Disc Brake Calipers, Rotors and Hose

From Pvdwiki
Revision as of 18:33, 29 November 2007 by Pvd (talk | contribs)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to: navigation, search

I got the new XT BL-M775 Servo Wave Hydraulic Disc Brake Levers on my bike.

Just testing the bike on my street, the brakes felt extremely powerful. The claim is that these levers increase brake power 20% and I don't think they are lying. I had 7" front and 6" rear rotors on the bike with the older levers. I was planning on going back to 8" front once the rains came and traction improved. With the improved power of these levers, I actually ended up going 6" front and 5" rear. This setup has produced the finest brake action that I have ever experienced on a bicycle.

The general rule of thumb with the new servo-wave levers is that you run a rotor size one size below what you were running before.

The biggest problem that I came across was that the new XT brakes have gone banjo-less at the caliper, so hose can now be cut from bulk. It's a good thing, but that means that I didn't have what I needed to connect a longer line for the rear brake and my older BR-M765 calipers. In getting caught off guard with this, I had to jump through some hurdles to get a longer rear brake line in. I didn't have a spare with a banjo, so I needed to fabricate one with some old jagwire parts. It seemed to have worked.

You do not need to use the new caliper to use the new levers. It's nicer to go to the new stuff, but the improvement is really in the levers.

I played a bit with the stroke adjust. I found that the smallest stroke was best for me. I have regular sized hands for a guy. A person with larger hands may find that a longer stroke works better.

The reach adjustment is great. Very easy to change, even while riding.

The entire lever is about 1/2" longer from the pertch than older versions. I had to move the shift and brake levers inboard a bit more than I already had. Luckily, I had just enough room before the bar bend to get my preferred lever position. I now have about a 1.125" gap in the bar from the end of my grab-on grip to the brake perch.

While the system was dry, the servo-wave feature felt wrong, like the lever was sticky at the start of action. I was worried that this would be a deal killer. Once the hydraulics were fully bled, this felling went away and the lever action is extremely smooth as I would expect from Shimano brakes.

The brakes work superbe on the trail. Perfect modulation.

With regard to weight. Since the rotor size shrinks with the new levers, the weight of the entire system is reduced far more than just the change in levers. This is also critical wheel weight.




A cheap sram 5" rotor over a 6" shimano for the rear.

The 5" rotor mounted in the system. Very light. Very tight.