Anyone know anything about disc brakes?

none, just aesthetics .. might be some aero arguments dunno.

Just the way it looks?

I like the way flatmount returns to the International Standard way of thinking in that putting a bolt in to a threaded caliper or adapter is superior to putting a bolt through a caliper in to a threaded frame

For this reason alone I'd go flat mount.

That said, the front flat mount still bolts directly in to the fork.

^ this. If you knacker the threads it's the threads on a caliper and not the frame. That is the main benefit of flat mount on the rear. Adapters exist to use a post mount caliper on a flat mount frame.

Can you give me a link to an adapter?

http://www.chainreactioncycles.com/shimano-mount-adaptor-rear-post-to-flat-road/rp-prod137893

Just get a flat mount brakeset though.

EDIT: unless you already own a post mount fork..... ughhhh. See below.

I'm with Howard on this but if it's out of stock then a post mount caliper with that adapter for now is fine. That's what I'm using but I do have the intention of buying a flat mount caliper.

Surely then just go IS instead of flatmount?

IMO benefit if any is marginal for us mere mortals cyclist and it's just marketing gimmick to get us to buy more new stuff.

You can't really recommend a standard when there's no calipers that natively fit that standard.

As much as I like IS I also don't miss faffing with shims :)

Ok - can you talk me through how I would set up if I had the following spec:

• Enve Disc Brake CX fork (post mount fitting)
  
• Geekhouse Mudville Disc with Paragon Machineworks flat mount drops
  
• Shimano ST-RS685 levers with RS805 flat mounts
  
  

What do I about the fork? Just buy an additional post mount caliper and fit that?

Sorry for the world's dumbest set of questions - I know nothing about discs.

So get a flat mount set, rear will be fit without any adapter, front with that one Howard posted.

Obviously it doesnt bolt directly to the IS mount/tab and it does need an adaptor but I wouldnt say it is a faff to get it fitted - just bolt it and adjust your caliper. Still the most common standard and parts are aplenty, what's not to like?

Oh yeah, the flatmount facing tool - WTH is that? Adds weight to my point that it's just a marketing ploy!

Oh yeah, the flatmount facing tool - WTH is that? Adds weight to my point that it's just a marketing ploy!

This is invalid in road disc discussion :)

da-9000-caliper.jpg

Right. Didn't know you already had the Post Mount fork.

This complicates things. Flat mount brakes do not fit Post Mount stuff.

If you can, swap the fork for a flat mount version and buy flat mount brakes.

If you cannot swap the fork, you must get post mount brakes. You'll need an adapter for the rear if the frame is built to the flat mount standard.

If this is a custom bike I wouldn't be happy with the mix of standards TBH.

I'm baffled now.

I thought the adapter @howard posted was for post type disc calipers to flat mount frames, which would allow me to run post type disc calipers with post mount fork and flat mount rear.

What @howard is recommending is to run flat type disc calipers, which doesn't require an adapter if I go for flat mount frame, but leaves me with what to do about the fork.

This complicates things. Flat mount brakes do not fit Post Mount stuff.

Really? I thought they do with an adapter ..

I might've made a huge mistake :P

@Howard is the disc brake oracle, listen to him not me.

what's not to like?

Looks gash. Forces framebuilder to add bracing to the rear of the frame. Limits rotor size front to >= 160mm. In the future, you will not be able to buy a road specific caliper for your road / CX frame.

I think, might be wrong on all of those apart from the looking shit bit :)

Really? I thought they do with an adapter ..

Can you show me one?

I can't find any, and physically it would require some serious negative shimming.

yeah you are right, glad I went flat mount (frame and brakes).

Thats a bit crappy though, I thought shimano would make it backward compatible.

@T-V kinda off topic but CX1 post mount disc groupset is in stock at merlin: https://www.merlincycles.com/sram-force-cx1-11-speed-hydraulic-disc-brake-groupset-83682.html

Why is the idea of using Shimano ST-RS685 levers, with RS875 post mount caliper for the fork and RS805 flat mount caliper for the frame a non starter?

If technically possible, the frame would then be flat mount and I could up grade the fork as and when a flat mount became available.

I thought the adapter @howard posted was for post type disc calipers to flat mount frames, which would allow me to run post type disc calipers with post mount fork and flat mount rear.

Correct.

What @howard is recommending is to run flat type disc calipers, which doesn't require an adapter if I go for flat mount frame, but leaves me with what to do about the fork.

Correct. Your approach will work fine. I didn't know you already had the PM fork.

Magura HS33 ftw!

Why is the idea of using Shimano ST-RS685 levers, with RS875 post mount caliper for the fork and RS805 flat mount caliper for the frame a non starter?

You could do that - there's some hassle involved in sourcing the new caliper and fitting it. Are the pads compatible between the two? Might be worth checking that.

Technically I don't have the fork yet - but what flat mount CX fork options exist? Marty mentioned No.22 fork, which I guess is the one here:

https://22bicycles.com/collections/bikes/products/broken-arrow?variant=2114866881

I can't find any more info on the fork spec though. I am going to try and call Marty later to discuss.

None officially by big manufacturers .. most framebuilders are offering painted Aliexpress offerings I imagine. The only two I know slated to release are Enve Gravel and Mason Aperture 2.

but what flat mount CX fork options exist?

If they don't exist now, they will do soon. Post Mount for road & CX stuff is an aberration.