post to is vs is to post?

cwah

Esteemed Pedelecer
Jun 3, 2011
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Hello,

I have a 203mm rear disc brake and realised that my adapter is too small for it:


I need to buy an adaptor, I realise that there are 2 almost similar one:
Post to is:
http://www.ebay.co.uk/itm/Disc-Brake-Post-to-IS-Mount-Adaptor-REAR-160mm-180mm-203mm-fits-Shimano-Avid/201417220098?_trksid=p2047675.c100005.m1851&_trkparms=aid=222007&algo=SIC.MBE&ao=1&asc=20140122125356&meid=e08e8deec94b4120b281439297cdcbfb&pid=100005&rk=2&rkt=6&sd=201367499849

Is to post:
http://www.ebay.co.uk/itm/Disc-Brake-Adaptor-Post-to-IS-Mount-REAR-203mm-Rotor-fit-Shimano-Formula-Avid-/201367499849?hash=item2ee2703449:g:jVcAAOSweW5VdKnL

Seller put for both of them:
"allow post mount brake caliper to be used with IS frame"

Do they both work or have I missed something?

Thanks
 

soundwave

Esteemed Pedelecer
May 23, 2015
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this is mine tho not the same as the mount that you have. bought a few b4 i found the right 1 for my calliper.

and the only 1 i could find was from germany:rolleyes:

 

flecc

Member
Oct 25, 2006
53,208
30,608
Hello,

I have a 203mm rear disc brake and realised that my adapter is too small for it:


I need to buy an adaptor, I realise that there are 2 almost similar one:
Post to is:
http://www.ebay.co.uk/itm/Disc-Brake-Post-to-IS-Mount-Adaptor-REAR-160mm-180mm-203mm-fits-Shimano-Avid/201417220098?_trksid=p2047675.c100005.m1851&_trkparms=aid=222007&algo=SIC.MBE&ao=1&asc=20140122125356&meid=e08e8deec94b4120b281439297cdcbfb&pid=100005&rk=2&rkt=6&sd=201367499849

Is to post:
http://www.ebay.co.uk/itm/Disc-Brake-Adaptor-Post-to-IS-Mount-REAR-203mm-Rotor-fit-Shimano-Formula-Avid-/201367499849?hash=item2ee2703449:g:jVcAAOSweW5VdKnL

Seller put for both of them:
"allow post mount brake caliper to be used with IS frame"

Do they both work or have I missed something?

Thanks
You've added wrong headings, both are Post to IS for rear brakes. They will suit if the space between the mounting holes on your frame is 74mm and not 51mm.

The first one is for the listed brake discs of 160mm, 180mm, and 203mm.

The second is for the listed Rotor fit 203mm discs.

The way the seller has listed them makes me unsure which one you want, you really need to know which disc brake model number you have. However, I think the first one is likely to be what you need,
.
 
Last edited:
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You have an IS frame and you want to use a post mount caliper.

So you need a mount that converts IS to Post, and you want to run a 203mm rotor, on the rear.

There are lots of options on brake mounts. Hope very handily produces a list.

http://www.hopetech.com/product/mounts/

Available Mounts:
Mount A-Post Caliper to IS (F-160/R-140)
Mount B-Post Caliper to IS (F-203/R-183)
Mount C-Post Caliper to Post (F-203/R-203)
Mount D-Post Caliper to Boxxer, pre-2010 (F-203)
Mount E-Post Caliper to Fox 40 (F-203)
Mount F-Post Caliper to IS (F-180/R-160)
Mount G-Post Caliper IS (R-203)
Mount H-Post Caliper to Post (F-183/R-183)
Mount J-Post Caliper to IS (F-183)
Mount K-Post Caliper to Post (R -PM 140-PM 160)

What you need is Mount G - Post Caliper to IS (Rear 203)

Because you want to run a post mount caliper on an IS frame with a 203mm rotor.
 

cwah

Esteemed Pedelecer
Jun 3, 2011
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179
www.whatonlondon.co.uk
You have an IS frame and you want to use a post mount caliper.

So you need a mount that converts IS to Post, and you want to run a 203mm rotor, on the rear.

There are lots of options on brake mounts. Hope very handily produces a list.

http://www.hopetech.com/product/mounts/

Available Mounts:
Mount A-Post Caliper to IS (F-160/R-140)
Mount B-Post Caliper to IS (F-203/R-183)
Mount C-Post Caliper to Post (F-203/R-203)
Mount D-Post Caliper to Boxxer, pre-2010 (F-203)
Mount E-Post Caliper to Fox 40 (F-203)
Mount F-Post Caliper to IS (F-180/R-160)
Mount G-Post Caliper IS (R-203)
Mount H-Post Caliper to Post (F-183/R-183)
Mount J-Post Caliper to IS (F-183)
Mount K-Post Caliper to Post (R -PM 140-PM 160)

What you need is Mount G - Post Caliper to IS (Rear 203)

Because you want to run a post mount caliper on an IS frame with a 203mm rotor.
Thanks, again very good information that teaches a lot about the standards.

This little table is great I'll save it somewhere :)
http://www.hopetech.com/wp-content/uploads/2015/10/Hope_Brake_Mounts_2016_Page2.pdf


So I need this?
http://www.ebay.co.uk/itm/Disc-Brake-Post-to-IS-Mount-Adaptor-REAR-160mm-180mm-203mm-fits-Shimano-Avid/201417220098?_trksid=p2047675.c100005.m1851&_trkparms=aid=222007&algo=SIC.MBE&ao=1&asc=20140122125356&meid=e08e8deec94b4120b281439297cdcbfb&pid=100005&rk=2&rkt=6&sd=201367499849

But the mounting hole of my bike is 51mm, not 74mm. Is it still correct?

Thank you
 

flecc

Member
Oct 25, 2006
53,208
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Yes, since as KTM said, you want to run a post mount caliper on an IS frame

Your 51mm says that your frame is an IS one.
.
 
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cwah

Esteemed Pedelecer
Jun 3, 2011
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Actually, on the picture it's an odd shape:


I've never seen a caliper of this shape, but that's correct I suppose?
 

soundwave

Esteemed Pedelecer
May 23, 2015
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that looks like its the right 1 when i got mine could not see it working till i fitted it.

think mine was 18 quid with postage :(
 

flecc

Member
Oct 25, 2006
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Actually, on the picture it's an odd shape:


I've never seen a caliper of this shape, but that's correct I suppose?
That looks perfectly ok to me, there's another one for you that would be ok on this link, looking exactly the same. In both cases, adaptors for post mount brake caliper to IS mount frame.
.
 

soundwave

Esteemed Pedelecer
May 23, 2015
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problem i had was getting the right mount to fit my calliper in the right place.

this is the same bike as mine but different calliper so completely different 203 mount to my avid calliper.

 

soundwave

Esteemed Pedelecer
May 23, 2015
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if you think ur calliper will fit in the space then yes it should work.
 

flecc

Member
Oct 25, 2006
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Yes, it should be fine, it's the same design as the ebay one you linked to. It should accept your post mount caliper and bolt onto your IS frame without any problems.
.
 
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