Please can someone tell me whats going wrong in the picture below and how to solve the problem? It’ a new frame and a new 40mm mounting adapter. The brake is meeting the rotor, so where I am pushing down in the picture, the caliper will not meet the mounting adapter. Also it looks like the caliper isn’t in the correct position anyway, judging by where the rotor is coming out out the back of the caliper.

All the literature says a 40mm post adapter is the adapter I need for a 180mm rotor.

What’s going on? It’s driving me mad!

Thanks

Does it fit with the adapter on the other way around (arrow pointing to the front)? 😉

Because you’ve got the adapter backwards 😉

Edit: yeah backwards!

As above, arrow points up.

If the adapter is the other way round then it mover the caliper to the left, o much so that there is no way the pads will come into contact with the rotor. This made me think a 20mm adapter is required but I have been told they don’t exist any more

What size rotor is it?

Edit: didn’t read the post – I think 20mm is what you need for 180mm isn’t it?

Longer bolts and washers?

Where are your CPS washers?

have you got a 185mm rotor and the caliper’s for a 180mm one?

[as per ben re-read post]

but don’t sram brakes have lots of washers and stuff?

Given it’s an Avid brake – does it still need the Tri-and-align conical washers of yore?

That could be a front adapter….

Edit: yep, avid should have cup and cone washers?

Adapter upside down, no washers and it’s not an avid adapter so will foul the pads.

Depends on the frame. Some come with a 140mm rear and you need a +20mm adapter for a 160mm rotor

The adapter can’t be upside down, that’s not possible, and it came from merlin I an avid box, so I don’t believe that.

does it still need the Tri-and-align conical washers of yore?

Yes, but these generally go on the outside of the caliper so they wouldn’t affect the caliper’s position in this instance.

How do those washers do anything other than take up bolt length situated where they are?

that’s what I thought. shouldn’t there be at least one of those domed ones under the caliper as well?

If the adapter is the other way round it looks like this

I would also have suggested that the adaptor is back to front (arrow pointing in direction of wheel rotation) and that it’s missing the spherical washers.

But this pic suggests maybe not

what frame is it?

An Evil Uprising?
Edit – and it comes 160mm as standard

edward2000 – Member
If the adapter is the other way round it looks like this

Which looks right for a 200mm rotor which is what I’d have expected to be the case with a +40 adapter. I thought most mtbs with PM rear were 160mm if no adapter was used (while for example, my CX frame is 140mm if I don’t use an adapter).

Hm, some frames are spaced to a ‘direct mount’ for larger rotors. So they’re spaced for 160mm instead of 140mm.

I suspect this is what’s happened here, you’ve got a frame spaced for 160 and added a + 40mm which has taken it up to 200mm spacing. which is why, with the adaptor the correct way up, the Caliper is sitting roughly 10mm too far out.

What model & year frame is it?

*EDIT* Yup looks like you need a +20 not a +40 adapter.

They don’t use the CPS/tri align on the new Avid brakes. So my vote is with the +20mm adapter option.

So where can I het a 20mm adapter from? I rang sram and they said they don’t do a 20mm adapter

Its a front adapter…. someone else mentioned it above

You could try one from another manufacturer but I think the caliper fouls them, hence AVID not doing one?

Why not stick a 160mm rotor on?

CPS washers are needed between caliper and mount as stated in instructions, this depends on whether you have in line or offset tabs, think you might have to read the instructions.

Use a 160 disk and no adapter? Which will be fine.

This from their instructions says use a +20 adapter.

Thats ^ kin ridiculous, could they have made it any more complicated?

Think you need to work out whether you have inline or offset tabs.

00.5318.008.003 seems to be the Avid part number for the spacer kit you need.

You can’t get a 20mm adaptor off the shelf for avids, it’s OEM only. Officialy you need the spacer kit.

I was going to PSA this the other day – the adapter you need is here: http://www.on-one.co.uk/i/q/BSAVPPBM/avid-post-to-post-brake-adaptor

Normally you can’t get them but On One must have bought a load for a build kit. £1.99 each I bought a handful! You will also need longer bolts, so the original spacer kit here will give you those: http://www.chainreactioncycles.com/avid-disc-brake-spacer-set-hardware/rp-prod108156

You could just use the spacer kit but it’s a bit messy.

I can confirm the on one spacer definitely works – ignore the picture it’s not that one you get. I also have X0 trails.

I’ll never understand the bike industry’s obsession with using oddball bolt lengths, non-parallel adaptors and those hideous CPS washers.

OP, you have the wrong size adaptor and it’s fitted the wrong way round. Buy a superstar type 7 adaptor (180mm PM-PM) for a fiver and use that.
http://www.superstarcomponents.com/en/disc-brake-adaptor.htm

In typical on one fashion the photo shows an IS to post mount adapter 😀

OP, you have the wrong size adaptor and it’s fitted the wrong way round. Buy a superstar type 7 adaptor (180mm PM-PM) for a fiver and use that.
http://www.superstarcomponents.com/en/disc-brake-adaptor.htm

Won’t fit. That was what I did first!

How do those washers do anything other than take up bolt length situated where they are?

That is all they do…. SRAM haven’t released that adaptor to the public so if you use the recommended bolts they are too long! Totally half arsed for what you think would be quite a common requirement?

Ok thanks for everyone’s help. I’ve brought a 160mm rotor. Can’t understand why sram would advise a 20mm adapter and not offer them for sale!

Nick, out of curiosity, why didn’t it fit? Did the caliper foul the adaptor?

OP if you still want to run the 180 disc these might work for you?
It seems to be the 20S spacer kit that wwaswas posted earlier.

http://www.chainreactioncycles.com/avid-disc-brake-spacer-set-hardware/rp-prod108156

Thanks Neil