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I just bought a giant escape 2 and have been using it to go to work. When is time to come back home is already dark and I'm planning to get a light. Asked about one in nearby bike shop and they suggested me the following (https://www.qoo10.sg/item/GENUINE-GIANT-ZOOM-LIGHT-BICYCLE-LIGHT-HEADLIGHT-LIGHT-TORCH/531628737):

enter image description here

Comparing it to the models from Giant website https://www.giant-bicycles.com/us/lights it seems to be on the cheap side.

I also noticed they classify lights as "to be seen" (cheap, i.e. hl100, hl200) and "to see" (expensive, i.e. hl500).

So which one would you advise me to get? If hl100 is not enough perhaps hl200 is ok, or I better go with the hl500? In principle my intent is to use the light to see.

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  • If you want the light to see with, you should buy one the manufacturer advises (HL500). It depends on the the amount of lighting on the roads/trails, how fast your ride, how well you know the roads/trails and to some extent, how skilled you - to many variable for us to be able to offer an answer of any value.
    – mattnz
    Nov 22, 2020 at 4:13
  • Please only get a road-legal light which doesn’t blind oncoming traffic and adjust it properly. Usually that means no round lights with a circular symmetry beam. From the picture of the headlight you’ve linked it could be okay.
    – Michael
    Nov 22, 2020 at 8:53
  • Ive just got a great head mounted everreadylight from B&M Stores only a few pounds too...As were ever you look it illuminates.A great quality cheap removable device.Oh yeah and included batteries too..
    – kim
    Nov 22, 2020 at 16:10

2 Answers 2

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So you're riding at night - are the routes lit by streetlights? Or are you riding in pitch darkness?

The former would recommend two "be seen" lights for the front and two for the rear, and the latter would require at least one Seeing light and a backup for the front and still two on the rear.

I'd strongly recommend adding some combination of spoke reflectors, reflective sidewalls, and reflective clothing to go along with your active lighting. DOT tape is available in appropriate colours and costs nothing to operate.

Be aware you do not need a Giant-brand of light on your Giant branded bike. The only time such a thing is needed is if there are built in connectors to an internal wiring harness or similar. Otherwise you're free to fit whatever lights you like.

I personally run two completely different front lights plus a head lamp. The main one has an "hours remaining" readout which tells me if I can make it home before it goes flat. Likewise I have several rear lights each with their own power, so they're less likely to all go out at once.

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The brightness of lights is measured in lumens.

The numbers there refer to the maximum brightness (full power).

Cheap lights will have lower maximum brightness and smaller batteries.

So HL100 = 100 lumens maximum. It has a 420 mAh lithium polymer battery, which has an average voltage of 3.7V.

The HL500 = 500 lumens maximum. It has a 2000 mAh battery, with the same nominal voltage.

Thus the brightness is exactly five times greater and the battery is almost five times larger.

Generally the simplest bicycle light that's not tiny like the HL100 just looks like a standard small flashlight (torch). Here's a popular cheap flashlight, the Convoy S2+, which sells for around $15 and weighs 76g

enter image description here

Said flashlight is available in four versions: 3x7135 (1.05A), 4x7135 (1.4A), 6x7135 (2.1A), 8x7135 (2.8A). The 7135 is the name of the power chip, and the max current is in amperes.

Nearly all flashlights sold take 18650 cells, which cost around $5, and commercially vary between 2Ah and 3.5Ah capacity.

There are small differences between LED/power driver efficiency, but largely if you use the same sized battery and run the light at the same current then you will get a similar light output.

So for example, this 'HL 1100' light has a 3.5Ah battery

https://www.giant-bicycles.com/us/recon-hl-1100

and runs down in 1.5 hours, which suggests approx. 2.3A current draw.

This 'HL 500' light has a 2Ah battery

https://www.giant-bicycles.com/us/recon-hl500-2019

which lasts 2 hours, for 1A current draw.

Anyway, generally when buying a bike light we would look at:

  • battery capacity - 2Ah is a little 'cheap' to me, in that a quality 3Ah cell is quite affordable, e.g.:

https://18650.uk/product/samsung-30q-18650-battery/

so rather than use a $5 18650 cell internally (you typically can't remove it), they've used a $3 cell to create artificial price discrimination that isn't really justified by their cost basis.

Note here that capacities beyond about 3.5Ah require two cells. E.g. this light uses two cells internally to achieve the stated 6.4Ah capacity:

https://www.giant-bicycles.com/us/recon-hl-1800

Some cells such as this: https://lygte-info.dk/review/batteries2012/UltraFire%20BRC18650%204000%20mAh%20(Brown-Gold)%20UK.html claim 4000mAh capacity, but claims from 'brands' such as UltraFire are nearly always fraudulent.

  • battery spares - lots of bike lights sell 'battery packs', which are just an 18650 cell wrapped up in some plastic and metal. If you want to cycle at full brightness all night, then you will consider the cost of these. Alternatively here you can find a light that uses 18650 cells, either a cheap flashlight (but see beam shape below), or a bike light such as this one https://www.fenixlighting.com/product/fenix-bc30-v2-bike-light/ with removable cells. If you are going to be on the road at night then probably you will want to have a spare light as well. A small 'be seen' type might suffice here, or a helmet light that could be switched to the bars, or whatever.

  • light brightness - this is governed firstly by Stevens' power law. This states that perceived brightness for steady lights grows with the square root of lumens: https://en.wikipedia.org/wiki/Stevens%27s_power_law. So you need four times as many lumens (which means four times the power draw) to get something that appears twice as bright. Hence 100 and 200 lumens both be being described as for 'being seen' - 400 lumens would be perceived twice as bright as 100 lumens. More lumens is therefore 'expensive' in that it consumes more battery (400 lumens is 4x more power than 100 lumens), which means your light runs down quicker. However brighter lights often have a bigger battery, and for example the HL1100 light has 1100 lumen and 500 lumen settings, so you could use it as a HL500 but get the benefit of the bigger battery.

  • beam pattern. In Germany lights are regulated by StVZO which cut off the beam on the sides so as not to blind oncoming traffic. http://www.light-test.info/en/faq-en/169-stvzo-bike-lamps-regulations German market lights are marketed not with lumens, but lux, which is lumens per metre. Something like this '150 lux' https://www.bumm.de/en/products/akku-scheinwerfer/parent/196/produkt/196l.html? is about as bright as they go in Germany, and is equivalent to around 800 lumens.

Here if we use a flashlight like the one I linked above, the cost to produce that many lumens is only around $15, plus $5 for the 18650 cell, and maybe $10 for a quality mount. However flashlights are not shaped at all for bicycle use, so to be suitable for use in traffic, you'd be best to modify the beam pattern by using tape.

  • Durability/weather sealing/cooling - as mentioned you can get up to about 1200 lumens (single cell lights from Chinese dropshippers on ebay etc. claiming 4000 lumens are lying) from a single cell. However the more lumens you produce = the more power = the more heat to dissipate, so a light intended for continuous use on a bike for two hours at 1000 lumens or so might have heat dissipating properties, whereas a 100 lumen light would produce only 1/10 of the heat, so is cheaper to build. In addition, things like switches, etc. are subject to water ingress from rain, and a bike light could be more durable than a cheap flashlight for its intended purpose.

I'd not buy a light from Giant just because I don't see that they have anything special to offer, and bike lights are completely interchangeable. I'm sure their lights are perfectly fine, and if they are priced competitively with a good light from another manufacturer, then fine. But just because you own a Giant bike doesn't mean you need their light.

The 'Qoo10' light you link to has nothing to do with Giant. It's a generic Chinese light which they have spammed 'giant' onto the title. It's probably poor quality. Stick to lights with reputable reviews, preferably not Amazon reviews, which are often paid-for and unreliable.

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