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It's like this see.
I have new forks on the hardtail and suddenly my previous brake set up that I'm transferring over from older forks doesn't line up so well and I'm clearly missing something obvious.
I have a 203 rotor.
I have a 'U5M F203' adaptor.
Forks are Revs, maybe couple of years old.
Previous forks were older Revs.
If I mount the adaptor with the 'UP' marking uppermost, the caliper fits but barely covers the rotor at all. Maybe just about 5mm of the edge of it.
If I mount the adaptor with the 'UP' mark down, the caliper goes on too far and the caliper body, grounds out on the rotor.
Has the actual post mount on forks changed without anyone telling me, or worse, am I missing something blatantly obvious?
Previous forks, older Revs here
We're your previous forks standard 160 without adapters and your new fork is 180 standard without adapter?
You might need a smaller adapter as your starting 20mm further out than before?
Try a 180 adapter for the 203 rotor and see what it looks like.
Quick Google and minimum size is 180
https://www.sram.com/en/service/models/fs-rvl-rc-a2
As above, 180vs160 post mount lowers
Were your previous forks standard 160 without adapters and your new fork is 180 standard without adapter?
Yeah, not sure to be honest.
I didn't actually realise that the standard, cast-in brake mounts came in different standard sizes to be honest.
I expect that's the problem.
I always run a 203 on the front and so must have had an adaptor on the old fork.
The calipers and rotors have come right off the old forks.
As above, 180vs160 post mount lowers
I didn't get that memo.
Not had newer forks for a while 😬
Cheers folks.
Makes sense now.
Knew it would be something fairly obvious 😊👍🙏
I've always had to use a small washer inbetween the brake mount and the brake caliper with 203mm rotors with Shimano brakes. The washer just leaves enough space to stop it rubbing the caliper
Aye, I've had to do that before, but actually never come across 180 standard post mount weirdly.
Aye, I’ve had to do that before, but actually never come across 180 standard post mount weirdly
I'm fairly sure every current fork is 180 post mount as standard now, the revelations went from using the old 32mm stanchions to using the same 35mm stanchions as pikes.
You will probably find that a 160-180 adaptor commonly used on the rear will do the job perfectly well if you have one of those knocking about
Annoyingly, I had a huge box of adaptors that I had for years and years, and got rid a while back!
I've just nicked a 180 disc off my fatty for now 😊👍
I’m fairly sure every current fork is 180 post mount as standard now, the revelations went from using the old 32mm stanchions to using the same 35mm stanchions as pikes.
That'll be it yes.
My old Revs were the 32mm stanchion type.
They look very noodly now, and these new ones are well... a revelation.
actually never come across 180 standard post mount weirdly
I have on the front, but then I bought a new frame and it had 180 mm post mount on the back, so I ended up changing a bunch of bikes over to 180 mm rear so that I can swap wheels if I need to.
I had similar when changing fork; in the end I treated myself to a larger disc.