# Shimano Road Disc Brake Adapter For 160mm Rotor?



## Dr.Kildare (Oct 20, 2005)

I want to install a Shimano RS785 disc caliper onto a road fork with post mounts and a 160mm rotor.

As I understand, the calipers are spaced for 140mm rotors out of the box.
I assume I will need an adapter or spacers to space out the caliper for the 160mm rotor.

Both the fork and the caliper are post mount, but I can only find information on an adapter for 160mm post mount fork and ISO caliper.

What am I missing as I can't seem to find the answer anywhere on the net.

Thank you if you can point me in the right direction.


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## cxwrench (Nov 9, 2004)

Calipers are calipers...the variable is the fork/frame. Most are set up for 160mm rotors already. I'd check yours to make sure.


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## Dr.Kildare (Oct 20, 2005)

cxwrench said:


> Calipers are calipers...the variable is the fork/frame. Most are set up for 160mm rotors already. I'd check yours to make sure.


Hi cxwrench, the fork is a Whisky No.7 cross fork (haven't actually got it yet) and it's set up for 140 to 185 rotors, so I assume that anything above 140mm needs an adapter. Just like to know what that adapter is for 160mm.


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## zyzbot (Feb 3, 2004)

Dr.Kildare said:


> Hi cxwrench, the fork is a Whisky No.7 cross fork (haven't actually got it yet) and it's set up for 140 to 185 rotors, so I assume that anything above 140mm needs an adapter. Just like to know what that adapter is for 160mm.


I don't know if this will help you but I just ran across it:

Shimano Disc Brake Adapters | Competitive Cyclist


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## Mr Evil (Aug 12, 2011)

According to Whisky's site, the No.7 cross fork has "74mm POST MOUNT DISC (160mm-185mm)", which means it won't need an adapter for a 160mm disc.

If it really is a 140mm post mount, then if I may quote myself: "they are generally sold as "180mm" adapters, because they will adapt a 160mm mount to 180mm, but really they are +20mm, and so will adapt a 140mm mount to 160mm too".


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## cxwrench (Nov 9, 2004)

^This^


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## Dr.Kildare (Oct 20, 2005)

Mr Evil said:


> According to Whisky's site, the No.7 cross fork has "74mm POST MOUNT DISC (160mm-185mm)", which means it won't need an adapter for a 160mm disc.
> 
> If it really is a 140mm post mount, then if I may quote myself: "they are generally sold as "180mm" adapters, because they will adapt a 160mm mount to 180mm, but really they are +20mm, and so will adapt a 140mm mount to 160mm too".


Yep, that's the answer.
Thanks for your help
DK


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## SwiftSolo (Jun 7, 2008)

I 've done just what you are suggesting except I converted only my front disc to 160 from 140mm (shimano disc hydro). I bought a shimano shim that didn't work but found a Magura shim that I had in my parts box that worked perfectly. I believe that the shim for the front will not work on the back on my synapse hi-mod (bike's packed so I can't easily look).


Dr.Kildare said:


> I want to install a Shimano RS785 disc caliper onto a road fork with post mounts and a 160mm rotor.
> 
> As I understand, the calipers are spaced for 140mm rotors out of the box.
> I assume I will need an adapter or spacers to space out the caliper for the 160mm rotor.
> ...


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## 92gli (Aug 27, 2009)

Can you show a pic of how that works? My bike has posts for 160. I was under the impression that downsizing to 140 is impossible.


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## SwiftSolo (Jun 7, 2008)

Don't think you can downsize unless there is a shim block that can be removed from under your caliper unit.


92gli said:


> Can you show a pic of how that works? My bike has posts for 160. I was under the impression that downsizing to 140 is impossible.


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## cxwrench (Nov 9, 2004)

92gli said:


> Can you show a pic of how that works? My bike has posts for 160. I was under the impression that downsizing to 140 is impossible.


It will not work. The poster above was probably confused about what he was describing. Unless you machine down the posts there is no possible way to make it work. 

None.


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