The Brutal Engineering Rock Bottom Chain Tensioner is designed for those we cannot convince they do more harm than good.
It is virtually impossible to drop a chain with a Rock Bottom upper guide and chain catch setup correctly with a well maintained, properly tensioned, drive train.
Chain tensioners are a source of friction and in our testing even brand new tensioners setup perfectly use a minimum of 2.5% of your energy.
Chain tensioners hang out on the bottom of the bike were mud, grit, debris, and obstacles lurk.
If a tensioner bearing seizes at best your ride gets a lot harder. At worst you can’t pedal at all.
They require tools to remove your chain so if something happens in a race you’re out of contention.
If you have to bypass it your chain will likely be too slack and you must remove links.
We highly recommend using our chain catch over a chain tensioner.
Still not convinced? Well neither was our downhill team so that’s why we offer it.
We have designed our tensioner to be as reliable and maintainable as possible. The chain stays fully captured while one bolt removal allows full access for maintenance and replacement.
We created labyrinth caps to keep debris out of the bearing as much as possible. The rotation of the idler works with the grooved path to push dirt out.
The idler assembly is adjustable by rotating the tensioner upward to dial in the tension you want without needing to rotate the Rock Bottom frame.
It is designed to be very tough but flexible so if it gets hit it will bend before breaking. However plenty of obstacles can reach up and strike the tensioner so it is designed to be easily replaceable.
If the bearing seizes the cover can be removed easily. The tensioner mount can be left in place with no idler and you can ride back to camp without a drag.
Should the tensioner seize the idler is fairly slick in kinetic friction and lasts many miles before wearing out due to rubbing. The tensioner cover can be removed easily from the outside of the bike. The tensioner mount can be left in place with no idler and you can ride back to camp without a drag.
Includes all mounting hardware.