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Discussion Starter · #1 ·
I got a new bike that came with RT66 rotors in 180 front and rear. My old bike had RT86's in 203 front/180 rear.

I moved the adapter (SM-MA-F203P/P) from my old bike to the new bike and swapped rotors between the wheels so I could have my 203 front. Old bike had 985 XTR, new bike has 8000 XT.


Now neither wheel will fit. With the adapter on the new bike the rotor barely enters the caliper and on the old bike the rotor is too tall to fit. Old bike is 142x15 front, new bike is 148x15 (don't think this matters but thought I'd mention). New bike has a Fox 36, old bike has Pike. No adapter should take a 180 rotor, no? And why does a Fox 36 with adapter not fit a 203mm rotor?


What am I missing??
 

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If I'm thinking through this right, your Pike was 160mm native which would mean the adapter was a 40mm spacer to fit the 203 rotor. If your Fox 36 is 180mm native, the required adapter would be the 20mm adapter.

As far as the rear, it depends on what rotor size the manufacturer intended stock that would determine what, if any, adapters are needed.

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Discussion Starter · #3 ·
If I'm thinking through this right, your Pike was 160mm native which would mean the adapter was a 40mm spacer to fit the 203 rotor. If your Fox 36 is 180mm native, the required adapter would be the 20mm adapter.

As far as the rear, it depends on what rotor size the manufacturer intended stock that would determine what, if any, adapters are needed.

Sent from my Pixel 2 using Tapatalk
Is the Pike really a 160 native? I guess that would explain it. I was sure that my Pike was 180 native and the SM-MA-F203P/P I had was a 20mm riser but it's 43mm.

I guess I need a 20mm adapter to get the 180 to fit my old bike AND a 23mm adapter to get the 203mm rotor to fit my new bike.

In case anyone comes across this thread:

SM-MA-F180P/P2 is a 20mm adapter
SM-MA-F203P/PM is a 23mm adapter
SM-MA-F203P/P is a 43mm adapter

160mm post mount + 20mm adapter = 180mm rotor
180mm post mount + 23mm adapter = 203mm rotor
160mm post mount + 43mm adapter = 203mm rotor
 

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Friend of mine has a couple of year old Pike and it's 160 native, as is my Yari. Your description fits too. Sounds like you're on the right path now.

Sent from my Pixel 2 using Tapatalk
 

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Discussion Starter · #5 ·
Friend of mine has a couple of year old Pike and it's 160 native, as is my Yari. Your description fits too. Sounds like you're on the right path now.

Sent from my Pixel 2 using Tapatalk
I thought all this time my adapter was a 20mm (or 23?) but it was a 43. Just ordered new adapters. Thanks
 
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