Carl J

So, recently ran into a bit of a conundrum with new Fulcrum wheel set that I recently purchased (mentioned in another thread).

Last year I upgraded the 105s that came with the bike, to the newest version of them (R7000). My frame I guess, has IS mounts on it and the hydraulic calipers that came with the new groupset were flat mount. Had to buy a 3rd party adapter to get them onto my bike. All is well, have been riding with them for a year or so now.

A few weeks ago I ordered the Fulcrum Racing 5 DBs, which, have been a complete pain in the saddle. One issue after another. For what I thought would be a simple one day at the shop to get the tubeless set up on them and some minor adjustments, has been over a week now.

Latest problem with the wheels, is that the rotors don't center in the calipers, and there's no way to adjust the calipers either. So the solution I've been told is to go with post mount calipers (and an adapter).

Problem is, trying to find post mount calipers (and ones that would be compatible with my 105s). I keep coming across the Ultegra BR-RS785. But can't find anywhere that sells them, and one site that reviews them is from 2014.

So question is, what options are out there that would be compatible and should be easy to find?

Or would it be easier just to buy a whole new frame that has flat mounts and call it a day?

fietsbob

..Most disc brake calipers are post mount, bikes with ISO frame tabs use an adapter to use the post mount calipers..
(Except for Direct Mount types)

Toronto has Bike shops, No? this hydro brake or cable? cable.. TRP , road the Spyre is dual acting.

Shimano makes cable disc road calipers too..






...

dsaul

I'm assuming that you have the A.S. Solutions adapter, because that is the only adapter that I know of for mounting Flat Mount brakes on an IS frame. Flat Mount calipers are indeed adjustable by loosening the bolts that mount the caliper to the adapter. The mounting holes in the adapter are slots that allow side to side movement. Perhaps your shop is just not familiar with Flat Mount brakes and how to adjust them.

Fietsbob is mistaken in his claim that most disc brakes are Post Mount. Most manufacturers have switched their drop bar brakes to Flat Mount and some have started offering MTB brakes in Flat Mount as well. The switch to Flat Mount has caused issues for anyone with an IS or Post Mount frame, as they are not easily adapted to Flat Mount. .

Carl J

Everything I'm seeing are frame mount calipers. And these are the hydraulic calipers (could go cable, but would mean replacing my shifters too).
Just heard back from the shop, and looks like we're going to go with the Shimano RS785

Carl J

By side to side, you mean forward and back? I could be mistaken, but the issue is/was that they couldn't adjust it in or out (he mentioned as an example, before there were shims that you could add to help make adjustments).

And A.S. Solutions does sound familiar (not a great looking site?). Was the only place that we could find them. So weird!

fietsbob

Hydraulics are about cylinder volume on Master pushing fluid to be split in 2 for the 2 slave cylinders.. and the proportion effecting power ..

you can study fluid dynamics in your spare time..

dsaul

Its not really weird, the two standards are so different that it takes some creative engineering to make an adapter. No other company has even tried to come up with a solution to the problem.

If the mechanic suggested using shims as a way to make adjustments to any disc brake caliper, he is out of touch with modern disc brakes. The slots in the Flat Mount adapter allow side to side movement to center the caliper over the rotor. Front to back adjustment is not necessary unless you are using a different size rotor(140, 160, 180). The A.S Solutions Flat Mount adapter is for use with 160mm rotors. Adapting a Flat Mount caliper to an IS frame with a 140mm rotor is not possible, because the front mounting holes of each standard overlap.

fietsbob

For some reason rotor shims are sold. and someone makes them.

Carl J

No, wasn't saying that the mechanic suggested using shims. Was saying that he told me that he wasn't able to adjust the flat mounted calipers because the adapters have very little adjustability to them (and mentioned that with previous/older calipers, they could use shims, as an example of being able to move them in/out or side to side). I misunderstood what was meant when "side to side movement" was mentioned. And yes, I did have to previously go with 160mm rotors with the previous brakes.

Sorry for any confusion (and hope I didn't make things more confusing)

Carl J

I meant replacing everything with cable, and not trying to mix cable and hydraulics parts together

fietsbob

I have TRP Hy Rd a caliper that is hydraulic, but actuated by a cable..


If you have a hydraulic brifter you just use what they make. (probably not even a MTB hydraulic caliper, from shimano)





\,,,

dsaul

No confusion here. I'm just trying to save you from buying new calipers that you don't need. If it was working before the wheel swap, it will work again. You don't need new calipers, but you might need a new mechanic. If the rotors are the correct size, there is very little chance that the calipers can't be adjusted to center over them. I admit that Flat Mount calipers are a pain to adjust and I hate them, but that is what has been forced upon us.

Elvo

If you're using new rotors, you'll probably need to reset the pistons by pushing them back in with a tyre lever

jp911

Shimano MTB calipers (for example, XT) also work fine with brifters and are still post mount. I have XT and RS785 and can't see much meaningful difference between the 2.