I've had these for 3 years and they are still going strong.I'll give you an image, a mental image of a ring of fire as your wheel turns at 15mph. It stays put on the spokes. Place them at equal angles of a circle to keep cycle balanced.The product works. One battery as very weak compared to the other.so i will have to buy batteries now. Bells bike shop sent the product as snail mail i guess. It showed up 27 days later. In the mean time my daughter didnt get this on her birthday. Will not buy from them again.I live in a place where vehicle vs bicycle accidents happen everyday and I wanted more light to help make me visible. I needed them twice the first night I got them. They're very easy to install and you just twist them to activate and deactivate. They're highly visible and I enjoy people's reactions when I ride by. Kids especially love them. I would ride through a little neighborhood every night and the kids would start shouting and laughing as I went by. I was going to buy a pair in red to really trick out my bike, but then I trashed my bike in an accident (bad pavement, no vehicle). But as soon as i get a new bike, I'm going to put more of these on it. Absolutely worth it.These lights do not put out much light. It has to be pretty dark to see them. I guess they might help cars see you from the side. I keep them on my bike all the time, but I usually forget to turn them on at night. I like that you can turn them off and on. Other wheel lights force you to remove the batteries to turn them off.. They use an odd size CR 927 battery that you are unlikely to have lying around the house.I used them at Burning Man. They worked fine; but they become difficult to operate after a few days in the dust. Two problems: 1) They become hard to turn on / off. You must rotate the colored plastic on its base to do so, and after they get dusty, they become hard to turn. 2) They become hard to remove from the bike spokes (assuming you want to remove them after the burn) with all the dust, too.They won't last an entire (8-day) 'burn; you'll want to replace the batteries in day 5 or so because they're starting to dim. Replacement batteries are hard-to-find and slightly expensive. I found them at in loose quantities at Batteries and Bulbs, but I wish I'd have planned in advance & ordered from someplace online more cheaply.So, they're ok for the burn, but I'm switching to el-wire.However, I'm going to try some new, non-dusty ones out for my city bike.the whole twisting to turn on is kind of annoying. it's round and slippery a square or hexagonal shape would be much easier to us. plus the light really only shows threw on one side. the clip to the spoke is awesome and works perfectly. why can't someone design a light that is super bright, motion activated and clips to the spoke instead of those other options that screw onto the tube nozzle? (I got those too. they're light functionality is awesome, but the nozzle connector is cheap plastic that you're lucky if you can get to stay on your wheel for more then a few blocks)I used these on my wheels with bladed spokes and on my wheels with round spokes. The clamp is not really tight so you have to really be careful it is mounted securely. They are fairly bright. I would use four on each wheel with two different colors facing opposite directions.I ride to work almost everyday, and now that the weather is dark and miserable, I wanted something extra to be noticed on the roads of London.I already have two front 'white' lights, plus two rear lights. I also have one on my back-pack, plus a hi-via jacket. All of these are fine, when traffic approaches you from the front or rear, but noting really shines to the sides - hence why I bought these.Once you're moving these do offer a ring of light on both wheels. In my case I bought one pair which face my right side (being a UK road rider), but if you will need to buy two sets if you want to visible from both sides (or just stick one pair on one wheel).These won't stop some idiot from cutting you up on the road, but I'm doing everything I can to be seen.Would recommend these.Both batteries completely dead on purchase. I can't contact Amazon and request replacement, instead I have to get to a post office and send the whole product back, so not worth the hassle. Purchased new batteries and the light's weren't particularly bright either. Wouldn't recommend this productUnable to try them need to get batteries ,not one of them works.They did come quick.Fácil y rápido de instalar, lo único es que tal vez esta muy pequeño. Oajalá fuera más grande para que fuera suficiente sólo 1 por llanta, pero tal vez quedaría mejor poner 2 en cada llantaWork fine but the clasp is incredibly difficult to wrap around spoke. The light is one sided and the lack of a intermittent flashing is a poor decision.