I’ve mostly stuck with pretty integrated PMW flat mount dropouts in prior builds but the cost of those is pretty high and I’m trying to offer some more budget-conscious build options. I’d love to hear what y’alls favorite choices are for doing flat mount on the cheap-ish.
My only real requirements are:
Replaceable derailleur hanger
Compatible with 19mm CS & 13mm SS
Ideally stainless
It looks like the PMW snap ring with their individual caliper mounts might be the most economic discrete solution at $95 for dropout + hanger + caliper mounds (all stainless).
Allotec and Tange have some other integrated options at BFS but imo they’re pretty ugly and constrain the seat/chainstay angles/diameters.
The Lichen OGQ is super purdy, but on the heavy and expensive side.
I do like that some of the integrated dropout options remove the issue of SS/caliper interference, but I have a toob bender that can address that issue as well.
I’m putting my own research here, feel free to peruse.
We’re currently testing a 3D-printed FM160 “adapter”. It’s roughly $40-50. A FM140 adapter would be ~$5 cheaper. FM160 allows you to rotate the caliper to give more caliper-SS clearance. Not much cheaper than the other options, but much faster and more accurate IMO.
The fabrication of it was very easy but did require some care when setting everything in the sub assembly fixture. I welded the dropout, fm adapter, and chainstay all at once. I should have the frame back in a week or two and will report back on the results.
So technically you would be stepping on Long Shen’s toes
If you could get your hands on the inserts, I think there could be a low-cost design using a laser cut plate style dropout as demonstrated by @gschwell
@Daniel_Y good point! I’m much better friends with Kevin at Pine than the folks at Long Shen I’ll poke around the idea of doing a plate-style dropout. Would definitely be way cheaper than anything round/flanged.
A flat plate dropout is quick/cheap/easy for ISO mounts because it’s essentially two dimensional. I’ve had good luck with both SS and geared models. They end up costing $15-$20 for a set of dropouts. Granted, this is for my own bikes, not something I’m trying to sell.
I use the Paragon snap ring dropouts and their flat mount bosses and machine the stay for FM160. With my benchtop mill, it took a few tries to get a rigid enough setup to make the cuts with the 5/8" end mill. It works but it’s a pain in the ass.
But I think the best solution I’ve seen so far is PVD’s Sidewinder design. It mimics the old IS standard with proprietary adapters that can work with flat and post mount calipers. It’s a really flexible system. Plus, the mounting tab is shorter than FM160, which would save on printing costs.
Really I’d love a 3d printed UDH dropout on the DS with a Sidewinder dropout on the NDS. It’d work for gravel and mountain bikes. You could run 140-180mm rotors and both caliper styles. Then get Andrew at BFS to sell them along with the adapters so they’re available to everyone. That’s the dream.
I think I’m going to try the PMW 1-1/2" dropouts with the 5/8" inserts and see how that process feels. Seems like it shouldn’t be too rough, especially once I have a mill with legible indicators
I would guess those 3D-printed inserts cost ~$20-30 for the pair. However, with enough scale, those parts could easily be machined.
If we could get the aluminum flat-mount tab and steel dropout inserts machined, it would be a really cool plate-style architecture for flatmount.
I often find frame builders are at the mercy of the component suppliers. I am hoping that the bright minds of this forum can create our own designs and have them produced.
And to match the cool plate flat mount DOs, an x-mas themed UDH DO The whole plate should probably be stainless so the rotating hanger doesn’t mar the paint. This design requires an insert that could be 3d printed or machined but anyone with a lathe could knock it out pretty quickly.
I’ll poke around the idea of doing a plate-style dropout. Would definitely be way cheaper than anything round/flanged.
The whole plate should probably be stainless so the rotating hanger doesn’t mar the paint. This design requires an insert that could be 3d printed or machined but anyone with a lathe could knock it out pretty quickly.