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Motorcycle Brake Lights - Tail Lights
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Conversion Chart for Brake Light Bulbs
There are several motorcycle tail light and brake light bulb types which are
interchangeable.
Note that these are bulbs that have a low/high filament; i.e., one
filament is "on" all the time as the running light, and the
other filament comes on as the brake light.
If your motorcycle takes a 21/5W bulb for the brake/taillight
combination, you will see that there are
alternative bulbs that offer different (better?) levels of lighting.
The most
interesting aspect of this is that some of these alternative bulbs are
available in "long life" versions, which are designed to last
longer for "heavy duty" use where vibration is anticipated,
such as can be experienced on motorcycles.
Why should you use a different bulb?
Note that the "Diff (%)" column in the table below shows the difference in Watts
between the low (running light) bulb power (as an indicator of
brightness) and the brake light power. This is important because a
greater difference between the running light and the brake light to
following vehicles will help increase their awareness that you are
coming to a stop.
For example, if a motorcycle's running light is 20 Watts, and the brake
light is 25 Watts, the difference would be so minimal that following
drivers might not notice when the brake lights engage.
This is why I'm a big believer in the rule "one task, one
bulb". The difference between zero output and, say, 25 Watts,
using a single filament bulb, is much greater and will be more
noticeable than that of a dual-filament. But, I supposed to save
space (and money), motorcycle manufacturers seem stuck on the idea of
having one bulb perform multiple tasks.
My feeling is that you should find a bulb that is a compromise between
three things: brightness, greatest difference in brightness between the
running light and the brake light, and longevity.
The 2397 does it
for me as a replacement bulb for my Triumph Thunderbird Sport's 21/5W
for one reason: it offers the same differential as the 21/5W, but has at
least 5 times the life expectancy. Also, the 2397's are noticeably
brighter than the 21/5W's when the brake light filaments are lighted
(the T-Bird takes two 2397 bulbs).
Note: Since this article was first
published, there have been advances in LED lighting technology.
See the wBW
articles on LED light
replacement and LED
brake lights - tail lights.
| |
Bulb |
Filament |
Volts |
Watts |
Diff
(%) |
Amps |
CP |
Lumens |
Life
(hrs) |
| Dimmest |
2057 |
Low |
14.0 |
6.86 |
74.5 |
0.49 |
2 |
25 |
5000 |
| |
|
High |
12.8 |
26.88 |
2.10 |
32 |
402 |
1200 |
| 1034 |
Low |
14.0 |
8.26 |
64.2 |
0.59 |
3 |
|
5000 |
| |
High |
12.8 |
23.04 |
1.80 |
32 |
|
200 |
| 1157 |
Low |
14.0 |
8.26 |
69.3 |
0.59 |
3 |
38 |
5000 |
| |
High |
12.8 |
26.88 |
2.10 |
32 |
402 |
1200 |
| 2397 |
Low |
14.0 |
6.72 |
76.5 |
0.48 |
2 |
38 |
5000 |
| |
High |
12.8 |
28.54 |
2.23 |
40 |
503 |
400 |
| Brightest |
2357 |
Low |
14.0 |
8.26 |
71.1 |
0.59 |
3 |
|
5000 |
| |
|
High |
12.8 |
28.54 |
2.23 |
40 |
|
400 |
| For
reference, here are the specifications for a 21/5W bulb: |
| 21/5W |
Low |
13.5 |
5.9 |
76.5 |
0.44 |
2.8 |
35 |
1000 |
| |
High |
13.5 |
25.1 |
1.86 |
35 |
440 |
250 |
|
CP = Candle Power. Lumens are a more accurate way of
describing "brightness". This data is from one
manufacturer's bulb specification guide; other bulbs may differ
slightly, but they should be very close. The bulbs are listed
in order from dimmest to brightest.
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