Showing my age - GRX flat mount calipers on post mount? What adapters?

[accordvsick]

So I have the day off, kids are in school, wife is at work. Which means I have a couple of hours to continue my Ave Maldea build.

Brake Day! : I decided to go with GRX Calipers (got a good deal on a DI2 GRX Lever/Caliper set).

I bought some post mount adapters from amazon (https://www.amazon.com/Micro-Trader-...8-1&th=1&psc=1) which I have on my other 2 avid mechanical disc setups.

I have 160 mm rotors front and rear.

I unpack the calipers and realize these look very different than my old AVIDS. Some googling this morning has become a headache. I guess my question is - will there be a economical path (some brackets?) which will allow me to use these calipers on my frame? Any insite or help will be much appreciated. I suppose I can always sell the calipers and get another hydro set which might work well with the GRX levers

[rice rocket]

I.S. mount is dated, but there is a solution if you don't want to stack adapters.



https://bikerumor.com/found-a-s-solu...mes-and-forks/

[velobaba]

I went through the same a while back and found that wolf tooth has an adapter for it:

https://www.wolftoothcomponents.com/...-brake-adapter

Eventually I decided to sell the flat mount caliper and get post mount calipers to keep life simple.

Hope this helps.

Jalal

[nighthawk]

When I was in a similar situation, wanting to use GRX flat mount calipers on a frame with ISO tabs, the only available adapter I could find was:

https://www.assolutions.ca/shop/adap...-for-is-frame/

The issue with this is you need to use a 180mm rotor up front. 160 rear is ok. Also, worth checking fitment of the adapter before purchasing, they have a drawing you can print from their website that you can check for compatibility with your frame.

Otherwise, you could try and find some post mount calipers and use the more common ISO to post mount adapter.

Should also add, I have no idea if any other ISO to flat mount adapters are out there now. My search was a few years ago.

[mjf]

Keep the calipers, they're super solid.

If the IS mount the same on the frame as what you're showing on the fork there, you would ideally be using a IS->Flat mount adapter. They're not common, but there is an option at least!

https://www.assolutions.ca/shop/adap...-for-is-frame/

Obviously you'll have to make sure that everything fits as far as rotor size, but these were posted on bikerumor a while back and look like a clean and effective choice. They provide a template that can be printed out so that you can check for frame clearance too.


https://bikerumor.com/found-a-s-solu...mes-and-forks/


Edit:

Looks like everyone had the exact same idea

[sheepbleat]

Congratulations: The Di2 GRX hood is the best hood shape on Earth. This is going to be an awesome build.

If both your fork and frame are IS...

For the fork - A.S. IS to Flat Mount adapter and 180mm rotor.

For the frame - A.S. IS to Flat Mount adapter and 160mm rotor.

The Wolf Tooth adapter looks great but it's for Post to Flat Mount. The photos you have shared show IS.

[unterhausen]

IS mounts still come on a lot of bikes. My LBS hates flat mount so much, they told me I should just use IS.

I don't like the idea of stacking adapters. The problem with a lot of adapters is they want to fit down in a recess in the mount, which doesn't always exist. Just going to a bigger disc is something that hadn't previously occurred to me.

[.RJ]

If you dont want to go up in rotor size to accomodate, Im fairly certain you can swap a shimano MTB caliper in, and those are all post mount. XT is probably the best match.

[rice rocket]

Originally Posted by unterhausen

IS mounts still come on a lot of bikes. My LBS hates flat mount so much, they told me I should just use IS.

IS brakes don't exist anymore, I wonder why your shop prefers it (other than being able to upsell you on adapters)?

[accordvsick]

Originally Posted by nighthawk

When I was in a similar situation, wanting to use GRX flat mount calipers on a frame with ISO tabs, the only available adapter I could find was:

https://www.assolutions.ca/shop/adap...-for-is-frame/

The issue with this is you need to use a 180mm rotor up front. 160 rear is ok. Also, worth checking fitment of the adapter before purchasing, they have a drawing you can print from their website that you can check for compatibility with your frame.

Otherwise, you could try and find some post mount calipers and use the more common ISO to post mount adapter.

Should also add, I have no idea if any other ISO to flat mount adapters are out there now. My search was a few years ago.

Thanks for the quick responses all and looks like you were successful with these brackets nighthawk - I'll printout the template and check them out. Looks like wolftooth has a solution but would require another bracket to make them work with my old school IS mounts.

[accordvsick]

So I encountered another issue with this build. I'll avoid creating another thread and hopfully folks will see this.

The frame BB shell is 68mm (I just measured it). I am using CK threadfit 24 along with the adapter kit (the two plastic sleeve things that install on each side of the BB). I have installed this on several other bikes before with Shimano hollowtech cranksets (mainly DA and ultegra).

I bought a 1x GRX crankset , put it on and noticed that the spindle seems short. I am able to put the little end cap on and tension it, but not far enough where the little pin needs to engage with the hole.

This is really puzzling to me - are GRX spindles slightly shorter than DA spindles or are GRX cranksets for something wild like pressfit BB's only.

[robin3mj]

I swapped my groupset from old Rival to GRX on my 333Fab this spring and used the AS Solutions adapter up front and got a new rear rocker from Paragon for the rear. Easy as pie.

[accordvsick]

Originally Posted by robin3mj

I swapped my groupset from old Rival to GRX on my 333Fab this spring and used the AS Solutions adapter up front and got a new rear rocker from Paragon for the rear. Easy as pie.

Any pictures of the rocker from Paragon (having trouble picturing what this is).

[bshell]

IS brakes do still exist and most thoughtful framebuilders consider the mount superior to flat mount. Yet they are at the mercy of component manufacturer's need to 'change'.

[.RJ]

Originally Posted by robin3mj

I swapped my groupset from old Rival to GRX on my 333Fab this spring and used the AS Solutions adapter up front and got a new rear rocker from Paragon for the rear. Easy as pie.

I dont think this frame uses a paragon rocker, the dropouts look fixed.