Disk Mount Questions

Author:  WD Pro [ Mon Nov 01, 2010 2:05 pm ]
Post subject:  Disk Mount Questions

The bike will be built with V’s but could someone confirm what type of mounts these are and what disk sizes they would take as standard ?

Frame :


Fork :


The forks are new but as some details were incorrectly advertised I would like to be sure … :?

Are any dimensions needed off each to confirm ?



Author:  cyfa2809 [ Mon Nov 01, 2010 2:17 pm ]
Post subject: 

frame looks to be i.s (international standard) mount

forks are post mount which is 74mm spacing i believe. most post mount brakes are 74mm :wink:

edit: chances are it will be 160mm discs as standard, after that you get your larger mounts etc.
i know my marz forks (post mount), the caliper went straight onto them and then fitted a 160mm disc
will be the same for the frame unless both your brakes are post mount in which case you will need a pm to is adapter (or vice versa for forks, altough most brakes are now post mount)

Author:  WD Pro [ Mon Nov 01, 2010 2:21 pm ]
Post subject: 

Thanks 8)

Anyway to confirm the rear is defo an IS mount - hole centers etc ?

Should I be looking for mounting hardware to put away for future use or is it all pretty standard / easily sourced ?

Sorry for the thicko questions - I am new to disks (and boingy forks) :oops:


Author:  cyfa2809 [ Mon Nov 01, 2010 2:26 pm ]
Post subject: 

think 51mm for the i.s
(just searching to confirm)
hardware is readily available :wink:

edit: 8) :wink:

Author:  dbmtb [ Mon Nov 01, 2010 9:09 pm ]
Post subject: 

Depends what brakes you buy - it would make your life a lot easier if you buy post mount fitting brakes.

Author:  WD Pro [ Tue Nov 02, 2010 10:23 pm ]
Post subject: 

Sorry for the delay :oops:

Yes, the rear spacing is 51mm :D

Does that mean if I got a IS mount caliper it would bolt straight on ? If so - what size disk is standard for IS ? Or does the spec of the caliper tell you i.e. 160mm and then if I wanted to up size by 20mm, I just get a +20mm spacer ?

Sorry for all the questions, I could really do with an 'idiots guide' ... :oops: :lol:


Author:  dbmtb [ Tue Nov 02, 2010 10:50 pm ]
Post subject: 

Really need to know what brakes you are wanting to fit before can give you a full answer.

What size rotor do you want to run and which brakes are you looking at?

You can buy IS calipers but it's more time-consuming to fit them as you have to fiddle with spacers to center them on the rotor. Most brakes these days are supplied as Post mount fitted onto an IS adapter as standard option.

Author:  cyfa2809 [ Tue Nov 02, 2010 10:51 pm ]
Post subject: 

i think hope tell you the size but if its caliper direct to fork/frame mount without an adapter it should be 160 8)

Author:  dbmtb [ Tue Nov 02, 2010 11:00 pm ]
Post subject: 

Unless you buy an IS caliper that will run 160 on the front - and fit it on the back - in which case you'd need a 140 rotor.

This goes for both Hope AND Shimano.

But as CYFA says - MOST rear brakes without adapters would be 160 or so.

Author:  WD Pro [ Tue Nov 02, 2010 11:57 pm ]
Post subject: 

OK, I think the penny is dropping - at least for the rear :lol:

No plans to fit disks yet, just want to know my options and keep my eye out for cheap bits :D

So if I choose one of these : ... elID=45525

They would bolt straight on and depending on which one I got, would fit a 140 or 160 rotor with no additional bracket ?

What's a good size rear for xc use ?

I like the idea of mounting them with no extra bracket, seems much neater - I spent ages looking for lug mount calipers for the kit car, much nicer when on show 8)

Seems a shame they have to be centred with shims though - would have thought they could have designed them to line up perfectly :-(

Front post mount questions coming up soon ... :lol:


Author:  cyfa2809 [ Wed Nov 03, 2010 12:38 am ]
Post subject: 

yes that will bolt straight onto the back
not the front (you will need an adapter and 180 rotor it seems)
easily available though and 180-160 is a much used combo
in theory you shouldnt have to shim it asd the pads will self adjust but ive had to do it on mine, not by much (1mm washers)
so it will be hit or miss, wont need much spacers if it does, they will sit between the frame and caliper

Author:  dbmtb [ Wed Nov 03, 2010 1:03 am ]
Post subject: 

Just buy the post version for the front....

Depending where you're riding.... 140mm might be OK on the rear but 160mm will give you more options. Had horrendous brake fade on a long descent near Frankfurt a couple of years ago using a 140 and replaced it with a 160 which has been fine.

Personally I prefer a 180 front 160 rear combo. But you've bought a Ti. frame. Weight saving may be more of an issue for you.

Author:  MikeD [ Wed Nov 03, 2010 10:02 am ]
Post subject: 

160/160 is fine for most things, although there's little harm in going bigger at the front. If you're bracket-averse, though, 160 PM front and 160 IS rear is the way forward.

Set aside a decent span of time for putting them together if you get those XTR ones in bits - they're a bit of a pig to bleed.

Author:  dbmtb [ Wed Nov 03, 2010 10:06 am ]
Post subject: 

MikeD wrote:
Set aside a decent span of time for putting them together if you get those XTR ones in bits - they're a bit of a pig to bleed.

Can honestly say there is no point buying M975 XTR brakes. Buy M775 XT instead. You get more adjustment possibilities at the lever. M975 brakes are a nightmare - even when correctly fitted they feel sloppy.

Author:  Scarfacexxx08 [ Wed Nov 03, 2010 2:51 pm ]
Post subject: 

I have XT levers with XTR calipers, but i also run them with Avid G2 rotors and they work alot better than Shimano rotors

Author:  dbmtb [ Thu Nov 04, 2010 12:47 am ]
Post subject: 

Scarfacexxx08 wrote:
I have XT levers with XTR calipers,

Could do that too of course. The calipers are mechanically identical.

Author:  mountainloz [ Thu Nov 04, 2010 10:28 pm ]
Post subject: 

i've just finished building my 99 specialized fsr
at the mo i am running 160/160
i did have a 180 on the rear but it just didnt look right on it
i may end up with a 180 front/160rear eventually as on my mountaincycle, this seems to work for me, but so far the 160s are ok

as for disc size, it all depends on the caliper, my mono mini takes a 160 on the back, but my M4 would take it to a 180
the same M4 i had on my kona stinky with a +20 adapter taking a 205mm

post mount sets up very easily, on the front i have a hope mini, on a 160mm rotor, if i want to go bigger there's a +20 adapter or i could go for a is mount caliper with a post to is adapter

i feel i'm rambling a bit but if you need any help, just ask

it seems between us we have it all covered :)

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