Best alloy for CNC brake calipers - 6061 or 7075?

[chazzawoods]

I'm looking at getting some new brakes. And have narrowed it down to the kcnc c6 dual pivot at 217g, and the planet x single pivot calipes at 203g.
A difference of 14g to me is practically nothing, and at the same price, I would be tempted to buy the kcnc's for their dual pivot, as well as improvements over the old cb1.

The only thing which bothers me is the choice of alloy; the planet x brakes are 7075, while the kcnc brakes are 6061. Apparently 6061 has too much flex in the arms of the caliper and weakens the braking force.

I don't want to stretch to the kcnc c7's 7075 alloy at another £80 over the c6. Any experiences with both calipers? Any reason why I should not opt for any 6061 alloy calipers? Thanks all.

[prendrefeu]

Hey Look!
I searched for you "KCNC C7 vs. Planet X CNC"
and look what I found:

viewtopic.php?f=3&t=105931&hilit=kcnc+c7+vs.+planet+x

[chazzawoods]

Hey Look!
I searched for you "KCNC C7 vs. Planet X CNC"
and look what I found:

viewtopic.php?f=3&t=105931&hilit=kcnc+c7+vs.+planet+x" onclick="window.open(this.href);return false;

Thanks! I would not choose to use the standard brake pads because I've got some carbon rim swisssssssstops for my wheels, and from the review you quoted, it is clear that any change in pads is an improvement in power.

[chazzawoods]

Do you think the 'forged' single pivot calipers would flex as much as the CNC ones? They are 225g, still light, but only £80

[prendrefeu]

The Planet-X CNC ones don't flex.
The Planet-X forged are simply heavier.

KCNC C7's may have some flex, according to some.

[blantonator]

I've been riding the C7's for sometime now and they're OK. They have noticeable flex, even at my 130lbs. They were a bit scarey on some descents earlier this year equipped with ultegra pads. I recently put the planet x's on my race bike, although they seem to have less flex, I haven't had them out on the road, as I'm recovering from a broken collar bone. The dual pivot design is better, but I feel like KCNC just took too much material off the C7's. I'll report back in 2 weeks when I'm back on the bike.

[chazzawoods]

I've been riding the C7's for sometime now and they're OK. They have noticeable flex, even at my 130lbs. They were a bit scarey on some descents earlier this year equipped with ultegra pads. I recently put the planet x's on my race bike, although they seem to have less flex, I haven't had them out on the road, as I'm recovering from a broken collar bone. The dual pivot design is better, but I feel like KCNC just took too much material off the C7's. I'll report back in 2 weeks when I'm back on the bike.

Thanks for your info, and I hope your collarbone gets better soon. If that's what these kcnc brakes can do then best I avoid them! I'll play it safe and get the planet x ones. The colour I like is out of stock, which gives me more time to read more reviews, but when I finally buy some brakes, a detailed review will be on it's way.

[MarkMcM]

The only thing which bothers me is the choice of alloy; the planet x brakes are 7075, while the kcnc brakes are 6061. Apparently 6061 has too much flex in the arms of the caliper and weakens the braking force.

I don't want to stretch to the kcnc c7's 7075 alloy at another £80 over the c6. Any experiences with both calipers? Any reason why I should not opt for any 6061 alloy calipers? Thanks all.

While I'm sure there are differences in the performance between these two brakes, the alloy used has almost nothing to do with it. All alloys of aluminum have the almost exactly the same modulus of elasticity (modulus of elasticity is basically the measure of a material's stiffness). If you made two otherwise identical brakes, one out of 6061 and the other 7075, they would have the same flex/stiffness. Any differences in flex is due to the size/shape/distribution of metal, and not its alloy, so you should separate out the question of alloy from the question of flex/stiffness.

[madcow]

I agree with Mark, the differences in the brakes is not due to the series of alloy. Compare a C6 and C7 and there is some subtle difference but very little. I think the C6 uses 6061 simply because it's less expensive and that model is more oriented toward budget. The 6061 should be less likely to suffer from stress corrosion cracking.

I'd first look at the Far and Near. It's a bit more than the C6 but less than the C7 and is a better performer than both the C6 and Planet X.

[chazzawoods]

Thanks for your advice. I'd never actually thought of the far and near brakes as being one of my options, it was mainly things in the £100 ($160) range such as Sram force, planet x etc.

Do you know where I can find the far & near brakes for a good price? Just fairwheel bikes to note so far at $290. Cheers