Flat Mount tab

[incepi]

One of the issues with the new Flat Mount standard is the complexity of available caliper mount installations. You either have to notch or miter the chainstay, or use a dropout with an integrated caliper mount. The ISO and Post Mount systems used a simple tab that was cut to match the frame or fork profile, and simply welded in place. They were inexpensive, flexible, and straightforward.

I am experimenting with the idea of a Flat Mount tab, similar in concept to the ISO and Post Mount tabs, but positioned horizontally rather than vertically. The tab could then be cut to match the chainstay, just like an ISO or Post Mount tab. The issue is how to attach it to the chainstay if the placement zone is not perfectly parallel to the tab. It's not an insurmountable challenge. Rods or other simple pieces could be welded from below to fill the space under the tab, providing a level surface for the tab. Alternately, the tab could be fillet brazed in place.

Anyway, I thought some of you might be interested in an alternate method, even if it is just a starting point for developing other ideas.

DSC_0177.jpg

[EricKeller]

Eric, that's a cool idea. It seems like they designed the standard to require holes in the chainstay, have you tried your tab?

[incepi]

Eric, that's a cool idea. It seems like they designed the standard to require holes in the chainstay, have you tried your tab?

I have not tried it yet. I will this week.

You are probably right. Flat Mounts were likely designed to be integrated with the chain stay, to simplify molding of carbon fiber frames.

It is possible to avoid mitering or notching the chain stay if the chain stay is bent or angled to provide clearance for the bolt heads underneath the plate. With this plate, some applications might not need any manipulation of the chain stay if the angles are shallow enough.

You could also attach the plate to a raised base, and avoid any bending or notching, even on a road frame. The only potential issue is the location of the seat stay. The top of the caliper might touch the seat stay.

I will update the thread as the project progresses.

[shirk]

Check out what Rick Hunter has done.

https://www.instagram.com/p/BB-xyAtr...=condorcazador

https://www.instagram.com/p/BBbNPy0L...=condorcazador

https://www.instagram.com/p/BBbLd0FL...=condorcazador

[incepi]

There is no reason why a Flat Mount can't be installed on a seat stay, even though it was probably intended to be located on a chain stay. When ISO and Post Mount were introduced, the obvious placement locations were on the seat stays. Creative and resourceful framebuilders found ways to position them on chain stays. So why not do the same thing in reverse, and put flat mounts on seat stays? It actually does not look bad, and gives the framebuilder more options. If a reinforcement is needed between the seat stay and chain stay, so what? It's a well understood and accepted practice.

I don't know why Shimano did not design flat mount calipers to be more compact, like the original Hayes and Hope 22mm mount calipers. Those designs fit into some very restricted spaces frame nicely.

img_0745.jpg

[AllKnownBikes]

Be mindful of the special hardware required to mount the flat mount caliper to the stays. Shimano is offering 6 different bolt lengths, depending on the "chain stay thickness" mounting point, so make sure your plate matches one of these thicknesses AND you supply or at least can suggest which bolt is needed from Shimano to make use of the tab.

Good luck with the design!

[Gattonero]

Check out what Rick Hunter has done.

https://www.instagram.com/p/BB-xyAtr...=condorcazador

https://www.instagram.com/p/BBbNPy0L...=condorcazador

https://www.instagram.com/p/BBbLd0FL...=condorcazador

Then the workshop is relying heavily on you guys, unless we have to invest another £2-300 for a tool to face this new mounts.

[incepi]

Then the workshop is relying heavily on you guys, unless we have to invest another £2-300 for a tool to face this new mounts.

Park Tools already has a Flat Mount facing tool.

Disc Brake Mount Facing Set | Park Tool