We supply 4 types of bicycle and flashlight bulbs:

LED, Halogen, Krypton, Vacuum

A LED BULBS are the most efficient light source and provide whiter, clearer illumination at much lower power consumption, compared with filament bulbs. Nicelice LED bulbs utilise high performance multi-led emitters and have a lifetime of over 30,000 hours.

The very long LED life contrasts with miniature filament bulbs, which typically have a life of 25-200 hours, depending on the design and type. The lowest voltage filament bulbs have the lowest life.

B HALOGEN FILAMENT BULBS contain a technically advanced mixture of active and inert gases. The active component re-cycles tungsten from the glass back onto the filament, enabling the use of a hotter, brighter filament. They are the ultimate filament bulbs. The glass is thicker than Krypton and Vacuum bulbs, and is hardened to produce a mechanically stronger bulb. Halogen bulbs are available in the widest power range and they provide good colour rendering in applications such as slide viewers and inspection lamps. Halogen bulbs with push-in and screw-cap bases are suitable for rough and demanding conditions. They have been successfully shock tested at 40G in the axial and lateral planes for emergency lighting in military aircraft.

C KRYPTON FILAMENT BULBS contain pure inert gas which allows the filaments to run at a higher temperature than Vacuum bulbs, emit a whiter light, and enables enhanced visibility for a given power consumption compared to Vacuum bulbs.

VACUUM FILAMENT BULBS are the basic type which are best for low power lighting where high intensity light is not required. They are the lowest cost, but because the filaments operate at a relatively low temperature, only a moderate light quality may be achieved. This can be a shortcoming in cycle headlamps and flashlights if a penetrating beam is required.

We supply 7 common light bulb bases:

Bi-pin G2.5 = T5 5mm diameter (16mm glass length)
Bi-pin G4 = 8mm diameter (24mm glass length)
MR11-C = 35mm diameter Reflector and Cover Glass.  27.3 - 27.7mm front to back (excluding pins), rim thickness 1.9-2.4mm. Pins typically 7mm, Pin Housing 14.5mm x 9.5mm (slight taper).
Push-in P13.5s = Flanged Pre-focus - 'PR / KPR / HS3', barrel diameter 9.2mm, with flange "V" notch. Overall length 27.5-30.5mm
Screw-cap E10 = E10 [MES] G31/2 , thread diameter 9.5mm. Overall length 27.5-30.5mm
Bi-pin bulbs for Mini-Maglite® and Solitaire (Nicelite LED)
CNC extra bright bulbs for Maglite® C & D cell (Nicelite LED)

Please email if you require more precise size for (4) or (5). Dimensions vary due to production in different factories.

If you are unsure of the exact bulb you require, refer to the Bicycle Bulb Guide or Flashlight Bulb Guide tables. There are pictures of the different bulb bases on the LED, Halogen, Krypton, and Vacuum pages.


HIGHER BRIGHTNESS: To increase brightness please consult the upgrade bulbs listed in the Bicycle Bulb Guide or Flashlight Bulb Guide. If planning other upgrades, please be aware that plastic parts designed for a certain power level ('W' column) may not tolerate the higher temperature of a significantly more powerful bulb. In addition, avoid leaving lights switched on in a location with little airflow where they may overheat. When upgrading to a Nicelite LED bulb, there will not be a problem with overheating, as Nicelite bulbs use lower power, producing less heat while emitting more light.

BEAM FOCUS: The beam from a screw-cap bulb can often be manually focused by adjusting the amount the bulb is screwed into the holder, if the centre contact is sprung. The beam focus is pre-set with flanged push-in (PR / HS3), bi-pin and MR11 bulbs.

BULB GLASS:  We do not supply quartz glass so there is no danger of cracking if the glass is touched, however for best illumination keep bulb glass completely clean.

BATTERY RUN-TIME: Battery discharge time is directly proportional to the cell capacity, and inversely proportional to the amps (A) rating of the bulb.

To calculate the approximate run-time, divide the capacity of one cell in amp-hours (Ah) by the amp (A) rating of the bulb. Eg the expected run-time with a GH157 bulb (4.8V 0.5A) powered by 4 fully charged 2.2Ah cells is 2.2 divided by 0.5 = 4.4 hours (4 hours and 24 minutes).

The capacity of rechargeable cells is usually indicated on the label. Alkaline cells have the following approximate capacities: LR03/AAA = 1.1Ah (up to 0.3A max. bulb), LR6/AA = 2.5Ah (up to 0.6A max. bulb), LR14/C = 8Ah (up to 0.9A max. bulb), LR20/D = 16.5Ah (up to 1.1A max. bulb).

NICELITE LED bulbs have automatically variable amps (A), depending on the voltage being supplied. To calculate the amps, divide the watts rating of the bulb (W) by the voltage you will be using. Eg if the Nicelite bulb is rated at 1W, and if you are using a 6V battery, then the amps will be 1 divided by 6 = 0.17A. You may need to estimate an average voltage.

VOLTAGE: For lights powered by disposable zinc chloride or alkaline manganese, and NiCd or NiMH rechargeable batteries, the rated filament bulb voltage is lower than the fully charged or new battery voltage. This is because the battery voltage under load is lower. Please see the cell quantities column in the bulb lists.

Nicelite LED bulbs have internal power regulators, and all work within a voltage range, making selection much easier. Nicelite bulbs can be moved from one light to another in the same voltage range. The power regulator maintains brightness as battery voltage declines, or as road speed varies with dynamo bulbs.

Our MR11-C bulbs are designed to be very bright and white when run at the rated 6V. Unlike some bulbs on the market, it is not necessary to "over-volt".

Cycle Dynamos can produce excessive voltage and cause bulbs to fail prematurely. Modern dynamos are generally better regulated, and systems designed for Halogen bulbs usually have an electronic voltage regulator (more).

CONTACTS: Electrical contact between components, even in brand new lights, can present high resistance and impair the brightness or produce flickering. The cause can be a build up of oxide on the surfaces. If you suspect that brightness is lower than it should be, metal polish or domestic cream cleaner can be used to clean all accessible electrical contacts in the circuit, such as between cells, the contact strips or springs, and the bulb holder contacts. The cleaned surfaces can be given a light coating of oil via a small brush or cotton swab to inhibit re-oxidation. Alternatively a professional electrical cleaner can be used, which will contain oxide removers and also leave a protective layer. It is important not to use abrasive which might remove any surface plating. Take care not to get any substance on the reflector.


1. Many cycle generators produce excess voltage at high speed, over-loading the bulbs. When one bulb fails, voltage rises significantly, over-loading the remaining bulb even at lower speeds. When replacing a Halogen headlamp bulb, it's a good idea to also replace the GV601 low cost tail light bulb (if fitted - see 2).

2. Excess voltage can also occur if electrical contact is lost, perhaps momentarily, with one of the lights. We recommend checking the electrical connections, and connecting the earth return terminals where fitted, rather than relying on the mounting bolts for connection to the frame, as the connection through the bolts can be affected by corrosion over time.

3. It is fairly common to power just the headlamp from the dynamo, and use an independent battery powered LED tail light. In this case it is preferable to fit a 3W headlamp bulb rather than the standard 2.4W, because virtually all bicycle dynamos are designed to supply 3W. Due to the unavailability of 6V 3W Halogen bulbs, it would be necessary to use Krypton GK6050 or GK6055. Alternatively Nicelite LED bulbs can be used with a suitable regulator.

A common exception is the Sturmey Archer Dynohub which has a 2W output, with bulbs providing a 1.8W load. For Dynohub bulbs, please see the Bicycle Bulb Guide, and Nicelite LED Bulbs.

4. Output from a generator driven from the rim or tyre is not affected by wheel diameter, eg unless the tyre is skidding, the tread of the tyre is always moving at road speed. The fact that a small wheel has a higher rate of rotation is not relevant. Therefore at any speed, the power from a rim/tyre generator is the same whether the wheel is standard or small diameter.

5. Output from a hub generator is higher at all speeds when fitted in a small wheel, which can seriously over-load the bulb(s) and any electronics (such as LED standlights) unless a suitable regulator is fitted. In this situation there may be sufficient dynamo power to operate a 3W headlamp bulb and a tail light, therefore reducing the tendency to over-load the bulbs.

It appears from reports coming in, that some headlamps are having their factory-fitted regulators burnt out by the high excess power of hub generators at high speed. We have therefore designed the XGEN5 with heavy duty 5W-rated components to control this excess power, as shown in the Dynamo Regulator section. XGEN5 has been proved effective in controlling hub generators and allows the use of brighter, whiter Nicelite LED Bulbs .

6. We supply external Dynamo Regulators.

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