Educate me on rear dropout options for thru axles- Mtbr.com
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  1. #1
    650b me
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    Educate me on rear dropout options for thru axles

    I've been on Paragon's site looking at these and I'm overwhelmed. If anyone is willing to outline the options and their applications, I'd really appreciate it. Maybe it could become a sticky thread. Walt? Anyone?

  2. #2
    650b me
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    To add context, I'm looking to design a frame that will accept a Boost 27.5 x 3.0" wheel/tire.

  3. #3
    Ipso Facto
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    Use polydrops if your frame will be geared only or if you are using an eccentric bb. Use sliders or rockers if you plan on a single speed option or if you want to make small changes to wheelbase/rear wheel position. All of these have thru axle inserts and IS or post mount disc tabs. Interface to stays can vary. i.e. flange or tab. I prefer DT Swiss thru axle that are also available from PMW that will match the inserts you choose. Good luck!

  4. #4
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    I second the DT swiss 12mm through axle. But not the Polydrop, I am not a big fan of the extra screws, bolts and bits. Syntace looks good but not as widely used and more bolts so more time to change tires. And more complexity.
    I prefer the sliding dropouts over the rockers, as they are simple, work well and don't need to be any more complicated.

    Boost is just how you space the rear end on the through axle dropouts, the brake mount is still in the same place in relation to the dropout.

  5. #5
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    I just picked up a couple pairs of MODULAR 142/12 DROPOUT IN STEEL-DT-SWISS-SPEC :: MTB DROPOUTS :: STEEL DROPOUTS :: DROPOUTS :: Nova Cycles Supply Inc. for a lower budget alternative. I haven't really heard any feedback on them, but welding them up should be really easy. I'll drop a review after I build out in a month or so if I don't bork it too badly.

    Would love to hear if anybody else has tried these.

  6. #6
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    Those Allotec modular dropouts are difficult to mount a disc brake tab on. I used them on my personal MTB because I wanted to try them out. If you try to mount the tab on the seat stays, the tab hangs too far off the back of the steel part. You can mount it to the chainstay, but you need to make a large upward bend in the seatstay to allow room for the caliper.Educate me on rear dropout options for thru axles-30836017565_bdd5deb2b6_z.jpg
    Even with this bend in the seatstay, I had to use a 180 rotor to be able to get the caliper far enough forward to fit under the stay.

  7. #7
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    Thanks! I hadn't done cad diagrams yet, so this is something I'll need to keep an eye on.

    Though I might just cheat and stick it on the seat-stay. Worried about the exposure in a crash though. Pretty gnarly terrain around here.

  8. #8
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    Off the top of my head:

    Paragon hooded (either Syntace or non-Syntace): Great if you want that old-school look, allows some flexibility with heel clearance/unusual stays. More work to miter (IMO), requires that you attach a disc tab somewhere, look a little goofy with tapered stays unless you turn down the hoods on a lathe (or just cut/file them). Nice strong hanger, simple, totally unkillable. Best for TIG but can be fillet brazed too.

    Paragon Polydrop: Modular, baby. No need to attach a brake tab, worry about rack or fender mounts, or stress about whether you're going QR or TA (you can easily swap). A bit complex looking but very simple in actual operation (I've never lost a bolt on mine and I built one of the first frames with them back when Mark was prototyping them). Heel clearance can be problematic, and you'll want tapered stays to match up with the tabs. Can look goofy on very large frames due to tab angles. Can be TIG welded or slotted/silver brazed.

    Paragon Rocker/Slider: Again a nice modular system, but with chain tensioning (or just rear wheel positioning) capability. I prefer the rockers because I don't like the cantilevered look of the sliders (and I've actually had a couple crack chainstays over the years for really big/abusive riders) but they are both fine, basically. Both can cause heel clearance problems because they're wide/long, both save you the trouble of fitting a disc tab. Rockers are superior for touring bikes or other setups where racks/panniers/fenders need to be mounted since they're available with those mounting points built in AND they keep the caliper out of the way of said mounting points. TIG or silver.

    Black Cat Swinger: I'm not sure if Todd still sells these but they used to be available for sale. I built myself a bike with them and had problems with the dropouts moving under load both while pedaling hard AND when braking hard (so the right side would move forward, the left side back) to the point where the wheel/tire would lock against the frame under hard braking. They essentially only use one bolt to hold the wheel in place (the second bolt serves as the pivot). Built in brake mount, hooded design that is TIG friendly, unique look. Probably tricky to fillet braze but Todd does it! It should be noted that lots of people ride these and seem to have good experiences with them, I may simply be a unique case.

    Nova/Kavik (they appear really similar anyway? Kavik might not still exist though) modular: Never used these. Not sure I see the point of using them unless you dislike the look of the polydrops. Looks like it would be a bit annoying to mount a disc tab on the seatstay due to the positioning of the aluminum bit (not enough steel portion extending down toward the axle?). Cheap!

    Old-school Paragon plate-style: No longer made. An integrated-brake-tab (ISO) plate dropout with 2x12mm holes for the axle. Braze on your own nut. SUPER simple, ultra cheap to make, easy to join with a variety of different techniques. The ones I used to use WAY back in the day (we're talking the days of 135x12 and 150x12, folks) were just machined from 1/4" plate and not even relieved. And they were great! However, they had no pockets for the hub shoulders and hence with modern hubs they'd be... odd.

    2-Souls X12 and EVO2 sliders: I used the X12 ones once, they are basically the same thing as the Paragon hooded but with a flat on the front/back which can make mitering the chainstays easier (opinions might vary on that). The sliders are pretty much like the Paragons too, but a cast/hooded design that probably hurt heel clearance a little bit (but you might prefer the look). Made in Germany, and expensive. I don't recall much about these but I don't think it was too hard/expensive to ship them across the Atlantic.

    Paragon Toggledrop: Never used 'em. Cost a freaking fortune, have like 13 separate parts?!? Can anyone shed any light on what you would use these for and why? Mark's a smart guy so he must have had a reason to make them but I can't for the life of me figure out what that reason was.

    That's all I got, for steel. Anyone know of any others?

    -Walt
    Last edited by Walt; 06-23-2017 at 10:08 AM.

  9. #9
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    Ahhh, thank you, Walt. Your knowledge is encyclopedic, but without your willingness to share, it wouldn't mean much. You provide a great service to the framebuilding community. Seriously.

    I've been leaning towards hooded dropouts for their simplicity and clean look, but looks can be deceiving as I would still have to locate the brake tab and I don't have a fixture to do that. Now I'm leaning towards Paragon rockers. Is it true that all of the modular systems accept different inserts so I can run whichever skewer I choose? I count six, yes six! 148x12 skewers offered by Paragon.

  10. #10
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    Not every modular system uses every possible axle standard, but mostly, yeah. The only one you can't use with the Rockers (AFAIK) is the Syntace.

    I should have noted, the whole point of the Syntace is to make it easy to align the rear end of the bike - it uses eccentric nuts to allow you to keep the wheel in plane/aligned even if you did a pretty bad job keeping the chainstays and seatstays the same lengths. Don't assume you can get away with *anything* - but if you usually end up filing your QR dropouts a little to get rear wheel alignment right (no shame in that, we've all done it at one point or another!) then you might consider the Syntace just to give yourself some wiggle room on alignment - you can't file a through axle dropout!

    With the rockers and sliders, you can at least tweak wheel position a little bit if needed (if you don't get the chainstays to match each other perfectly). Hence less/no need for the Syntace system. It would also be quite an operation to make the dropout if you wanted to combine them.

    I realized I forgot the Paragon Toggledrops. Editing...

    -Walt

  11. #11
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  12. #12
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    A couple on inputs on Walt's encyclopedic post:

    I think toggle drops are for belt drives.
    I don't think Paragon makes slider/rocker inserts for Maxle anymore

    The other thing I've been pondering is using Paragon flat mount dropouts. Reason being they're available in steel (vs. stainless) and plate style. I've done fillet to hood style before and, while one can make a sold joint this way, I just feel better with slotting and plates. Plus it's easier to do by hand. AFAIK, Shimano road and mountain calipers are cross compatible, so you'd need to get a flat mount caliper or use the adapter for flat mount to 74mm caliper. I assume SRAM is the same, but I could be wrong. But I can't think of a reason why it simply wouldn't work to use the "road" mounting on a mountain bike, right?

  13. #13
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    Thanks, Feldybikes. Those flat mount dropouts caught my attention for the same reasons you gave. But I have two reservations. One, I think they're kinda ugly, and two, the included angle (I believe there are two options) doesn't seem appropriate for mountain bike geometry.

    Peter, did you want to tell us a story about your picture?

  14. #14
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    Syntace drops rock for B+ builds !!
    Paragon sliders are also good as they offer a few different options , plate style or hooded and the inserts are interchangeable.
    Standard hooded PAragon drops as PVD pointed out above also work great!

    I would not recommend Toggle drops for the beginning builder , that's quite the undertaking to work with. Stick with the simple and proven stuff.
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  15. #15
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    Quote Originally Posted by golden boy View Post

    Peter, did you want to tell us a story about your picture?
    Not to speak for Peter but I had the same question when he posted it. However, now that I have the Paragon hooded dropouts in hand, I can see what he did there. I like it a lot. Clean, simple and light. I prefer to have the caliper inside the triangle.

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