[Wombat]

I have just put one on my bike and have a question about "truing the caliper" as the instructions call it.

They say to mount the calipers on the forks and then set the 1/3 2/3 gap for the pads while the CPS bolts are loose. Then you have to move the outside pad in until it hits the rotor and holds the actuating arm firmly. You then tighten the CPS bolts and back off the pads to get the correct spacing again.

I understand that this is meant to align caliper and pads with the rotor, but it seems that doing this pushes the caliper towards the outside so that the inner pad is now rubbing on the rotor and even using all the adjustment in both pads doesn't allow the pads to get back to a 1/3 2/3 spacing. To my limited understanding it seems that because the inner pad doesn't move you will always skew the caplier to one side.

I have the brakes working well (still breaking in), but I am obviously missing something when truing the caliper.

Advice would be appreciated.

Wombat

 

[shiggy]

I basically center the rotor in the caliper. The 1/3-2/3 thing is just a guide line and it is not the clearance between the pads and the rotor. It is the position in the caliper slot.

The rotor does flex toward the inner fixed pad. The caliper itself does not move. If it does you need to tighten the mounting bolts.
Adjust the inner pad is as close to the rotor as possible without rubbing. Then adjust the outer pad to get the feel you want. If you can see the rotor flexing toward the inner pad when you pull the lever the inner pad is not close enough to the rotor. Be sure to adjust for pad wear with the pad adjusting knobs, not the lever barrel adjuster.

 

[Wombat]

I basically center the rotor in the caliper. The 1/3-2/3 thing is just a guide line and it is not the clearance between the pads and the rotor. It is the position in the caliper slot.

The rotor does flex toward the inner fixed pad. The caliper itself does not move. If it does you need to tighten the mounting bolts.
Adjust the inner pad is as close to the rotor as possible without rubbing. Then adjust the outer pad to get the feel you want. If you can see the rotor flexing toward the inner pad when you pull the lever the inner pad is not close enough to the rotor. Be sure to adjust for pad wear with the pad adjusting knobs, not the lever barrel adjuster.

Thanks for the advice. I had the impression that the larger the gap to the inner pad, the more modulation you got. But as you suggest the 1/3-2/3 is just a guide and it is working well for me.

In 1/2 an hour taking this bike out for a ride along with my other bike with 200 mm XTs, a friend will ride the Avid-equipped one first and we'll swap around; it should be interesting to compare. The Avid has the 203 mm rotor on it as I found with the XT that that suited me best.

Wombat

 

[shiggy]

Thanks for the advice. I had the impression that the larger the gap to the inner pad, the more modulation you got. But as you suggest the 1/3-2/3 is just a guide and it is working well for me...
Wombat

You can adjust the modulation with the inner pad. You get the most power with my method and also are able to adjust to point in the lever pull the pad contacts the rotor.

If you have the inner pad too far from the rotor you start getting uneven pad wear and it can contribute to squeal.

 

[t4t3r]

any information on the comparison Wombat? after the trouble with my shimano deores, its not really worth the hassle since they dont really feel all that good anyway. i was thinking of getting a set of the avid mechs instead.

 

[Wombat]

Avid & old XTs compared

any information on the comparison Wombat? after the trouble with my shimano deores, its not really worth the hassle since they dont really feel all that good anyway. i was thinking of getting a set of the avid mechs instead.

I found the Avids had somewhat less modulation than the 4 pot XTs , they felt slightly more on/off, not a problem at all, but it seemed noticeable. As far as power goes, my friend is rabidly anti cable discs since he owned the almost useless Formulas a few years ago (and they were shocking; far worse than any v-brakes I've tried) and he felt the XTs were far stronger. I thought that the Avid's weren't quite as strong, but they are very new with less than 60 miles on them.

The feel of the cable brakes is also quite different as they don't seem as smooth as the hydraulics, and they don't have the wonderful sound that the XTs have (like a piece of grass caught in the rotor). I always regard it as a sign that all is right with the world.

I hope this helps; I think both are good, the feel is probably the biggest difference and I do prefer the XT, but this might change with a few more miles.

Wombat