This thing has saved me and the paint on my chainstays many times. Inexpensive and easy to install-feel silly even using the word install, it's so easy. Admittedly, a hose clamp inside some plastic won't win any design awards, but it's secure and works well-and will never wear out.
Originally, I worried the hose clamp part would dig into the frame's paint, but it's actually held a few millimeters off the surface. Only downside is that there's no way for a clamp setup like this to work with some carbon fiber frames' bulged out seat tubes. Overall, highly recommend for mountain and 'cross bikes, both singles and doubles.
I had one of these on a mtn bike for years. It didn't prevent the chain from coming off the small chainwheel and squeezing between the chain watcher and the frame ... but made it impossible to get the chain back up on the cogs ... it prevents that very well! Took it off, threw it away.
Just built up my first 29er rigid, and did a 1x9 using a short cage X-7. 32t ring with a bash guard and the 3rd eye. 300 miles and 1 40 mile race and no dropped chain. Could not ask for better performance than that!
I have always been careful shifting down the the small ring on my triple, but every once in a while, it dumps when I'm on a long ride and get a bit tired. I always knew about the chain-watchers, but when I replaced my cables, my front derailleur would not behave, and it was just before a 200km solstice night ride up Big Sur. Not exactly where you want to be dropping a chain. Put this on, and halleluia! No more dropped chains, no more extra caution, why did I wait so long! And this is on a recumbent with rotor rings. No problem.
It's totally cheap insurance Like another reviewer said, if the chain should come off just rotate the crank forward and it will go back on. I bet Andy Schleck wishes he had one of these on the stage of the 2010 TDF where the chain came off during a shift.
This thing works soooo well and it is cheap, something that rarely exists in the world of cycling today. I use it on my cyclocross race bike and my commuter, its simple, light and works! Well worth $10
If you have round seat tube and compact chain rings, this is a must have item for the bike. Even the chain is off, just rotate the crank forward. chain will get back on without get your hand dirty.
