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  1. #1
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    New question here. Rear Disk Caliper Location on a Disk CX bike?

    This may not be the best place for this, but here goes... Mods, feel free to move it...

    While researching disk CX bike frames, I see both seat stay and chain stay caliper mounting options. Reading the pro's and con's, there seems to be no real reason to choose one over the other. I've been comparing the Gunnar Hyper-X and the Milwaukee Bike Co Disk CX...

    Anyone have any opinions on the subject?

    Gunnar Cycles USA ? Hyper-X Disc Cross hand-built bicycle frames

    Milwaukee CX Frame Builder - OX Platinum - Disc - In Stock! : Milwaukee Bicycle Co. Ben's Cycle

  2. #2
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    The disc mount location is totally irrelevant to how the bike will ride or function, but if you are deadlocked on the decision and prefer one look over another, it's a legit tiebreaker.

    -Walt
    Waltworks Custom Bicycles
    Park City, UT USA
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  3. #3
    DWF
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    Besides giving subpar performance and a source of brake squeal, a disc brake mount on the seat stay that is not braced to the CS or integral to the dropout design itself is guaranteed to break said seat stay at the terminus of the disc mount under hard use.
    A man must have enemies and places he is not welcome. In the end we are not only defined by our friends but those against us.

  4. #4
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    Hey;

    There have been some reports here of snow building up on and icing the caliper on a low mount arrangement. This was on a Fatbike. I don't know to what extent a X bike will approximate that situation, but it might be worth considering. I do know from experience that the cool looks of a low mount are somewhat tainted by the increased difficulty of servicing the caliper, but not so much that I would abandon them. However, if it were a race bike that would see regular slimy service, I might think twice about a low mount just for the sake of serviceability.
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  5. #5
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    Quote Originally Posted by DWF View Post
    .....a disc brake mount on the seat stay that is not braced to the CS or integral to the dropout design itself is guaranteed to break said seat stay at the terminus of the disc mount under hard use.
    I've heard this before but is it really that black and white? Defintion of "hard use" in this case seems very subjective. I'm just looking for enlightenment on this subject. I have a custom frame with a rear ss disc without a brace, use the bike only as a general about town and road exercise bike, very litte if any hard use(no drops, jumps, occasional fire roads), so.......a concern or no?

    thanks, Brian

  6. #6
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    I'd say that your chosen brake cable routing will determine low- vs. high-mount (brake cable on the down tube vs. along the top tube), and then bracing if needed.

  7. #7
    DWF
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    Quote Originally Posted by calstar View Post
    I've heard this before but is it really that black and white? Defintion of "hard use" in this case seems very subjective. I'm just looking for enlightenment on this subject. I have a custom frame with a rear ss disc without a brace, use the bike only as a general about town and road exercise bike, very litte if any hard use(no drops, jumps, occasional fire roads), so.......a concern or no?

    thanks, Brian
    Yes, it really is that black & white. You could put caveats on it and say it only applies to frames using conventional seat stays or that or this or that or whatever, but it all comes down to the only thing resisting all the force of rear braking that is passing through that huge stress riser / can opener on the top of the mount is that spindly little seat stay. Builders learned this the hard way in the late 90's with disc's popularity explosion and unfortunately a few still learn it that way today.

    Same with forks. You stick a disc brake tab on a front fork that is not designed for the load that a disc brake brings with it and the same problem crops up: buckled fork blades.

    Keep in mind that frame failures are not just learning opportunities or inconveniences, they're potentially life threatening/altering to the rider.
    A man must have enemies and places he is not welcome. In the end we are not only defined by our friends but those against us.

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    I vote for normal mounting (not cs) only because it protects the (sometimes hot enough to melt spandex) rotor. CS mounted ones leaves the back part exposed and before I get flamed on this think about it, if you can get a rear QR to the back during a shoulder carry you could for sure get a hot rotor to the same spot.

  9. #9
    Framebuilder
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    Quote Originally Posted by DWF View Post

    Same with forks. You stick a disc brake tab on a front fork that is not designed for the load that a disc brake brings with it and the same problem crops up: buckled fork blades.

    Keep in mind that frame failures are not just learning opportunities or inconveniences, they're potentially life threatening/altering to the rider.
    Yup, there was recall just this week for forks that buckled due to poor disc design.

  10. #10
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    Thanks for pointing this out D. I did not bother to look at the Milwaukee frame link and didn't realize they were not bracing the seatstay. That's going to come back to bite them in the butt...

    -Walt
    Waltworks Custom Bicycles
    Park City, UT USA
    www.waltworks.com
    waltworks.blogspot.com

  11. #11
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    Re: Rear Disk Caliper Location on a Disk CX bike?

    Quote Originally Posted by Walt View Post
    Thanks for pointing this out D. I did not bother to look at the Milwaukee frame link and didn't realize they were not bracing the seatstay. That's going to come back to bite them in the butt...

    -Walt
    So, you're suggesting to not consider the Milwaukee?

  12. #12
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    Rear Disk Caliper Location on a Disk CX bike?

    Get the Gunnar, especially if it's the pink one. That's awesome!

    I'm pretty surprised the Milwaukee is lacking a brace. I've seen a frame snap in two right before my eyes. It didn't have a brace and it snapped right above the caliper mount. It was an AL frame in the early 2000's.

  13. #13
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    Re: Rear Disk Caliper Location on a Disk CX bike?

    Quote Originally Posted by Meriwether View Post
    Get the Gunnar, especially if it's the pink one. That's awesome!

    I'm pretty surprised the Milwaukee is lacking a brace. I've seen a frame snap in two right before my eyes. It didn't have a brace and it snapped right above the caliper mount. It was an AL frame in the early 2000's.
    The funny thing is that the Milwaukee and the Gunnar are bother made at the Waterford shop... You'd think they'd know better, maybe refuse to build them if it were truely an issue...

  14. #14
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    Quote Originally Posted by classrc View Post
    The funny thing is that the Milwaukee and the Gunnar are bother made at the Waterford shop... You'd think they'd know better, maybe refuse to build them if it were truely an issue...
    one would think...(just because someone does it doesn't mean it's a good idea)

    If it were me, i'd get neither frame. For the Gunnar I'd HATE to have downtube mounted cables on a cross bike that i'd be racing. Not just grabbing the downtube while dismounting but mud and ice stick and freeze onto the downtube cables and the zip-ties can/will snap. It's just better to have top-mounted cables if you're going to be racing. So maybe look elsewhere (or go for a custom frame) instead of a frame that will eventually brake or one that'll annoy you if you're racing it.

  15. #15
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    Gunnar's SS rear drop's are pretty snazzy, wonder if they would sell them without a frame attached to them?

    To pile on the Milwaukee disc mount hate, it looks like you couldn't possibly choose a worse spot for the vent hole. It's 180 from the top of the brake mount, exactly where unbraced mounts shear.

    I'm a CS mount fan, I won't call them "cons" but there are some things to consider.

    When using a cable disc caliper you are stuck with routing the cable via DT/CS. Unless you are willing to accept really odd runs of cable to the caliper off of the SS. The real drawback to the DT/CC routing is if using full length housing the lowest point is midspan at the BB. Ideally, to keep crud and water out, the lowest point should be at the end of the housing. In practice I have two bikes set up that way, ridden mostly in poor conditions and have not had any real issues.

    I've brought up before that the caliper mounted horizontally seems to collect mud/show/slush easier than a caliper mounted 45ish deg. Again in practice it didn't create a performance difference in my experience. But the chances a caliper loaded with crud having issues is greater than one that is clean. The housing running on the top of the CS to the DT can be a crud collector also. But our mud around here is physics bending clay that doesn't care how much mud clearance you have so that might be splitting hairs.

    What's the intended use? Fender's and racks for commuting? No waterbottle boss-skinsuit wearing-carbon tubbies-hose left running in dirt to make it more Belgiumey-local world championships?
    Slowly slipping to retrogrouchyness

  16. #16
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    No Way.
    Waterford should know better at least.
    - Garro.
    steve garro el jefe/el solo. coconino cycles www.coconinocycles.com www.coconinocycles.blogspot.com

  17. #17
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    Is it so bad?

    I have looked at the Milwaukee frame and see that it has a one piece rear ISO dropout similar to Paragon's DR2010. The Seat stay is slotted to the axle end of the D/Out and the upper tab welded to the stay. It seems to be already quite meaty off the the lower connection and should be able to contain loads within itself with this design.

    I would move the vent hole to a lower position however, where there is a neutral zone.

    Why not ask Waterford for there thoughts?

    Eric
    If I don't make an attempt, how will I know if it will work?

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