condenses on the inside of the glass. Halogen bulbs require different fittings, so the headlight in which they are used must be designed differently. They also burn hotter and are more sensitive to excess voltage. The bulb should not be touched with bare hands since that would etch the special glass — replace these bulbs with the aid of a tissue.

Amongst the headlights, the best models are those that bundle the light most accurately and evenly over an area wide enough to light up the width of the traffic lane when aimed about 6 - 10m (20—33 feet) ahead of the bike. An additional narrow beam, aimed further ahead, may be useful as an early warning system, but a brightly lit area close to the bike is more critical under most circumstances. Large headlights tend to be more satisfactory, with the additional advantage that they make the bike more visible to others coming towards the bike or approaching from a side road. For the same reasons, a relatively high mounting position (on the handlebars in preference to lower down) lights up the road better, throws less confusing shadows, and maximizes visibility. Although on a road bike, narrow beam lights should turn with the handlebars, cycling off-road calls for a wide-beam light that does not move with the handlebars — preferably supplemented by an additional light mounted on the handlebars.

The rear light should preferably be mounted relatively high. If a luggage rack is used, the best location is just underneath the luggage platform. On a bike without luggage rack, the optimum position is just under the seat. If you use a saddlebag, which would obstruct it there, you have to mount the light on one of the rear stays, again making sure it does not get obstructed. One location that is not recommended is on a plastic or aluminum fender, since vibrations causes fatigue cracking. Sooner or later, the attachment bolt simply breaks out of the fender.

There is a dramatic difference between the light output and visibility of various rear lights. Invariably, the larger ones are much more visible than smaller models. Those that contain a built-in parabolic reflector behind the bulb are more visible than those without, and amber lights are more visible than red ones, and flashing lights are both more visible and much more economic in terms of battery life. Recently, very com pact rear lights have been introduced that use flashing LED’s instead of bulbs.

14.6 and 14.7. Left: Conventional (single) wiring diagram for typical generator lighting system. Right: Electrical criteria for generator performance (see text for explanation).

14.8. Double wiring for generator lights

14.9. Conventional rear-wheel-drive generator system from Union.

14.10. Sanyo Dynapower roller generator

14.11. Block generator for front wheel

14.12. Designer dream. This integrated unit of head light, generator and front brake is not very practical

14.13. ESGE rechargeable system

Generator Lighting Defects

When a generator system fails, it is only possible to establish what went wrong if you follow a very systematic approach. After all, this system comprises a large number of mutually connected components. Fig. 14.14 shows a simplified logic diagram for this. But don’t let system rule over logic: ask yourself what is the most likely cause under the given circumstances. Thus, when it is raining or snowing, generator slip is more likely the cause than in dry weather — so that is the point to start: make sure the generator is aligned properly and increase contact pressure by bending in the attachment.

14.14. Generator lighting troubleshooting chart. This simple logic diagram will help you search for and eliminate causes of lighting malfunction in a systematic manner.

Reflectors

In the US, and a rapidly increasing number of other countries, a whole plethora of reflectors is currently prescribed — in some countries only when the bike is sold, in others when the bike is operated. Although the latter approach seems more logical, it is by no means favorable, because the assumption on which this legislation is based is totally unscientific.

The only reflector that is of any use is the one mounted in the rear facing straight back (although pedal reflectors may be a useful supplement, on account of their movement). All other reflectors do not serve any purpose that is not better met by other forms of lighting equipment. The two things to keep in mind with reflectors — more correctly called retro-reflectors (Fig 14.15) — is that they are only visible to those whose head lights are directly aimed at them, and that they do not help the cyclist see any better, whereas lights are visible from a wide arc, and help the cyclist see his way and anything in his path.

Only a headlight can protect the cyclist to the front from running into obstacles and make him visible to approaching or crossing drivers and pedestrians. An addition white reflector does not help one bit (if the headlight does not work, the cyclist should not be riding in the dark).

To traffic approaching from side roads ahead, again only the headlight is visible. Spoke reflectors and reflecting tire sidewalls remain invisible to those who could endanger the cyclist, since the crossing driver’s headlight is not aimed at them until it is too late.

From the rear, either a rear light or a reflector aimed straight back gives adequate protection. All drivers approaching the cyclist have headlights that are aimed straight at the reflector, which lights up brightly.

14.15. Retro-reflection compared to mirroring principle. Mirror (light not usually returned to source)

14.16. Loss of reflective surface due to angled reflector surfaces. Divided reflector 2/3 wasted area; Plain reflector (reflection fully visible from important range)

Totally inept is the concept of dividing the rear reflector into three smaller panels aimed under angles offset to the left and the right, as shown in Fig 14.16. Drivers whose lights are aimed at the bike under this angle are not on a collision course with the cyclist, so do not need to see him: they will cross the point where the cyclist is now — but the cyclist will be gone by then.

There are a few points to consider in the selection and maintenance of reflectors. In the first place, bigger is better: larger reflectors are more visible than smaller ones, all else being equal. Secondly, lighter colored reflectors are more visible than darker ones. Amber reflects about twice as much of the light as red. Consequently, amber reflectors should be selected for the rear wherever it is legal to do so (the argument that it might be confused for a side-reflector is invalid, be cause lateral movement distinguishes side reflectors unambiguously from those mounted in the front or the rear).

As for maintenance, reflectors only do their job properly when they are kept clean: wash them regularly with plenty of water. However, if water should leak inside the reflector, it condenses on the inside, making the reflector virtually blind. For this reason, a cracked or broken reflector should be replaced immediately. To check a reflector’s operation, aim a light at it from a distance of 10m (33ft), observing from a point close to the light source whether the reflector appears to light up brightly. But if your eye is too far from the straight path between the light source and the reflector, you will not notice the retro-reflection.

14.17 and 14.18. Above: Ever-Ready battery rear light Below: Gran rechargeable frame-mounted light.

Battery Lighting

Although most of what was said above under Bulb,

Headlight and Rear Light applies to battery lighting as much as it does to generator lights, there are a number of considerations that are specific to battery lighting systems. All of them have the advantages of being independent from the rider’s efforts: it’s no more work to cycle with than without light and the light stays equally bright at any speed. They are all rather expensive to operate and require regular attention to make sure the batteries are adequately charged for the riding ahead.

The simplest form of battery lighting consists of separate units for headlight and rear light, each containing its own batteries. This type is used almost universally for bicycle lighting in Great Britain (whereas the rest of Europe uses mainly generator lighting). Nothing wrong with this relatively simple type of light, except that it rarely has quite enough output. Its advantages include easy removability and relatively low purchase arid operating cost.

The best lights of this kind are those made by Chloride, sold under the name Ever-Ready in the UK and US. These units run on two large D-cell batteries each and are designed to light up a rather narrow spot quite far away, while still being highly visible due to their large lens. Although even this best of regular battery lights is marginal for the front, the rear light is brighter than anything else I’ve ever seen. Unfortunately, the mounting hardware supplied with these lights, does not keep the lights aimed properly.

The other form of battery lighting is a central battery wired up to a separate head light and rear light. These tend to be very expensive and not all of them give either more light or better service than the simpler and cheaper integrated battery lights. Designed correctly, they can have a bright light that is optimally selected to put the light where it is needed, possibly even with an option of high and low beam for different situations.

Batteries

The batteries are a special problem for all forms of battery lighting. Regular dry cell batteries have an output characteristic that is highly life-dependent: when new, the output is about 1 .5V per cell, which gradually falls to an average of 1.2V, eventually dwindling to nothing. Consequently, the light is bright at first, settles at an average value for some time and then drops off further.

The output of a new battery provides a light that is twice as bright as the average value, while in the end it gives off only a tiny fraction of the average. Bulbs are selected to give the rated output at the average value of 1.2V per cell (thus, a bulb for a two-cell unit should be rated at 2.4V, rather than 3V, although the cells are nominally quoted at 1.5V each).

Rechargeable batteries are available in the form of nickel-cadmium (NiCad), NiMH (Nickel Metal Hydride) and Li-Ion cells that are fully interchangeable with regular dry cells, or as lead-acid gel batteries suitable only for separate mounting. Both models have entirely different characteristics, as is apparent from Fig. 14.19. The output of a NiCad cell stays relatively constant at 1.2V and the light remains almost equally bright up to the (shorter) overall charge life, but suddenly dims without warning. This is one reason to carry fully charged spares if you use NiCads.

The correct way to maintain NiCad batteries is to run them down completely before recharging them. If they are recharged before they are fully drained, they will soon lose their ability to hold a charge. If this happens, they can usually be revitalized by fully charging and discharging them five times. They have a limited shelf life and should be depleted and recharged at least once a month — and discarded when they don’t hold a charge.

The other form of relatively common rechargeable battery is the lead-acid gel type. Unlike NiCads, these are not available in sizes and shapes that are inter changeable with regular dry cells, usually being rectangular. They do hold more charge and can be recharged before they are fully run down — in fact, they should never be completely discharged. This type lends itself best as a central battery wired to separate light units.

14.19. Comparison of battery characteristics.

14.20. Flashlight attached to the front fork. Although it shines a long way, the beam is not wide enough for safe cycling under most circumstances.

Luggage Racks (Panniers)

These accessories should be regarded as load-carrying components of the bicycle. Consequently, they should be designed, constructed and attached with the same considerations in mind as the major components of the bike. The support stays should run straight to their mounting points and must be firmly attached. Additional stays should be arranged so that the load is distributed and the design is triangulated in such a way that lateral rigidity is achieved. The illustrations show satisfactory racks for front and rear and a stay arrangement that achieves adequate lateral rigidity.

As important as the construction of the racks themselves is their arrangement on the bike. From a stability standpoint, the most favorable load distribution is as shown in Fig. 14.22. Thus, the front rack should be designed so that the load can be carried low and in line with the steering axis (i.e. just behind the front wheel axle). The rear rack should carry the load as far forward as possible — attempts to lower the load invariably also require it to be placed further back for heel clearance, which deteriorates the bike’s handling.

Probably the finest material for racks is tubular steel with a diameter of at least 8mm. Since this kind of construction is rather work-intensive, with lots of brazed joints, most racks are made of aluminum alloy rod. It should have a diameter of at least 6mm, while racks made of steel rod may use material that is about 4.5mm in diameter. Important details are a restraint on the top platform to stop the load from pushing against the rear brake, and stays that are arranged so that the pannier bags cannot move sideways against the wheel.

14.21 and 14.22. Eclipse rack; Stability test for distribution of weight (mass) in panniers or luggage.

14.23. Checking for stability of loading

14.24. Pannier / Luggage rack types

Fenders

To make easily removable fenders, it is possible to attach the stays to the drop-outs and fork-ends by means of wing bolts and with the clips with which they are attached to the brake mounting bolts held between double nuts. Use two (thin) locknuts instead of the single nut provided, and tighten both nuts even when the rack is not installed, so the brake is held adequately, which could not be done with only one thin nut.

Fenders, or mud guards, are useful items in most climates. Though it may not be as much fun to ride in the rain as it is in sunshine, it is a lot more endurable on a bike with fenders. After all, you cannot dictate the weather, but you can prepare for it. Suitable fenders for lightweight bikes are made of plastic or aluminum, each attached to the bike with stays made of steel rod and clips as shown in Fig. 14.25 and 14.26.

14.25. Attachment of stay to fork

14.26. Attachment of stay to fender

Chain Guard

Chain guards are not “in” (i.e., hip or popular). And even those that are used, generally don’t serve their purpose. However, good chain-guards that protect both the chain and the rider’s clothing do exist and are installed on just about every utility bicycle in some countries. They usually limit you to the use of bikes without derailleur gearing, although the Dutch importer of the Japanese Miyata bicycles and Shimano components has dug out some components that actually make it possible to use derailleur gearing with a fully enclosed chain guard.

14.27. Fully enclosing ABS chain guard as used on most Dutch utility bikes.

Kick Stand

More correctly known as prop stand outside the US, this device is typically only used on simple bicycles. Al though few are any good, some models work better than the others. The Japanese model that is attached on the rear stays close to the rear wheel axle is much more effective than the more common type that is attached just behind the bottom bracket. Besides, it does not get in the way while wheeling the bike backwards, as the conventional kick stand does.

Another interesting model is the two-legged version. Its advantage is that the bicycle can be balanced on it so that it does not lean over. With this model, either the rear wheel or the front wheel can be raised off the ground to work on the bike. The same maintenance purpose can be achieved by means of a $15 shop stand — nothing to install on the bike, but handy at home.

14.28. Rear-wheel-mounted kickstand

Child Seat

Not your everyday accessory perhaps, but a rather important one if you have a young child. They exist for installation in the front and the rear. The former type is only suitable for mountain bikes and other machines with flat handlebars and a rather long top tube, since on other models the child would interfere with hand ling and balancing the bike (or the other way round). These must be attached to the top tube, not to any part connected with the steering system. Children above the age of 4 are generally too big to be carried in the front. Bigger children are better carried in the rear than in the front.

The type for installation in the rear comes in two versions: for independent installation and for attachment to a luggage rack. Only the very strongest and rigid racks lend themselves to the installation of a seat. Models for direct attachment to the bike are more common in the US, while luggage-rack mounted models are often seen in Europe. Any child seat should meet the following criteria:

- Very sturdy, rigid construction and attachment to the bike

- Integral support for the child’s back and sides

- Seat belt to tie the child in

- Adequate support and protection for the feet to stop them from getting caught in the spokes, a frequent cause of bicycle-related child injury.

A final word of warning on the subject: don’t ever leave a child in the seat when you are not holding the bike — always take the child out of the seat first, before you do anything else.

Bicycle Computer

Today, this is about the most common bicycle accessory, and these things are getting both cleverer and smaller every year. Select one that has the minimum number of knobs consistent with the functions you de sire. Follow the manufacturer’s instructions for installation, calibration and maintenance. Generally, it must be calibrated for the wheel size, measured accurately between the road and the center of the loaded bike. It pays to look for a model that is advertised as being waterproof and comes with a guarantee to back up this claim. If it is not, put a plastic bag over it in the rain and always take it off the bike when transporting it.

Pump

There are two types of bicycle pump. For workshop use, I suggest using a big floor pump with an integrated pressure gauge, making sure it has a connector for the kind of valves on your bike (Schrader and Presta valves each require a different nipple, while Woods, or Dunlop, valves can be inflated with the same connector as the one designed for Presta valves). For on-the-road use, get a frame-mounted pump that can be installed along one of the bike’s frame tubes, again with the appropriate connection for the valves on your bike. With their relatively small volume, frame pumps should be of the kind without connector hose, since too much air gets trapped in the hose to allow adequate inflation of high-pressure tires.

If the pump does not work, it is due to a leak at either the washer in the head of the pump or the plunger. First try to close up the washer in the head by turning the end cap a little tighter. If it is a leak in the plunger, disassemble the pump, grease, soften and knead the plunger and reassemble it again. It may be necessary to install a new washer or plunger.

In recent years, the pump is being edged out by devices with CO2 cartridges. Though small and handy, they are rather wasteful, especially considering their volume is inadequate to inflate a set of mountain bike tires.

14.29. Pump head and seal washer

14.30. Detail of pump showing the plunger with its cup-shaped end.

Lock

Unfortunately, the lock is one of the most essential accessories. And even the best are inadequate to keep pace with the developing means to crack them. As a minimum, lock the frame and both wheels together with a fixed object big enough so it cannot be lifted off. The familiar U-locks, though not completely fool-proof, are generally the most satisfactory. Use a bracket to attach it to the top tube or the seat tube of the frame.

By way of maintenance, it may occasionally be necessary to lubricate the lock. Do that very sparingly, using one or two drops of light oil on the key and on each of the points where the shackle disappears into the lock housing. Then open and close the lock a few times and wipe off any excess lubricant.

14.31. Kryptonite lock mounting bracket.

Other Accessories

In addition to the ones listed above, other items are introduced from time to time, some of which hardly war rant mention due to their simplicity. Most of these gadgets are taken off the market as quickly as they were introduced, since few are really as practical or well-conceived as may at first appear. One useful accessory is a bike trailer. Providing the attachment mechanism with which the trailer is connected with the bike is well designed, it can be very useful for carrying bulky items ranging from camping gear to kids.