I’ve been trying to do this for two days but have come up with nothing, was hoping STW might be able to help me out? 😀 I’ve got a Hope Tech m4 brake on the back, and a 203mm rotor, and I bought the correct adapter, Mount G for 203mm rear, but the wheel is locked solid when I wind the bolts down. I’ve tried using numerous combinations of spacers, even 5 per end and pushed the pistons back but it still seems to rub no matter what, my guess is the calliper is sitting at an angle. I really am at a loss, I have no idea what to do somebody please help omg

I know motorman on here has a serious Moonlander he’s down some downhill with 😆

here’s a pic:

I’ve tried using an infinite number of spacers

No you didn’t.

Have you cleaned any paint off the mounting faces of the frame (if there is any)?
If it’s not that then it would just be a case of trial and error with the spacers/washers.
Maybe take the pads out and see if you can tell if the disk isn’t centralized in the caliper. It might also make it easier to tell if the caliper is aligning correctly.
EDIT: another thing to check is that the caliper is not sitting too low and fouling on the top of the disc.

Surly QC isn’t great, some Krampus frames came with the mount welded upside down, i guess the spec of the frame is out, the Hope mount will be fine

beer and **** mainstream brands and all that 🙄

thats an awful rotor btw

and 203mm on the back of a moonlander 😆

Im guessing its touching at the front of the caliper? Due to the geometry of the sliding dropout and disc mount you might need to move the wheel back in the slots a little to get it working properly.

[edit] to expand on that. The slots in the disc mount are shorter than the slot for the wheel, so the ‘perfect’ position of the caliper only applies when the wheel is in a smaller range or position.

If you think of the dropouts as for singlespeeds then your wheel would never end up right at the front, instead you would put it to the front, put the chain on, then pull it back. So that’s where they placed the disc mount, the middle, with a bit of adjustment for tension tweaking.

Of course luckily for everyone with gears, at the extremes of the dropout the centrally placed caliper will still cover the disc, and with 2 piston calipers this is fine, but your 4 piston wraps forward too much so hits the rotor. Find some mokey nuts to pull the wheel back and id suspect all will be well.

Wow, thanks for the replies! Alan, the problem is exactly that, the rotor is so high up on the calliper it won’t move at all!

Haha, dirtyrider Surly say all that, but they are a mainstream(ish) brand! And what’s wrong with my rotor?! 🙁 haha I thought the oversized rotor would look nice with the oversized tyres!

Stato, that’s exactly what it is! I don’t like the sound of that as I’m going to be doing some enduro-ish riding on it (help me!) and the idea of having the wheel hanging in the dropouts scares me!

edit: just tried it, wheel still won’t move at all! The previous owner of the bike was running a 160mm with a shimano adaptor which was working fine, but I was told by LBS the hope adaptors are machined for the calliper to sit completely flat and work much better so got one of those?

monkey nuts

If you don’t fancy having the wheel further back in the dropouts you could experiment with spacers between the mount and caliper to raise it up a bit.
Although it sounds like you might not be getting full pad to disc contact with that. If that’s the case you’ll need to watch out for lips forming on the pads, which will in the end meet and prevent the pads from stopping the disc – it will be when the pads are worn so you’d need to check them regularly.

edit: just tried it, wheel still won’t move at all! The previous owner of the bike was running a 160mm with a shimano adaptor which was working fine, but I was told by LBS the hope adaptors are machined for the calliper to sit completely flat and work much better so got one of those?

Ok, so if that doesn’t work, you need to try some other 203mm mounts. There are differeances in where they position the caliper on the rotor (the only standard is the placement of the holes and that its a 203mm rotor, not where the caliper has to be, you could make a huge U adaptor to hold it under the chainstay if you wanted). Ignore the bollocks LBS spouted, get a shimano one and try that first.

Or get monkey nuts 🙂

Actually, if its still binding then its probably an issue with mis-alignment of the mount as someone previously stated. Post some more pics from different angles so we can get a better look at where its jammed.

I thought the oversized rotor would look nice with the oversized tyres!

I recently fitted a 203mm rotor (and 180 rear) to my Fatty. Oddly it actually makes the calipers look really out of place and the adapters really spindly (despite being Shimano calipers and adapter). Can’t explain why, but it just looks ‘wrong’.

It works though, the traction from the big tyres in a straight line means braking feels more limited by how hard you can push your weight back from the bars than any normal limitation!

Thanks for the advice all, took it down to LBS and the problem is the frame, and the reason it’s rubbing even with spacers is because the calliper mount on the frame, it’s not perfectly straight, could be Surly QC as some of you have said!

and I have been told my rotors are shit but struggled to get an explanation as to why. They just called it cheap shit?

They’ve been called shit because they look shit. Sorry. I can’t comment on the build quality from here but they look a bit boy racer. As an aside, why on earth do you need a 203mm rotor on the back of a Moonlander with such beefy brakes?

Ahh, moonlander. I remember when it was a swear word edit on the Chocolatefoot forum.

Ahh, I see. I thought they looked kinda cool but thank you for explaining. I just got them because like I said, I thought the oversized rotor would look nice with the oversized tyres!

No, no, no! Dinky 160mm rotors make the wheels look even bigger!