Results 1 to 13 of 13
  1. #1
    mtbr member
    Reputation:
    Join Date
    Feb 2013
    Posts
    213

    From IS to Post Mount: "adapter" and bolt size?

    Howdy, I'm swapping forks, from an old IS Reba to a 2013 PM SID RCT3, and I use a 180mm front rotor. I'm hoping that someone can tell me what adapter/spacer I need, and what size bolts I need for the correct installation. Big thanks.

  2. #2
    mtbr member
    Reputation:
    Join Date
    Feb 2013
    Posts
    213
    For clarity's sake:
    The front brake is XT; it's post mount originally, of course, and I've been using an IS adapter with it on the Reba. To use it on the SID with my 180mm rotor, I'll need the adapter; something like this: Shimano XTR Mount Adaptor Front Post 180mm | Buy Online | ChainReactionCycles.com
    But I'm hoping to find one quickly in the US.
    Also, it looks like the bolts will need to be different sizes if I use the adapter; does anyone know those bolt sizes? (I'm sure I have them in a gear bag, but don't want to strip out the post mounts figuring out the right size...)
    Thanks for any help.

  3. #3
    I Tried Them ALL... Moderator
    Reputation: Zachariah's Avatar
    Join Date
    Dec 2007
    Posts
    4,317
    Magura QM3 works perfectly, for IS-to-post mount adaptation, on all caliper makes with a 180mm front rotor. They are VERY HARD to find...and you may even have to source one from Europe. Here is what it looks like:
    Attached Thumbnails Attached Thumbnails From IS to Post Mount: "adapter" and bolt size?-picture-072.jpg  

    "The mind will quit....well before the body does"

  4. #4
    mtbr member
    Reputation:
    Join Date
    Feb 2013
    Posts
    213
    Yeah... I didn't clarify clearly. I've been using a post mount-to-IS adapter for use on the Reba; now, I've taken the adapter off for use on the SID, and I just need to space the (post mount) caliper off the posts for use with the 180mm rotor.

    I know... it's really simple. Though, my description seems otherwise.

    Anyway, this is what I need: Shimano F180P/P2 Disc Brake Adaptor in Tree Fort Bikes Brake Parts (mtn) (cat208)

    Hopefully I'll pick one up tomorrow at my LBS, and the mounting hardware with come with. If not, I'll just toss on an old 160mm rotor.

  5. #5
    mtbr member
    Reputation:
    Join Date
    Sep 2011
    Posts
    732
    I just switched from 180 to 160, dont know exactly what the bolts were, but I believe one was a m6 30mm and the other one was a bit longer. Maybe M6 x 40mm?

    the 160 use an m6x25mm

  6. #6

  7. #7
    mtbr member
    Reputation:
    Join Date
    Feb 2013
    Posts
    213
    Loads of thanks for the info. None of my LBSs had one in stock, so I had to order one; got it through the shop, since they help me out a ton. And it'll be here tomorrow.

    By the way, if I ordered online, I'd get the one from Tree Fort, linked in my post above; it's 10 bucks, and comes with all mounting hardware. As cobba linked, looks like you have to order the bolts separately through Bikeman.

    In the meantime, I just swapped my dandy Icetech 180 for an old Avid 160. It works fine, as testified by other folks on threads here. Of course, it doesn't stop as well as the 180, but well enough to let me try out the new fork yesterday before the deluge returned. Jeez... Pittsburgh rain.

  8. #8
    mtbr member
    Reputation:
    Join Date
    Feb 2013
    Posts
    213
    Cobba: Thanks for the link to the Shimano docs. Too bad they don't also specify bolt length, rather than just "long" and "short."

  9. #9
    rebmem rbtm
    Reputation:
    Join Date
    Apr 2007
    Posts
    2,976
    Quote Originally Posted by Collins View Post
    Cobba: Thanks for the link to the Shimano docs. Too bad they don't also specify bolt length, rather than just "long" and "short."
    You didn't look hard enough.

    Part #26 & part #27 on the second document, sizes are shown in the description and a drawing of them is in a box on the left hand side, these are the 2 bolts I linked from bikeman.

  10. #10
    El CicloPath!!!!!!!
    Reputation:
    Join Date
    Nov 2012
    Posts
    248
    The shimanos come with the bolts

  11. #11
    mtbr member
    Reputation:
    Join Date
    Feb 2013
    Posts
    213
    Correct on all accounts. Thanks again.

    Though, it would be great if Shimano would just label the length of the bolts on the adapter doc. Why not? As is, one must x-ref; then, the adapter doc names the part SM-MA-F180 P/P2, and the brake doc names it SM-MA-F180 P/P. Strictly speaking, that's not the same part number, and could lead to more confusion.

    But whatever. I'm leaving work early to ride in some slick clay mud. Peace.

  12. #12
    RIP Friendgirl
    Reputation: Bordershy's Avatar
    Join Date
    Jan 2004
    Posts
    363
    Shimano might not spec length of bolts due to different depths of post mounts. Same with thread depths of IS calipers.
    SPD pedals are an absolute menace to the well-being of the world, and ought be banned immediately.

  13. #13
    rebmem rbtm
    Reputation:
    Join Date
    Apr 2007
    Posts
    2,976
    Quote Originally Posted by Bordershy View Post
    Shimano might not spec length of bolts due to different depths of post mounts.
    The bolt lengths are shown in one of the documents I listed above and the bolts would fit all post mount forks when used as shown in the document.

    Quote Originally Posted by Collins View Post
    Though, it would be great if Shimano would just label the length of the bolts on the adapter doc. Why not? As is, one must x-ref; then, the adapter doc names the part SM-MA-F180 P/P2, and the brake doc names it SM-MA-F180 P/P. Strictly speaking, that's not the same part number, and could lead to more confusion.
    It's the same adapter shown in both of those documents, the old SM-MA-F180 P/P adapter is a totally different design to the newer SM-MA-F180 P/P2 adapter.

    Name:  l_Shimano%20SM-MA-F180-P%20Adaptor.JPG
Views: 1004
Size:  19.7 KB

    Name:  shimano-sm-ma-f180-p-p-disc-brake-mount-adapter__00543.1331467260.1280.1280.jpg
Views: 1636
Size:  26.5 KB

Similar Threads

  1. Replies: 3
    Last Post: 03-01-2013, 10:15 PM
  2. Replies: 10
    Last Post: 09-29-2012, 11:59 AM
  3. Replies: 5
    Last Post: 06-07-2012, 10:18 PM
  4. Replies: 16
    Last Post: 08-06-2011, 01:52 PM
  5. How to know which "standard post mount" size to get?
    By kreal in forum Shocks and Suspension
    Replies: 4
    Last Post: 07-19-2011, 09:34 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •