BrettM's Rear End

Discussion in 'Observed Trials Discussion' started by trialsbug, Sep 7, 2004.

  1. trialsbug

    trialsbug New Member

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    I have some questions about Brett's rear disc.

    On Brett's Peyto the Avid disc is mounted without an adapter. I believe that this is the 74mm Manitou mounting pattern, correct?

    Does it matter whether this is a front or rear caliper? Are they different or is the mounting adapter the only difference for the front and rear Avid disc?

    I know that the distance from the dropout to the disc mounting surface of the hub is different for the front and rear, but I don't know whether the caliper or the mounting bracket makes up this difference. Did you base the location of the rear caliper on the mounting dimensions used for a front disc caliper?

    These are the only mounting dimensions that I have been able to find:
    http://www.hayesdiscbrake.com/tech.cfm
     
  2. Rob.K

    Rob.K Guest

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    You know you could just PM him..:(
     

  3. xxxfr

    xxxfr RCP FABRICATION

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    actually im glad you brought this up, im interested too...
     
  4. tomacropod

    tomacropod Rum Pig

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    in the absence of any other information, I'm pretty sure it was the "other" standard 74mm post mount - like the manitou forks. Yes this meant he didn't have to run the avid adapter, the caliper mounted straight onto the frame. I don't recall the rotor size but I'd imagine it was aligned for the 180mm rotor. A very clever design if you ask me, I'd say he really has a head for that sort of thing - he's giving a fork a go in the near future as well I believe.

    - Joel
     
  5. redneck_biker

    redneck_biker Guest

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    He dont have disc on anymore. I thought that was why his frame broke. Now its just on the front and he is running a avid mech.
     
  6. AndyT

    AndyT New Member

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    I'm pretty sure hes just riding a koxx..
     
  7. BrettM

    BrettM New Member

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    Ya I am currently on a Koxx for my trials bike. The Peyto is my street bike and I still run rear disk on it.

    You can run a front or rear with post mount. The calipers are the exact same, only the adaptors are different.

    I didn't have to do all the math, Paul at Peyto did. He found a page on www.avidbike.com ,although I am not sure that site is still there, that had all the info he needed. The only thing you have to decide on is what size rotor you use. I strongly encourage you to use no smaller than a 185. A 165 is all of 15 grams lighter and that weight is nothing at all to have the extra power of a 185. I am moving to a 203 mm rotor on the new bike. I just sent the money today for it as a matter of fact.

    And just to clear a few things up my bike isn't broken or anything like that. I still ride it all the time but it has 24 inch wheels and no front brake. I am also getting a custom fork made for my new custom frame that uses post mount. Its a far superior mounting method and it also eliminates a couple grams of adaptor and it is one less thing to break.

    If you need any help with figuring out the math end of it or whatever just pm me or post here or email me at [email protected] and I'll get you Paul's email address. Since doing my first one he has done a few more so I'm sure he's a pro with it.
     
  8. Bloodhound

    Bloodhound Steffen L.T.

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    could we see a pic of this 'post mounting' system? I dont really get what it is.
     
  9. BrettM

    BrettM New Member

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    Here is that info from the Avid site.

    Disc Brake Specs

    Hub Specifications
    Front hub offset - 10.16 mm
    Rear hub offset - 15.00 mm
    Bolt hole circle - 44 mm
    6 Bolts




    Rotor Size
    Front diameter - 165 mm
    Rear diameter - 165 mm
    Thickness - 1.8 mm
    Pad Clearance - .6 - .8 mm



    Fork Mount
    Mechanical Post Style - 74 mm standard
    International - Yes, with mounting bracket

    Rear Mount
    Mechanical International - Yes, with mounting bracket
    Perpendicular Style - No [Perpendicular = Hayes = 22 mm
    International = Parallel = 51 mm]
     
  10. xxxfr

    xxxfr RCP FABRICATION

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    brett...u got 24's on the peyto......got any updated pics?
     
  11. BrettM

    BrettM New Member

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    I stole a fun bolt off the rear king for my trials bike and a bb cup for my bmx so she isn't too picture worthy at the moment. I'll get you one soon.
     
  12. durkie

    durkie Member

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    does anyone know the status of this kind of rear mount? http://www.biketrials.com/VIP/ThibautMarriaux/index.shtml

    that's an old old page about tibo, and his rear disc mount looks really cool, kind of an IS version of brett's peyto mounts. does anyone know the status of it, like if it ever worked? i could easily see it being an idea that fell through the cracks, since diamondback doesn't seem to be doing too much with trials recently.
     
  13. tomacropod

    tomacropod Rum Pig

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    that's not a standard discmount obviously, custom made to fit the louise caliper. Kind of like the brisa b26d? it is better at distributing the braking forces, less likely to break the mount than a purely top mounted seatstay mount.

    I imagine it probably worked quite well. You don't need to do fancy things like that to get an IS disc mount that works though, look at the megamo stocks. A simple brace connecting the seat and chainstays - and I've never heard of any of them braking.

    The main problem with disc mounts in trials is that in order to make one that works, you have to move away from the "cookie cutter" dropouts that most manufacturers get out of a catalogue, and which are pretty much designed for either XC hardtails or jumping/street bikes, neither of which need anything special to cope with braking forces. This raises the cost, and is therefore undesirable.

    - Joel
     
  14. BrettM

    BrettM New Member

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    Yes mounts inbetween the stays work very well. I decided I had to be original and use post mount tho. Actually it is because it is a better style and it eliminates an adaptor.

    Brisa put the idea into production and even tried to patent it like they were the first people to ever think of it. Brisa kinda messed the design of it up by adding that brace in there. It does aboots as much bracing as a head tube gusset does with a rear disk mounted that way. Just extra weight. Other than that I used the Brisa full disk for a while and no problems. On any other frame with regular mounts the longest they have lasted are a month and a half. The only things they messed up were the brace and believing that a xc brake would be ok to use even tho trials uses more force than a dh bike would. A 160 rotor just won't cut it.