I got fed up of swapping my Cateye TL-LD1100 between bikes as I only had one bracket. For the price of a new seatpost bracket it wasn't much more to buy another new light. I'd seen the Alpkit Tau rear lights available so thought I'd give one a go.
Tau Rear Light (image from Alpkit website)
Construction and Mounting
The light unit seems very well put together. No creaking or flexing when pressure is applied. You certainly feel like it could be dropped from a great height and survive.
It's smaller width is good, as the large width is my only complaint about my Cateye light; sometimes my thigh nudges it or presses the button depending on where it's mounted on my seatpost. The Tau has no such problems, tucking in nicely underneath the saddle. It is very unobtrusive.
The soft rubber back is grippy, reducing the risk of the light bouncing around meaning a lighter elastic band weight can be used. The rubber bands go on easily enough with their big pull tags. The quality of the rubber will be the determining factor in how long this light lasts I think. I'm tempted to take a needle file to the points on the side clips that the rubber band engages with to prevent any sharp edges from fretting the rubber bands.
Charging is achieved via a Micro USB port hidden behind a rubber flap. This seems to engage OK and would be held in place and partly shielded by the bike frame or seatpost it is mounted to so I'm not too concerned about water ingress. I'd take it off the bike if I was washing it but I'd do that for any of my lights.
As the owner of a Koala seat pack, I would have preferred a method of mounting the Tau to a webbing strap, maybe a clip or some slots in the body of the light, to enable easy mounting to bike packing luggage. The small elastic band doesn't seem to hold the light steadily on a strap and I worry a bit about it falling off.is a bit small for it. More thought required, perhaps there is a way and I just haven't come across it yet. In the meantime I'll keep the Tau mounted to my seat stay, even though the angle isn't perfect.
I think its a good job it is so light given that the length of the charging cable supplied means that it invariably dangles in mid air from whatever charging port you are using on your PC or adaptor. However, Micro USB adaptors are now the standard for charging phones so everyone is bound to have a lead already plugged into a charger lying spare.
Light Output and Modes
Performance of the Chip On Board (COB) LED module is good with very little observable change in brightness over a 90º arc. One complaint I have with some rear lights is the focusing of the beam with a lens results in a high peak brightness but out of angle it isn't so good. The Tau overcomes this well. The spread of light is such that I can easily check that the light is still on just with a brief glance down at where it is mounted. No more holding my hand in front of the light to see the reflected glow! I think this would be an excellent light for urban commutes with traffic coming from all angles being able to see you.
Brightness is OK on low but on high it is really very bright. The stated 3 hour runtime in this mode would put me off using it unless conditions were bad or traffic particularly heavy. The "pulse flashing" mode is more of a steady throb and doesn't immediately catch the eye. Unlike the 6Hz flashing mode which is really eye catching and is my preference for the road. Especially good considering the quoted 18 hour runtime - that's enough for a couple of weeks of commuting and a long ride.
It has a micro USB, charges from my phone charger in hardly any time at all (note I haven't timed it). That's it!
Out and About
As mentioned above it is very bright and with a good arc of light and seems to last a long time which will be good as the Li-Ion battery capacity decays with time as they always do. I've recommended the Tau to a couple friends looking for bike lights.
Brightness, viewing angle and build quality are good.
At £12 including postage I think it represents a very good value rear bike light.
I bought a couple of the front lights which are excellent as "see me!" lights and have now fitted a front and a rear to all the bikes in the fleet.