These aren´t good times for being an V-brake, I guess. Specially within an AM orientated group.

 

Don't go for the parallel push system! Almost every single incarnation of the XT ( and some XTR) parallel push v-brakes ended up squealing like a pig and developed a ton of play in the linkage. The parallel push system only achieved a marginal increase in feel and performance compared to the non parallel push brakes. They are not worth the trouble, not to mention some of the XT brakes just look hideously large.

 

Agreed, not worth it. Any benefit is an illusion, in my mind. Same with Avid's "arch" technology, which was at least quieter than Shimano's Parallel Push, but still unnecessarily complicated.

 

Thanks for the warnings. The bushings are worn on my Avids and the tension wires no longer stay fully bent; the resulting asymmetric pad wear is getting to be a hassle. Maybe some M530s or new Avids...

 

Asymetrical pad wear? You mean there´s one side contacting earlier with the rim, or grabbing stronger on it? That´s not solved with parallel push V´s anyway, if that was your aim. Try to set them to the smaller spring preload possible on the lever arms, that should make easier to get them to work symetrically. A high tension on the springs makes them dumb and not really sensitive to further adjustments.

 

The advantage of parallel push is it reduces the number of degrees of freedom needed for pad adjustment. After 20 odd years of adjusting cantilever brakes I wouldn't mind a more disc like mechanism. The problem with worn brake arms is there's differing amounts of friction in the pivots, which is fixed by any newer set of brakes. In the meantime, the resulting uneven load on the pads when they contact the rim causes asymmetric wear from a combination of differing pressures and changes in positioning of the rim as the pads wear. Reducing spring tension is not the solution. While adjustments are easier, lower tension is less able to compensate for pivot friction and related stuff like drag in old noodles (I've found this out the hard way). A better workaround is to fiddle with the brakes until you get the setup more or less right and then regularly switch the pads from one side of the brake to the other. I use cartridges, so swapping isn't much hassle, but I ride enough it's getting pretty old.

 

The late model parrallel push brakes also gained a lot of weight over the first ones back in 1996. With the people still using v-brakes tending to be weight weenies, having a heavier v-brake wasn't helping shimano's sales.

 

The advantage of parallel push is it reduces the number of degrees of freedom needed for pad adjustment. After 20 odd years of adjusting cantilever brakes I wouldn't mind a more disc like mechanism. The problem with worn brake arms is there's differing amounts of friction in the pivots, which is fixed by any newer set of brakes. In the meantime, the resulting uneven load on the pads when they contact the rim causes asymmetric wear from a combination of differing pressures and changes in positioning of the rim as the pads wear. Reducing spring tension is not the solution. While adjustments are easier, lower tension is less able to compensate for pivot friction and related stuff like drag in old noodles (I've found this out the hard way). A better workaround is to fiddle with the brakes until you get the setup more or less right and then regularly switch the pads from one side of the brake to the other. I use cartridges, so swapping isn't much hassle, but I ride enough it's getting pretty old.

Say what? No offense, twest, but it sounds like you've got some pretty fucked up pivots.

The left pad kinda needs the right pad to press back equally hard for any effective braking to occur, and vice-versa. If a gummy or rusty pivot on one side is preventing free movement of the brake arm, it just means the lever is going to take that much more of your hand strength to activate.

The only thing Parallel Push is "solving" is a chamfered or beveled pad face (relative to the flat pane in which it started life).

But this is never going to mean you're getting incomplete pad contact on the rim, because the pad is wearing due to contact with the rim. The pad face will always fully contact the rim, even if worn to an extreme angle.

But more to the point, with cartridge pads being as thin and unincumbered by excess material as they are, they don't have much of a chance to wear at a funky angle. They're toast before they can get a couple of degrees off.

The extra pivots just add up to a selling feature, adding expense, complication, and weight in the process. Throw a set of dirt simple Avid SD-5s on that bike and never look back.

 

Throw a set of dirt simple Avid SD-5s on that bike and never look back.

word.

also, if you are having major stiction issues with the pivot check the brake mounting post. remove the brake arm and lightly sand the post. sometimes you have to take a file to it but this has helped me countless times when working on customers bikes.

 

Say what? No offense, twest, but it sounds like you've got some pretty ****ed up pivots.

They're not all that bad. But after 10 years and around 15,000 hilly miles and a lot of rain, mud, and snow it's getting to be a hassle to get even motion out of the arms even with recently lubed bushings. Pivots are all aluminum, so no rust, but enough wear to reduce pad life by maybe a third if I don't rotate pads regularly and perhaps a fifth if I do. But I've bike commuted through not one but two rainfall record setting winters in Portland and Seattle and many other years as well so some of the other brake hardware is coming due.

If a gummy or rusty pivot on one side is preventing free movement of the brake arm, it just means the lever is going to take that much more of your hand strength to activate.

My experience is the sticky one usually just pulls the other arm over farther, screwing up the setup.

remove the brake arm and lightly sand the post. sometimes you have to take a file to it but this has helped me countless times when working on customers bikes.

Thanks, though I have more the opposite problem, I think. Or at least I'm pretty sure it would take a lot of sanding to get the grooves out of the bushings. At which point they wouldn't fit anymore.

The late model parrallel push brakes also gained a lot of weight over the first ones back in 1996. With the people still using v-brakes tending to be weight weenies, having a heavier v-brake wasn't helping shimano's sales.

I'd noticed that. In this case I'm not counting grams; I'd have gone disc if the fork mount wasn't obsolete and the rear triangle had mounts. But that's not the case, so rim brakes it is.