Jump to content

XTR Front Caliper: ISIS to Post Adaptor


Titanium Rocket

Recommended Posts

Difficult to keep this one simple, but here goes:

 

1.  My old Fox fork had the ISIS mount, so I have an ISIS mount XTR caliper which fitted and worked perfectly.

2.  Recently acquired a new Fox fork, but with a Post mount for the brake caliper (apparently the more popular system these days). The LBS gave me the appropriate XTR adaptor for a 120 mm rotor; with a few shims, I got it all fitted fine.

3.  Now after 6 months of use, and I see that the pads are only making +/- 80% contact with the rotor; the outer 20% of the pad is totally un-touched.

4.  The adaptor is obviously setting the caliper too far away to make full contact with the rotor. I have checked: it is the right adaptor for a 120 mm rotor. Also, there are no superfluous washers setting it too far out.

 

I can actually feel that my front brake power is poor. Does anyone have any ideas how I can claim my un-used 20% of potential stopping power:

1.  I could file down the post mounts on the fork (obviously highly dangerous).

2.  My LBS says "...just buy a new XTR post-mount caliper..." (easy for them to say).

3.  Or I could go to an engineering shop and get them to make a precision adaptor (will be costly).

 

Has anyone experienced this problem? JB - any ideas?
Link to comment
Share on other sites

Hi,

 

 

 

I take it you mean 160mm rotor? First question; it shouldn't matter but, is the adapter a genuine shimano adapter or a 3rd party adapter? In my experience some cheap 3rd party adapters etc are seldom manufactured to IS specs.

Link to comment
Share on other sites

You do not get a 160mm to 160mm IS to mount adapter. You will have to get a A2Z adapter that will make you use a 180 front rotor.

Link to comment
Share on other sites

I recently changed from a Suntour fork to a Fox and had to get an adaptor to fit the XTR caliper. Shimano had none in stock and aparently don't make an adaptor for a 160mm rotor (that may have changed). You have to change to a 180mm rotor and I managed to get a Hope adaptor and 180mm rotor which solved my problem. But the excersice was not cheap.

Link to comment
Share on other sites

Thanks for the contributions. Summary:

 

1. I did mean 160 mm rotor...nit.

2. Have been told by our local Shimano agent that Shimano don't make a 160 mm adaptor for this. Believe I have a generic one.

3. Appears the only way is to change to a 180 mm rotor, and shift the caliper outwards by adding washers / spacers, until it matches the diamter of the rotor.

4.  Am a very fussy fellow...possibly rather just buy the correct Post-mount caliper....and do the job properly.  
Link to comment
Share on other sites

CRC have a special on a XT caliper for R630, post mount. I bought a XTR caliper from them for only R370...

Link to comment
Share on other sites

  • 2 weeks later...

I have the exact same problem - KNC & A2Z Adapter were supposed to work with a 160mm rotor, I can confirm that it does not work.

Adapter and 180mm rotor the only way to solve the problem!

On my way now to buy a 180mm XTR Rotor (R600) eish....

You also cannot seem to get postmount XTR break system from Shimano, you have to wait 6 weeks!!!

 

sharkysa2009-06-05 04:28:00
Link to comment
Share on other sites

Sharkysa, you are on the money. Neither th A2Z or KCNC adaptors align the XTR 160 mm rotor properly, you must increase to a 180 mm rotor.

 

I have decided to go the other way because I want to eliminate the chance of a misfit forever: I have bought a XT post mount calliper. Only R200 more than an XTR 180 mm rotor you are talking about. Post calliper for Post fork - no more incompatibility, end of story, sleep tight.
Link to comment
Share on other sites

That's the best solution! But I will now have some serious breaking capability on the front.....plus some extra grams!

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Settings My Forum Content My Followed Content Forum Settings Ad Messages My Ads My Favourites My Saved Alerts My Pay Deals Help Logout