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

[incepi]

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!

I am aware of the Shimano recommended bolt lengths(and special Shimano bolts with safety features). I wonder if those requirements will last.

I remember when Shimano introduced disc calipers for mountain bikes in the late 1990s. The bolts had holes for safety wires, along with an elaborate installation procedure that described how to twist the safety wires. That process was ignored by mechanics, and eventually abandoned by Shimano. I expect the same thing will happen with the Flat Mount special bolts.

Common sense has a way of asserting itself over the advice of corporate lawyers.

Spacers could be used to meet the minimum 10mm thickness required for the shortest specified Shimano bolt.

It seems that SRAM is not requiring special bolts of specified lengths for their flat mount calipers.

[incepi]

Here's a little sneaky peaky of the Flat Mount fixture in development.

Flat Mount assembly.jpg

[Gattonero]

Park Tools already has a Flat Mount facing tool.

Disc Brake Mount Facing Set | Park Tool

Yes, just needs more cash

[Broady]

Somewhat related to this whole flat mount thing, I know that no one offers a post mount to flat mount adaptor. Is there a specific reason for this? I'm a machinist by trade so would happily make one if it were possible. Without having the flat caliper and post mount forks in front of me it's hard to see if it would be a clearance issue making it impossible.

Seeing this new Dura Ace stuff and the inevitability of a DA Di2 hydro shifter / DA flat mount caliper combo it would be interesting to know if you could run the new stuff on post mount forks albeit with a bit of tinkering.

[mmoore]

Somewhat related to this whole flat mount thing, I know that no one offers a post mount to flat mount adaptor. Is there a specific reason for this? I'm a machinist by trade so would happily make one if it were possible. Without having the flat caliper and post mount forks in front of me it's hard to see if it would be a clearance issue making it impossible.

from a very high level, I don't think you can physically adapt a frame with post mounts to accept a flat mount caliper, if that's the adapter you are trying to make. i haven't exactly looked at the geometry myself but i had inquired about that in an earlier thread and some mentioned it was not possible. the flat mount is very close to the axle and the angle is just that, parallel to the stay its mounted on. the post mount is quite a bit further from the axle and at an angle.

[incepi]

Somewhat related to this whole flat mount thing, I know that no one offers a post mount to flat mount adaptor. Is there a specific reason for this? I'm a machinist by trade so would happily make one if it were possible. Without having the flat caliper and post mount forks in front of me it's hard to see if it would be a clearance issue making it impossible.

Seeing this new Dura Ace stuff and the inevitability of a DA Di2 hydro shifter / DA flat mount caliper combo it would be interesting to know if you could run the new stuff on post mount forks albeit with a bit of tinkering.

It's not possible if you want the Flat Mount caliper to sit close to the frame or fork the way it was intended. You can make an adapter, but it will position the caliper well above the post mounting holes. This will result in an unattractive look and an undesirable performance.

[Broady]

Ah fair enough, makes sense.

[steve garro]

Please stop spamming my inbox with sales requests.

Thank You

- Garro.

[incepi]

Please stop spamming my inbox with sales requests.

Thank You

- Garro.

I have directly contacted hundreds of framebuilders around the world regarding my Kickstarter campaign for a Flat Mount fixture. So far you are the only person to ask me not to contact you. That is your choice and I respect that.

Why you have chosen to do so publicly instead of simply responding to my email is for you to explain.

I am responding here because you have chosen to bring this to the attention of the forum. You have stated that I have spammed your inbox. This could easily be misconstrued to mean I sent an email to your VelocipedeSalon inbox. I have not and I would not do that. Please do not misrepresent my actions.

I have posted a classified ad with Too Tall's knowledge and permission regarding the Kickstarter campaign.

[Too Tall]

Eric, calm down and do not invoke my name as a tacit endorsement.

[steve garro]

Why you have chosen to do so publicly instead of simply responding to my email is for you to explain.

As you have chosen this venue as your personal sales vehicle I feel it is totally appropriate to respond in a like manner.

- Garro.

[David Tollefson]

I have directly contacted hundreds of framebuilders around the world regarding my Kickstarter campaign for a Flat Mount fixture. So far you are the only person to ask me not to contact you.

You could also interpret their silence as a "don't bother me" stance.