1. usb rechargeable
2. good clip so it could be attached to a back pack or back of a jercey.
3. good attachment so it could be mounted on the back of helmet.
4.hardware so it could be attached to the rear of a rack
5.good side illumination.
6. charging inlet on the side, top or bottom so i wont have to get it off the bike to charge because the charging is from the back where it attaches to the seat post or rear rack.

does such a thing exist? tell about your favorite tail light.

The Blackburn 2'Fer meets all but #6 . That's my only complaint about the otherwise excellent light. I have to remove it from the supplied rubber band, or my own homebrewed Velcro strap, to access the rear-mounted USB port.

Usually something that has a clip for a bag or a jersey will fall off when clipped onto either, from bumps in the road. Fortunately they usually come with a bracket that is secure, mounts to the bike, and is a quick release. Most LED tail lights need to be aimed level and straight back to get good power aimed at the cars. Another reason to not clip to a bag.
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This will do what you want. I have one almost the same, but this one has better beam spread

https://www.cygolite.com/product/hotshot-pro-80-usb/

^^^ Good Choice^^^

I like the Hotshot Micro too, but it has only strap on rubber band mounts.

I've been using the light and motion vis 180 rear light for well over a year. It is as bright as the cyrgolite hotshot 80 and has a better run time. But the L&M is 2x as expensive and works well really only on a seatpost; the cygolite is more flexible. As much as I like my L&M vis 180, I'd recommend the cygolite as well at this point.

Cygolite hotshot .... I have one and feel a whole lot safer now .... I commute in the pitch dark

I've used Cygolite Hotshots since December 2011 and have yet to lose one clipped to a pannier for commuting or jersey pocket for recreational rides. Side illumination is decent and the mini USB plug is on the bottom. The spare I got in December 2014 has better firmware which flashes a couple times when it's turned on or off with a low battery which makes it hard to run out.

They include seatpost and seatstay mounts and sell a rack mount. I have no idea about helmet mounting.

The old one is bright for night use at 30 lumens although I'd prefer more during the day.

The new pro 80 should be much better for daylight use.

USB Rechargable is a Thing many companies offer Now..

Planet Bike and cats eye are 2 of them they should hit all your numbers


red LEDs dont draw Much so a Flashlight battery lasts a Long time* .. so, No faves, I have not Bought any .
AA I can recharge them

or (my Ideal) Wired to the headlight then to the Hub Dynamo types are My preference
Schmidt and Busch And Muller

* 20 year old Vista light is still working (now on my snow/ice Bike...Here it rarely drops below zero..



But if You work in a cubicle at a computer obviously Its easy to recharge ..

Contact Cygolite and ask them to send you the clip on attachment. Don't ask me why they don't include that with the original light They sent mine free of charge.

7. Modes for using the light in group settings.
8. Can be used for daylight riding.



My current light that I'm liking alot is the Cygolite Hotshot Micro - https://www.cygolite.com/product/hotshot-micro-2w-usb/

This light has everything that you are asking for, except mounting on the helmet. Personally I don't have this desire, so I haven't pursued it. What I really like is that it's bright enough to use in the day light and it has modes for riding in a pack at night. Nothing worst than having to be stuck behind a bright fast flashing rear light at night!

Also there's little tiny hooks that stop the light from accidentally coming off if it is hung on the saddle bag. This was the problem with my previous one, a Planet Bike Superflash. I got tired of being surprised with a lost light when I stop.

Finally from my experience the Micro has alot better side view visibility than the Hotshot.