flat- or postmounted brake calipers for the FR-603 frame ?

[tlmadsen]

I am lurking around building an all-year/all-weather bike, based on the FR-603 frame.

It has room for wider tyres and mudguard studs, compared to a “pure” racing frame.

A Shimano 105 group-set with disk brakes seems to just have been released and perfectly fits my requirement. However as always, their seems to be a (small) fly in the soup.

The 105 group-set comes with flat-mounted brake-calipers (BR-RS505). Looking at the FR-603 frame, it has “studs” for the brake calipers, with at least to me are for post-mounted brake-calipers.

I asked one of the Chinese suppliers of FR-603 about this and he clams that the BR-RS505 would fit, so now I am slightly confused.

So the questions are


A. Is the FR-603 frame for flat- or postmounted brake calipers ?

B. Can the BR-RS505 brake calipers be used on the FR-603 frame with some from of adaptor ?

C. Can’t any post-mounted brake caliper (from MTB) not be used, if the FR-603 frame is for post-mount ?

D. And is such an adapoter is used, will the "move" the brake-caliber away so a bigger rotor-disc is needed ?

E.Anything else I should know about the FR-603 frame, please come forward...


English is not my native language, so if something is unclear I do apologize.


BR

Thomas

[karstenhorn]

Hi Thomas

By looking at the mounts for the callipers from the pictures you attached and comparing them with the installation manual from Shimano I would say that they DO NOT FIT. It seems like the FR-603 frame uses ordinary MTB callipers and Cyclecross callipers are mounted differently and especially at the rear where they are bolted from under the frame and up into the calliper.

Here you have the manual if you don't got it already:

https://www.google.dk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=12&ved=0ahUKEwjH2Oq50e7PAhUHI8AKHQoIBmkQFghkMAs&url=http%3A%2F%2Fsi.shimano.com%2Fphp%2Fdownload.php%3Ffile%3Dpdf%2Fdm%2FDM-BR0008-02-ENG.pdf&usg=AFQjCNH9rByJIATIh-2eO2gQXKkU25o4Jg&sig2=lfYVf_XeJbDPCY7ifZh8dQ

Good luck with your purchase

Karsten

[tlmadsen]

Hi Karsten

It is clear tha that the flat-mounted caliper like the BR-RS505 is intended to be mounted "flat" on the fame and with bolts going all the way through the frame (at least for the rear breake.). However, looking at the manual you refer to, it clearly shows the BR-RS505 being mounted onto some form of  "adaptor", that in my view turns them into post-mounted calipers (page 42 and 44), so it is still not clear to me if they will work or not.

Why should Shinamo show this option, if it was not to make them "post-mounted" ?

BR

Thomas