I’ve just installed a set of Formula RX discs on my Yeti ASR. the front is running a 180mm post mount with a Alligator Cutter 180mm disc. The rear is running a 160mm IS mount with a 160mm Alligator Cutter disc.

The rear disc seems to small small for the caliper & mount (ie. not very much of the disc is actually being gripped by the pads) and the front is better, but still only contacting with 70% of the braking area.

What am I doing wrong?

not sure, but I have a Formula RX brakes on my ASR5 and they fit perfectly. That is with a 180mm rotor on the rear, mind.

Is it all new kit? the front has nothing to do with your choice of frame – so i’d imagine if it fit before, it will fit again! (if that makes sense)

i’m wondering whether it is something to do with the rotors… anyone with experience of alligator windcutters?

sure your old rotors weren’t 185mm, and your mount adaptor is the same?

nope… new rotors, new callipers, and the mounts both say 180mm & 160mm on them… the mounts are the correct way up and are front & rear specific.

all part of the same kit? or bought seperately?

take some pics and post them up – might help!

pics?

looking at this carefully, only about 2mm of the inside bottom circular section of the rotor is not making contact, so I guess that is almost acceptable

this on the other hand quite clearly shows that only 50% of the braking surface of the rotor is meeting the pads (and due to the windcutter shape, it is the bladed section rather than a regular circular section

You sure it’s a 160mm rotor?

try the rear adapter the other way around.

Wwaswas. Thats what I thought

the arrow on the back of the adapter is pointing upwards…

even so.

will give it a go… i guess i can put a spacer or two between the mount and the caliper if it fouls slightly… but if it does work, surely the pads will be angled incorrectly against the disc?

I’m pretty sure on my RX rear adapter the side with the size marked on it faces outwards which would suggest this one could be fitted the wrong way round.

i’m not using a formula mount on the back as i only have a 180mm version

I would be surprised if the logos were on the outside rather than facing the wheel

I would be surprised if the logos were on the outside rather than facing the wheel

why, the front mounts that way?

i’m not using a formula mount on the back as i only have a 180mm version

so is it not a 165mm mount then if it isn’t the formula one?

Any luck?

Is the mount for a front brake? The front one says F-180 on it – does the rear say R-160? If it says F-160, there’s your problem.

EDIT: Ignore. A front 160mm adaptor would be too small, rather than too big.

Only a few possibilities left. What size is the rotor? Definitely 160?

Or the wheel isn’t sat in the dropout correctly 🙂