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Probably a stupid brake question....

1213 Views 15 Replies 7 Participants Last post by  oicdn
On forks designed for 8 inch rotors, will a caliper for a 6inch rotor work as long as there is an 8 inch disc?

Reason being, my Julie came with an 180 disc, but the disc is short of the caliper, so would a new 8in disc solve the issue? It's a circle, and the mounts are IS, it's only moved higher up the fork so it's 8in specific right? It's a circle with IS mounts, so figuratively speaking, it SHOULD work right?

A little help...prolly over thinkin again...LOL. But this'll DEFINITLY suck if I need to buy a new front brake, LOL.
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erm...you can use any size rotor with any caliper, is that what you are asking? As long as the rotor goes in the right place (be it by adaptors on the caliper or whatnot) you are fine.
Well...cause I mounted the disc, and when I put on the wheel, the disc was short of the pads.

So I'm HOPING that Magura doesn't have an 8inch caliper for thier 8 inch systems, like Hope does. Only a specific caliper number will work for a specific size. My Magura Julie 180 isn't like that is it?

So I went and 2-day shipped an 8 inch rotor. I'm just hoping that it works cause I don't have a 8-inch caliper mount adaptor. The fork is designed for only an 8 in rotor. Will the 180 caliper work on the 8in ONLY mounts?

Kinda hard to explain....Kinda like teh Avid calipers/disc. You can't put an Avid 8-inch caliper on a 6 inch disc on IS mounts. The caliper mounts are DESIGNED for only an 8inch disc. So the Magura Julie caliper isn't 180mm ONLY is it?

Dude what in the flying fuck are you talking about. Seriously. I can hardly read what you type. Second of all, "Kinda like teh Avid calipers/disc" ....

There is only ONE caliper for avid mechanical brakes (well, one for MTB one for road). Like I said in my last post, you use adaptors to fit different size rotors. Use some common sense man.
See what Hope brakes do to you..LOL. I've only owned Hope brakes. Hope brakes don't use adaptors. They use different calipers. So when I switched from my boxxer to my JrT, I kept the same disc, but needed new calipers cause of the mounting on the boxxer. And same with my rear disc, when I switched to an 8 inch disc on my rear from a 6 inch, I had to switch calipers, not get an adaptor...

Hope Mini's are the same way, if you want a larger disc, you have to buy another caliper from Hope.

So in this Magura Julie case, I only need to buy an adaptor? What adaptor will I need to get since the disc mount is already mounted in an 8inch caliper position? Or since it's an 8inch mount, all I need is an 8in disc since all Magura Calipers are the same?

Is that clearer now seeing where I came from with the whole Hope caliper thinking? LOL.
Because the caliper is already mounted in the proper spot for an 8" rotor (due to your fork's design), all you need is an 8" rotor.
Well, this sucks. I just called up Magura and they told me thier calipers ARE like Hope. Where the caliper with the 180 disc I got, will only work on a 180 disc. Here's what he said:

"Our brakes are designed from the IS mount designed for 6 inch rotors. So our 180 Julie Caliper needs no adaptor for going to a 180 rotor if upgrading from the standard 6 inch. It's spaced correctly from that IS mount to accomodate that size rotor. It's really stupid that bike companies do that, and make the mounts size specific, they should leave that up to the user and brake companies. It makes tranferring parts a potentially costly venture. Also the fact that we use the metric system, kinda makes other rotors have compatibility problems because we have 190-210mm rotors which aren't EXACTLY 8inches either.....I would just buy an 8 inch disc and see if it works. My guess is it won't since the calipers are specifically designed for that size, but it MAY fit."

That sucks...LOL.
shit man, a caliper on a fork designed for 8" works with an 8" rotor. A caliper on a fork designed for 6" with an 8" adapter works with an 8" rotor.

"if you want a larger disc, you have to buy another caliper from Hope"

Hope makes different caliper mount lengthes (part of the caliper) that are best to use, but they work on the exact same system as all the others.
You did not NEED to switch calipers when you got your Jr.T, i'm sure hope would recomend it (or any shop selling you it) but it is certainly not what most people in the world do - they use adaptors.

The hope calipers are all the exact same, just extended a little further from the mount holes.

If you fork is for 8" rotors, then 8" is the least you can run. All you need is a standerd caliper and an 8" rotor. If you wanted to run a 10" rotor (dont think there is one but theoretically speaking) you would need a a +1" adaptor and a 10" rotor, get it?
The adaptor just sticks the caliper a little further out. For a 2" rotor diameter increase, you need the caliper to stick 1" further out (diameter).
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the metric - imperial system is a WHOLE different story though, that might cause some promlems

180mm is just a tiny tad over 7", but as long as its a standerd caliper (which most are) on a 8" fork, an 8" rotor should work fine.
I think I understand what you're saying. Basically, the fork designer is retarded. If you've already purchased a brake from Magura with a 180mm rotor, you're going to have to get a different caliper designed for a 160mm rotor instead. That is of course, if I understood you correctly.
Actually I DID need to switch calipers from the boxxer to JrT...LOL, the caliper wasn't even touching the disc mounting tabs on the fork. The caliper they make for the boxxer is BOXXER ONLY, whereas thier #3 caliper is the IS standard caliper. Like that # 3caliper if for 185mm front brakes only, but on a Manitou fork, it fits the 205mm. The distance from the hub is different...which is what I was asking this whole time. You want to see the chart yourself, go here:


Yes, the hole calipers are all the same with the extension from the mount holes. Thats what I was wondering, if this 180mm rotor is extended from the mount holes farther than a regular caliper making 180 SPECIFIC (like the Hope calipers).

I get the whole adaptor thing, I always did. I was just wondering if this 180mm supposedly "180 specifc caliper" would work on a mount system placed for a standard caliper positioned for 8-inch mounting as the extensions might be too far out from the mount holes cause it's "180 specificly spaced" caliper...

If you see the chart for the Hope calipers I linked above, you'll understand what I'm talking about.....
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see what happens when you buy a boxxer... that'll teach you.

i didnt read- this is a just a jerk reply, i saw disk problems and boxxer in close proximity and laughed.
disc problems and rockshox go hand in hand.
LOL, tell me about it. That's why I got rid of it.

I guess I'll just eat the money etc I invested for that disc/front brake if it doesn't work...if it does (which it should, I hope) bonus.....I'm trading my unused front HS33 for a Magura Louise with a 165 rotor, and considering that it's a "standard" caliper or whatever, it being positioned in the 203mm spot, atleast I KNOW it'll work. None of this middle caliper stuff and it maybe not working....bah....
hope makes any size rotor. you want a 184.6mm rotor? they can make it. just another option for you. its cheaper than many other options too.

back to the more important topic- boxxers suck. just to clarify- boxxers suck.
Yeah...they suck....well, Rock Shox suck...
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