Which disk brake caliper do you need? Flat mount or post mount caliper

Which disk brake caliper do you need? Flat mount or post mount caliper. In this video, I show the incompatibility of a flat-mount to a post-mount bike frame or fork. I learned that an adaptor or spacer is not available to provide Flat mount caliper to a post-mount style bike.
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Please watch: "Let's bench test the rear derailleur and see how it moves."
• Let's bench test the r...
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[@TomWilson8003]

Great video. Well done! Thank you.

[@BikeTeacher]

Thank you Tom!

[@lanceblack888]

It’s a total racket. They could have started with flat mount instead of obsoleting post mount. Bikes now cost as much as cars and bike components cost more than automobile parts. It’s a massive fraud. A bike should last a lifetime, not a few years!

[@parasharkchari]

To that end, there should never be any bike or fork with flat or post mounts. They should all just use I.S. mounts where there are no threads cut into the frame or fork. Just eyelets that you bolt your caliper bracket onto. Yes, you can still potentially cross-thread or strip threads when installing, but with I.S. mounts, the damage is at worst to your mounting brackets, which are cheaply replaceable. With post and flat mounts, the threads are cut into the two most expensive parts of the bike, which, if you make a mistake when servicing and reinstalling, means you throw the whole darn thing in the trash. Nothing good could come out of that. I.S. mounts should be the only mount. Anything that involves threads cut into the frame is asking for trouble -- yes, I'm including BBs as well; the issue with press-fit BBs creaking is a result of the need for near perfect machining tolerances, which are unfortunately not achieved by the majority of manufacturers, especially not on carbon frames.

[@Mexxx65]

200th Like! Great info in this video.

[@fandyyoediarto5659]

I have hybrid road bike , with flat mount frame. I want to change the mechanical caliper with hydraulic caliper,which better, using the caliper post mount from mtb (post mount)with adapter... or using roadbike caliper and i must change the dropbar lever to flat bar..

[@MThomasHoff]

Having the same issue on my Breezer Inversion 40th Anniversary.....Help us out Shimano!!!

[@ThePhilematologist]

Thanks for the video are they the same front and back? Or do you need a specific one for the front

[@BikeTeacher]

Front and rear Should be the same on every bike.

[@ThePhilematologist]

@@BikeTeacher thank you. Tom

[@NDURcycling]

short question, i have a bombtrack Hook ext frame and GRX flatmount breaks. The Screws in the back for the rear calliper are way too long whats the problem?

[@BikeTeacher]

Try adding washers, if you ave xtra conical washers, ad them. or get a sorter caliper bolt.

[@maricristsuha7328]

Try Shimano Post Mount Hydraulic Disc Brake Caliper BR-RS785. Same problem with my gravel bike because i have a post-mount frame and GRX is only flat-mount.

[@BikeTeacher]

Thanks!

[@coachman30555]

That's why the rs-785 pm specific hasn't upgraded since 2017, it's for older frames, like having an apple phone from five years ago. Every wireless update makes it slower and slower.

[@BikeTeacher]

Similar situation is the treaded bottom bracket. It’s reuse os endless compared to press-fit frames.

[@fernandocruz9243]

hi there, thanks for the nice and informative video, can you tell me what is the size of the bolt used for ultegra rear brake? mine got loose thread, im gonna need longer size bolt but could not find its size in terms of thread and diameter. pls help.. thank you in advance..

[@BikeTeacher]

Hi. Sorry I do not know the size. Maybe on the Shimano tech websites.

[@mlee6136]

No one even today in 2020 has an adapter from flat to post. I just went through this exercise...tried to fit Ultegra Flat to post. I ordered a couple of adapters from TRP which are supposed to convert them but the holes were not far enough apart and set the caliber too high. In the end I installed a M8000 XT caliber with the Ultegra levers. Bike looks great but the week spending time trying different adapters was frustrating.

[@TheEop1985]

Hi, did you use the m8000 calipers for both front and rear? I currently am setting up hydraulic 105 but I have post mount setup.

[@bikeman123]

Post mount caliper to flat mount frame www.merlincycles.com/shimano-disc-adaptor-post-to-flat-mount-99268.html Flat mount caliper to post mount frame www.assolutions.ca/shop/adapters/flat-mount-brake-caliper-to-160-post-mount-frame-fork-with-160-rotor/

[@gregstinson5725]

A.S. Solutions in Canada

[@Creapture]

I have a flat mount on my 1998 gary fisher? how is it new?

[@BikeTeacher]

I don't know. I am not familiar with it.

[@XXMADBAXX]

Hi, i have a question, i bought the marin team 1, and i try to upgrade the brakes, but de rear brake mount is about 34mm and the usual mounts is about 75mm, which adapter should i use to mount a shimano m6100 brake with a 180mm rotor

[@XXMADBAXX]

Or a 160mm rotor

[@BikeTeacher]

Sorry I do not know those specifics off hand. Check out Problem Solvers website.

[@robertbonner5973]

I believe Paul components makes that adapter .

[@BikeTeacher]

That would be awesome, then you know it's quality. Thanks!

[@henriksvarre4913]

Do you have a link for them? Please

[@JohnSmith-ox7xc]

Not entirely sure I've figured out all the mount types but regarding an adapter for flat mount calipers to post mount frames, I think Wolf Tooth do one - "Post to Flat Mount Brake Adapter " . Not sure if this is what people are looking for in the the comments, it does seem to come with one caveat in order to work.

[@DrPK55811]

I was just looking at the Wolf Tooth. It will allow mounting a 'flat' caliper onto a 'post mount' frame, but it also increases the size of the rotor by 20 mm. I was looking to fit a SRAM flat mount onto my older road frame with a post mount, but I don't need 180 rotors!

[@BikeTeacher]

I have not looked. I would hope something is out by now. Thanks for the info.

[@MrStingraybernard]

Funny I’m looking for just the opposite, I want to use a post mount xt caliper that I already have on a flat mount frame , can’t find an adapter or don’t know the right 1

[@BikeTeacher]

Try Problem Solvers, that make odds and ends.

[@almuntassermohammad7862]

is it possible to make a 35mm flat mount road caliper fit a 75mm post mount mtb frame?

[@BikeTeacher]

There may be adaptors out there by now. I have not had to deal with this for some time. Someone in the past has made a comment and possibly shared a link.

[@Balovante]

i have a problem on my triban grvl120 the front mount is flat and rear mount is i.s. mount, i am looking to replace stock brakes but almost every manufacturer on aliexpress is either selling flat mount or a post mount brake pairs, so my front caliper is supposed to be flat mount and rear one should be post mount. what are my options?

[@BikeTeacher]

Try to find a single caliper only and just install that. I know, easier said than done. Maybe a shop can order for you.

[@Padiatuuu]

why theres still no adaptor for FM to PM frame? couldnt find any solution for this matter

[@BikeTeacher]

I believe in an old comment someone left a link to an adaptor. You may find it if you search for it. I will look as well.

[@BierzeItboxer]

I have a post mount frame and want to buy a GRX group... that's annoying.

[@BikeTeacher]

Take a look in these comments. Someone shared a link for an adapter.

[@BierzeItboxer]

Can't see that for some reason. KZbin says 5 comments but shows only 3... can you repost it? I have post mount on the fork and IS at the frame. Do those adaptors work on both?

[@BikeTeacher]

I looked for it, I can not find that link, the person must have deleted it. I did not save it, sorry.

[@MThomasHoff]

BierzeItboxer www.assolutions.ca/

[@BierzeItboxer]

Thanks! Found that one before and thoght it is a scam... for that money, I get better calipers...

[@andrifujiwara1951]

Why nobody makes an adapter for flat mount caliper to post mount frame?

[@BikeTeacher]

I don't know. I wish someone did.

[@goldo8652]

to sell new bikes and brakes

[@gregstinson5725]

@@BikeTeacher have you looked at A. S. Solutions? I just put Rival brakes on my post mount Warbird with their adaptors

[@kimbirondo9684]

Are all post mounts 74mm?

[@Freedom-Free]

70mm

[@georgestewart5828]

Post mount is 75 mm c to c for the threaded hole on the post. The adapter is 71 mm c to c. There is no ad adapter on the market that has the 75 mm c to c dimension. Hmmmm What is that?

[@BikeLife154]

Well, how about post mount front and flat mount back!!! Good old crack n fail!