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Help : Flat mount Road caliper on a Post Mount frame?
Hi. Just about to buy a Synapse frameset with post mountings for disc and most of the Shimano Road Hydraulic calipers on sale appear to be flat mount. Is there a way to mount a flat mount caliper on a post-mount frame and what adapter do I need, please (140mm disc)? ( I know the opposite is possible - post mount caliper on a flat mount frame)
If you're new please join in and if you have questions pop them below and the forum regulars will answer as best we can.
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12 comments
I can confirm that the adapters from A.S. Solutions work! At least on my Specialized Crux 2017 frame with the new Sram Force AXS flat mount brakes. Got the 140-160mm adapters (as I run 160 brake discs) and they were super easy to install.
So just leaving this comment here in case anyone else considers getting them at it is getting increasingly hard to find post mount road calipers.
This adapter from a.s. solution might work. I have IS mount and was not convinced to pay the shipping to Europe yet.
https://www.assolutions.ca/product-category/adapters/
Will this fit?
image.jpeg
Ive got the r785 calipers on two bikes and have never caught my heal on the banjo connection
Infact my heal would hit the frame before the banjo connection
The rs785 caliper does have the bleed nipple at the back of the caliper rather than at the front like on the r785 caliper so they will be a little easier to bleed
Another thing to remember as these are basically xt calipers it means you dont have to run the shimano pads, there are plenty of alternatives out there along with rotors
My current set up is hope rotors with superstar components pads
These work just as well as the shimano rotors and pads but the hope rotors were £40 for the pair rather than £40 each for the ice tech ones
Same goes for the pads, superstar pads £8 (for 2 calipers) shimano ice tech pads £16 (for one caliper)
Have done over 3000 miles on this set up on one bike and they have been faultless
Many thanks for the tips - good to know!
Many thanks for all the help. Looks like they aren't backward compatable then which is a shame as the flat mount units would only seem to need an adpater that lowers them - perhaps the frame too often gets in the way. Still plenty of the RS 785 units around on Amazon which I am going for instead of the R785 units (which have the Kev-s kindly pointed out are the XT -rebadged units). They are still post mount and the pipe run into the RS caliper is better than on the R
There is a buyers guide on this site about disc brakes. This has a picture of a black/green synapse fork with the front caliper on it. At the rear, there is an adaptor that the rear of the caliper is bolted to.
Flat mount calipers will only fit flat mount frames
Post mount calipers will fit post mount & flat mount frames with an adaptor
The r785/r685 caliper is a rebadged MTB XT caliper which is widely availible (i have the xt calipers on my mtb & the r785 calipers on 2 road bikes)
It is possible. I've a Synapse Disc and they simply bolt onto an adaptor.
Really? Can you post a pic?
No they aren't compatible that way, but post mount calipers shouldn't be too hard to find. How about these?
https://www.merlincycles.com/shimano-st-rs685-hydraulic-disc-brake-stis-...
Beware that the prices change regularly. I've seen them for £299 at Sigma and PBK recently too.
Looking at my frame which has a Flat mount on the rear and a post mount on the forks, I don't think so. SRAM still do post mount calipers. Or if your going cable and really want Shimano there are some CX calipers about.
(Infact just found some bumpf saying flatmount is not backwards compatable.)