I got this set up on MTBR, realized I needed to share this over hear as well.
Heres the review threads but BT21 is just barely starting, my review unit wont be here for a couple more days. But I have expanded my “testing setup” so will cover about anything people are interested in for information (except sphere test)
And standard GearBest free (or pay for faster) shipping options. World wide.
Due to gearbest system set up, it doesnt currently accept multiple coupon code use per order. So at this time, if you order 2 lights, it will have to be 2 separate orders. But if you want 2 of the same light, then it works perfectly. So say 2 BT40S kits, coupon will affect both kits not just one. But if you want a bt21 and a bt40S or one light head and one kit, you will need to do separate orders to use both codes.
If you go for “the lights without the battery” you will only have light head and that’s it you have to buy separate battery pack like this one, or this or this etc. or you can buy battery case like this one and use regular 18650 cells. Unfortunately it is hard to confirm quality of those and similar packs/used cells…
You will also have to buy appropriate charger for those battery packs…
This option is intended for those that already have (oftenly several) battery pack or made one.
If you don’t already have battery pack it is advisable to buy complete set.
the complete set actually comes with good batteries as well (not cheap chinese ones) BAK Cells. Which is why the price is higher than most for the kit. Get what you pay for or in this case, IMO, you get more than you pay for (which usually NEVER HAPPENS)
Actually like 70 cents cheaper on The group but yes I know. Better pricing requires heavy numbers due to nitefighter wholesale pricing. And the light head only from gearbest includes everything except the case,battery, and charger.
Tigris99 forgot to mention that the BT21 no longer comes with a GoPro mount (shown wrong in the pic) but comes with the standard o-ring mount. Both lighthead and kit come with an extension cable too (doubt Ebay link does).
Most of these cycling lights would be fairly easy to adapt to a 1/4"-20 tripod threaded connection. Couple Chinese GoPro style mount pieces and you're set. (Probably some slight modding needed to mount.)
Note Style 1 adapter won't thread into the light, so you may be better off with Vancbiker's mount below. I believe that 99.9% of lights use an M4 mount screw (threads the standard o-ring mount into the bottom of the light head).
let me just add some: