160 to 140 rotors.

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This topic has 10 replies, 6 voices, and was last updated 4 years ago by alongo.

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160 to 140 rotors.
alongo
Free Member

I have just acquired a nice spare set of wheels for my gravel bike to use on the road. The bike is fitted with Shimano GRX brakes with 160 mm rotors , the new wheels have Shimano ice tech 140 mm rotors. I weigh 70 kg and feel the 140 mm will be fine on the road.
Is it just a case of flipping the post mount bracket round the other way to accomadate the 140 mmm rotors.

Posted 4 years ago

steve_b77
Free Member

Nope, you’ll be very lucky if you can’t get PM to work with 140mm. AFAIK 140 only works with flat mount

Posted 4 years ago

alongo
Free Member

Thinking about it , if I make both wheels : 160 front and 140 rear it will just be a case of a straight swap whenever I change the wheels. If this sounds feasible I just have the rear adaptor to sort out – will it just flip round to fit 140 , cheers .

Posted 4 years ago

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simondbarnes
Full Member

If the brake is mounted using an adaptor with 160mm rotor then take that off and bolt caliper directly to frame / fork

If there is no adaptor then you are stuck with 160mm min

Posted 4 years ago

scotroutes
Full Member

As Simon says, if there’s a PM-to-PM adapter on the frame then you should just remove it and mount the caliper to the frame.

Posted 4 years ago

jkomo
Full Member

Watch out for the bolt length.

Posted 4 years ago

whytetrash
Full Member

Yep 140 post mount ok with no adapter..its what I’m using currently

Posted 4 years ago

alongo
Free Member

I cant figure out how to load pics. Forks look like I just need to swap adaptor which says 160 top on outside. The rear is also on an adaptor plate but not showing any numbers.

Posted 4 years ago

simondbarnes
Full Member

I’ve just read the original post properly – if they’re GRX brakes then they are flat mount, not post mount. The front will indeed just need the adaptor flipping around. IIRC, the rear will need the adaptor removing and the caliper mounting directly to the frame – a while since I looked at one though and can’t remember if you’ll need different length bolts.

Posted 4 years ago

alongo
Free Member

Thanks simondbarnes , think I’m getting my head round it now. I’ve got the tools required to swap the rotors round . I think I will go with 160 front , 140 rear then it’s just a case of switching wheels when necessary. So , no need to touch the fork , the rear needs the plate taking out which is 6 or 7 mm thick . Will I need shorter bolts or will they be ok?

Posted 4 years ago

alongo
Free Member

Got it all sorted now, swapped rotors round, took mounting plate out and bolted caliper to frame.Bolts were right length and got the circlip on . Got two pairs of wheels to swap around now, thanks for advice everyone,

Posted 4 years ago