Idiotic questions

Tazio · Jul 4, 2012

As my move to the scary world of disc brakes picks up speed the more I realise how little I know about them. Specifically the difference between mounts. People keep using terms like IS and post.

What does it all mean? I see the mount on the rear triangle of frames and the mounts on forks and they all look the same to me. What am i not getting?

Forgive me, I'm old

Andy B · Jul 4, 2012

You can have either mount on the fork or the frame

You can get adaptors for most mount combo's, but some may require a larger than 160mm rotor IIRC

Tazio · Jul 4, 2012

Riiiiggght!

So it appears that IS is indeed more standard as I've never knowingly spotted post mount.

This could be a confusing few weeks

Andy B · Jul 4, 2012

Tazio":9b2saizh said:
Riiiiggght!

So it appears that IS is indeed more standard as I've never knowingly spotted post mount.

This could be a confusing few weeks

Post mount (PM) is popular again, mostly found on forks, but now on frames too.

But it has the issue of being able to strip the threads in the frame or fork, meaning helicoil time!

IS doesn't suffer with this issue, but caliper alignment can be a little trickier than PM

Tazio · Jul 4, 2012

Andy B":anev11e3 said:
IS doesn't suffer with this issue, but caliper alignment can be a little trickier than PM

Excellent, more stuff for me to make an arse of

I'm quite looking forward to it now, no more wincing at the sound of rims being eaten on nasty days.

Andy B · Jul 4, 2012

Tazio":gwd12gvw said:
Andy B":gwd12gvw said:

IS doesn't suffer with this issue, but caliper alignment can be a little trickier than PM

Click to expand...

Excellent, more stuff for me to make an arse of

I'm quite looking forward to it now, no more wincing at the sound of rims being eaten on nasty days.

Yup, no more rims being eaten

just brake pads instead

Oh have a look at http://www.parktool.com/blog/repair-help for tips

Tazio · Jul 4, 2012

Cheers Andy, that Park link is superb.

danson67 · Jul 5, 2012

Does anyone know where I can find standard dimensions etc for post mount?

IS standards I can find, but PM seems elusive.

All the best,

cyfa2809 · Jul 5, 2012

51mm?

Otherwise it will vary (as to what size rotor) by manufacturer if thats what you mean.
Its essentially what size 'stub'there is.

danson67 · Jul 5, 2012

Thanks Cyfa.

I've got a project that needs a disc mount, so I've got an Anvil FengShui to fit IS:

but I was fancying a neater postmount like this:

Looks like there's no Standard :cry:

All the best,

Idiotic questions

Tazio

Andy B

Tazio

Andy B

Tazio

Andy B

Tazio

danson67

cyfa2809

danson67

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