Adapter for Flat mount caliper on post mount frame

[JA-Q001]

So, wanting to upgrade to hydraulic brakes on my CAADX, I saw a good deal on some SRAM FORCE shifters and calipers for a great price.

 

My only problem was that my CAADX still takes a post mount caliper on the fork and these Force calipers are both flat mount.

 

I searched everywhere and NO ONE makes an adapter to make a flat mount caliper fit a Post mount bracket. Through my endless googling I found 1 guy that made his own bracket and this inspired me to make my own "problem solver".

 

So first up was to get what the shape and geometry of the caliper would need to be. I put the caliper so the it sits correctly on the rotor, clamped the brake lever and rotated the wheel ever so slightly until it looked like there was enough space around the post mount brackets to be able to create an adapter.

 

 

I took a nice side on pic so that I could work out what was needed from the pic. Then in Paint (I know) I draw in the basic shape. I researched the bolt spacing for both calipers and from this I had a blueprint.

 

 

Now, I only had basic tools to be used, so I found a piece of 5x12mm aluminium flat bar and worked from there. Clamped it in the vice and heated the bar up and the bent it. getting the final sharp inside bend I used a hammer . After getting the basic shape correct, I measured out the hole spacing and drilled those, taking great care with the flat mount spacing and countersink. and then a lot of filing and sanding to get the final shape.

 

 

After fitting the caliper was not aligned with the rotor,. I first tried bending in place, but soon found out that this is not a good idea. This meant that I repeatedly had to take off the adapter, bend it slightly in the vice and then refit to check, but I finally managed to get it lined up correctly.

 

 

Only thing that was still miscalculated was that I needed spacers underneath the adapter, on the post mount brackets, in order to lift the caliper enough so that the rotor does not make contact with the top of the caliper.

 

 

Was fun making this, but its strange that a company like problem solvers does not make an adapter like this, maybe its because of most frames being too different with the filling in between the post mount brackets. But still, I got it to work and its solid and does not affect braking in any way. Maybe I could get one machined on a later stage and get it anodized black, but for now this is 100%.

 

Now others with the same problem has an idea how to solve it.

 

[igg]

Not sure how safe that is but definitely worth submitting to gcn hack/bodge.

[Kalahari Vegmot]

Lekker man, love it!

[Schnavel]

Very nice work indeed!

 

I have a mate with the exact same problem - will forward him the link.

 

May be worth having a drawing made up and then getting a shop to make a proper bracket on the CNC. Know any friendly engineering shops?

[Ki11gar]

Thanks @Schnavel. I have indeed been looking at this exact problem. 

I am sure I found the same guy that you did. 

 

Very impressive, I think I will follow your lead! 

[JA-Q001]

I can make a basic cad drawing of it, then attach it to the thread, then if anyone knows of an engineering shop that will make it (cheapishly) they can just mention it here.

[splat]

These guys are selling them online:

 

https://www.assolutions.ca/shop/adapters/flat-mount-brake-caliper-to-140-post-mount-frame-fork-with-140-rotor/

 

 

Flat Mount Adapter Guide

https://www.assolutions.ca/flat-mount-caliper-to-post-mount-adapter-guide/

 

https://www.assolutions.ca/flat-mount-caliper-to-post-mount-adapter-guide/

[andreas17777]

Has anyone else made some adapters I can purchase? Just need one.

[Schnavel]

Thanks @Schnavel. I have indeed been looking at this exact problem. 

I am sure I found the same guy that you did. 

 

Very impressive, I think I will follow your lead! 

 

Ki11gar ended up making some - drop him a message.

[andreas17777]

Hi, i'm making the following adapter. If anyone needs one let me know. 

 

https://community.bikehub.co.za/topic/177590-adapter-for-flat-mount-caliper-on-post-mount-frame/

[magyar.viktor78@gmail.com]

I can make a basic cad drawing of it, then attach it to the thread, then if anyone knows of an engineering shop that will make it (cheapishly) they can just mention it here.

Hi, I read your impressive solution, congrats. Do you have made the CAD Version, can you send it?

[splat]

Some for sale here:

Edit: Not mine

https://bikehub.co.za/classifieds/item/mountain-bike-brakes/1641/flat-mount-brake-to-post-mount-frame

 

Edited August 5, 2022 by splat

[JA-Q001]

Hi, I read your impressive solution, congrats. Do you have made the CAD Version, can you send it?

 

Was a while ago, Ill have to look for it.

[Eldron]

Doh. I was wrong....so I hid my ignorance :-)

 

Edit: I did find this: https://www.assolutions.ca/flat-mount-caliper-to-post-mount-adapter-guide/

Edited May 18, 2020 by Eldron

[ACE Cycles]

On 5/18/2020 at 2:23 PM, splat said:

Some for sale here:

 

https://bikehub.co.za/classifieds/item/mountain-bike-brakes/1641/flat-mount-brake-to-post-mount-frame

 

@Ki11gar you still making these? 

[100Tours]

As a contrary solution - buy a pair of Magura calipers. Work with Shimano (mineral oil) levers, and absolutely no disk rubbing. Magura caliper and disk on a shimano lever makes the best disk brake solution you can find.