203mm adaptor to a 164mm caliper, will a 205mm disc be ok?
stardude
Posts: 255
hi
i am fitting a new 180 disc to my MPH3 brakes with the special giant adaptor and am already considering what i need to do if i think the 180 up front still needs more oomph by upgrading to 200mm+
this is the adaptor i would use:
http://www.evanscycles.com/products/ashima/is-to-post-mount-adaptor-f-203mm-ec023108?query=is%20mount
now, my caliper uses 164mm discs as standard, so my understanding is that the bracket manufacturers assume you are starting with 160mm discs, so they would just add 43mm of bracket to make it fit a 203mm rotor.
so if i used that adaptor, then surely the 4mm extra gets added to the eventual disc size? so in theory i should need a 207mm rotor?
is that right?
if so, i think i can get away with using a hope C2 205mm rotor (the C2 is the model that Giant made into the MPH brakes, so will have the same braking areas) the current 164mm rotor that i am using has 2mm of the braking surface on the outside edge that isnt even in contact with the pad so i think the 205mm should be fine.
what do you think? does that seem right? or have i just had a huge brain fart?
cheers
adam
i am fitting a new 180 disc to my MPH3 brakes with the special giant adaptor and am already considering what i need to do if i think the 180 up front still needs more oomph by upgrading to 200mm+
this is the adaptor i would use:
http://www.evanscycles.com/products/ashima/is-to-post-mount-adaptor-f-203mm-ec023108?query=is%20mount
now, my caliper uses 164mm discs as standard, so my understanding is that the bracket manufacturers assume you are starting with 160mm discs, so they would just add 43mm of bracket to make it fit a 203mm rotor.
so if i used that adaptor, then surely the 4mm extra gets added to the eventual disc size? so in theory i should need a 207mm rotor?
is that right?
if so, i think i can get away with using a hope C2 205mm rotor (the C2 is the model that Giant made into the MPH brakes, so will have the same braking areas) the current 164mm rotor that i am using has 2mm of the braking surface on the outside edge that isnt even in contact with the pad so i think the 205mm should be fine.
what do you think? does that seem right? or have i just had a huge brain fart?
cheers
adam
0
Comments
-
what fork fitting?
what caliper fitting?
looks like you just need an IS to IS +20mm adapter to go to 185 or a IS to IS +40 for a 205 disc.
Not the one you have linked to."Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
Parktools :?:SheldonBrown0 -
the fork is a post mount REBA
the caliper is a IS MPH3
so i need an IS to Post mount Adaptor0 -
Ok so that adapter you linked will be fine for a 205mm disc."Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
Parktools :?:SheldonBrown0 -
I fitted a 203mm adapter to my Giant MPH3 brakes with a Reba fork, but I went for the A2Z kit.
If I remember correctly, the forks and Giant callipers are both IS fitting, so an IS/IS +40mm adapter is what you need.
EDIT: (Just re-read that you have a post-mount Reba, so ignore the IS/IS comment!)
Post-mount fixings go fore/aft. IS fixings go across the bike.0 -
nicklouse wrote:Ok so that adapter you linked will be fine for a 205mm disc.
ok cool, so the fact that its a 164mm caliper as standard does mean that i need 205 not 203?0 -
-
matters little. but you may need to add washers between the fork and the adapter.
Wavey
"Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
Parktools :?:SheldonBrown0 -
nicklouse wrote:matters little. but you may need to add washers between the fork and the adapter.
Wavey
yeah wavey it is :P
why would i need to put in washers? surely that would push the caliper out even further? and i would already be using a rotor 2mm small?
cheers for your help BTW0 -
just mentioning it. as it can be a suprise."Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
Parktools :?:SheldonBrown0 -
nicklouse wrote:just mentioning it. as it can be a suprise.
ahh ok, cool, i'll order a pack of shims if i do get the 205mm rotor.
cheers0
