The U-brake –like the pictured Shimano Deore XT SLR U-brake BR-M733- was probably most famous as the rear brake of choice for most GT MTB frames during the 80’ies and early 90’ies. While there where some aftermarket brakes that fit on u-brake post mounts the natural choice of the best U-brake was still the top end offering from Shimano.
Most U-brakes came with a beefy brake booster because they could easily flex common frames of the time without one and thus loose brake power, something a good U-brake do not lack.
Another thing not missing from the U-brake is weight, it is quite a bit heavier than any cantilever brake.
So what is the point with the U-brake anyway?
Fill me in if I am wrong here but the U-brake like this nice black Deore XT one pictured here are more compact than cantilever brakes used to be in the 80’ies before low profile brakes became the standard. The more compact a rear brake was, the less it would hit the riders feet when pedalling.
There was also a theory IIRC that the bottom chainstays where stiffer so they where more suitable for brakes. A cantilever brake could not fit under the chainstays as it would hit the crankarms. But a U-brake could fit in that tight area and function well, that is, until it clogged up with mud (which it would do fast since it was mounted under the chainstay).
As you can see this Shimano Deore XT SLR U-brake have seen better days, cosmetically. Function wise it works just as well as it did back in the 80’ies. There is some rust on steel parts and a lot of scratches from wear and tear, but it is only a testament to how great these brakes are.
Only thing missing is one index bolt, it has been replaced with a traditional bolt but the rest of the original hardware is still here. Madison brake pads have some (I suspect) life left in them.
This rarity would look good on any vintage mountain bike which uses U brake, or why not custom make a rigid fork with U-brake mounts?
It is for sale as pictured for 25 euro. Sold!