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  1. #1
    fight the system
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    Custom DH rebuild - Unibomber

    In 2000 / 2001 I built a few DH frames but a year afterwards I had so much else going on I hardly rode em. After moving to Colorado recently and hitting up Keystone a few times this year the addiction is back and it was clear I needed to do some upgrading. It took a bit to get back in the loop but with some of your help and a few bucks I rebuilt my 9lbs cromo Unibomber frame (200-220mm adjustable travel) into on sweet machine.

    The changes: Was - Now
    Fork: White bros UD180 - Boxxer World Cup
    Stem: generic Ė Sunline DM
    Bar: Titec Hellbent Ė Easton EA70
    Brakes: XT 160mm Ė Code 203/180
    Shifters: Deore 8spd Ė X9 8spd
    Derailleur: cheap road Ė X9
    Cassette: XT 8spd Ė XT 9spd
    Pedals: Odyssey Twisted Ė Atomlab Trailking
    Tires: Nokian Gazzaloddi / Irc Ė Maxxis Minon 2.5Ē DHF
    Tubes: yes Ė Ghetto stans with weather stripping for hand pump inflation

    I gave it my first test this weekend on a Moab trip hitting up the Porc Rim, Moab Rim, Amasaback and the Portal Trail. First I gotta say my 5.10 shoes are great not only for riding but the super sticky rubber is great for hiking my 40 pound beast up the Portal, which by the way, is one great trail for a bike like this.

    The best upgrade has to be the tires. Iím running 2.5 Minions set up with ghetto stans. These tires blow everything else Iíve ever run away. The grip is awesome, it breaks loose predictably, drifts great in corners and rolls fast. I owned dozens of DH tires a half a dozen years ago but nothing came close to how good these are. Best money spent.

    Boxxer World Cup is great but honestly my UD180 was a really good fork but it was way past its prime. Iím still dialing in the adjustments on the Boxxer but it I think I was having more trouble on my early morning rides when it was 15F out.

    Everything else kicks ass as it should. I was hoping to stick with 8spd but itís so hard to find I gave up and went with 9. The bonus is with the sram shifters I can put them on the grip side of the brake lever. I run my brake levers in so far shimano shifters end up a mile away from my hands. The ergonomics are way better.

    I cant wait to spend a day with a chair lift to get some real time on this thing. Pedaling up trails is still worth it but there is a lot less filler and more killer on a ski hill!

    Here are the pics.
    Attached Images Attached Images
    If you believe that I've got some magic beans to sell ya.

  2. #2
    Glad to Be Alive
    Reputation: SHIVER ME TIMBERS's Avatar
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    nice to see that bike back out......congrats
    the trick is ENJOYING YOUR LIFE EACH DAY, don't waste them away wishing for better days

  3. #3
    "Its All Good"
    Reputation: Whafe's Avatar
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    now that has to be a buzz, riding a steed where by you made the frame, the ducks nuts really.... Awesome thread....
    The_Lecht_Rocks: whafe - cheeers - may i offer an official apology for the wagon wheeler "dis-belief"

  4. #4
    moaaar shimz
    Reputation: tacubaya's Avatar
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    doooooooooooooope

    you should attach a floater to that rig!

    congrats, looks awesome

  5. #5
    Is flexy
    Reputation: njhcx4xlife's Avatar
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    That thing is sick. One of the nicest homebuilt rigs I've seen.
    Good People... www.efingersports.com

  6. #6
    freeride jerk
    Reputation: Tj Pope's Avatar
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    thats pretty awesome man!! keep up the good work.
    [SIZE="5"]SHANTY[/SIZE]

  7. #7
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    Quote Originally Posted by tacubaya
    doooooooooooooope

    you should attach a floater to that rig!

    congrats, looks awesome
    Naw, less is more. This frame was build to be light and simple not sophisticated. I tried building a better mouse trap in another design and while it worked very well I couldn't get the frame under the 10 lbs barrier. That year Nico won worlds on his V process and Greg won the world cup on an orange, both bikes lacked a floater and ran on just a single pivot. They are the fastest guys out there running the simplest bikes. I figure might as well take a stab at that mentality and was rather surprised just how well it ended up working going up and down. Maybe a floater would improve braking slightly but I donít think the drawbacks of weight, rattling and more things to go wrong are worth it unless itís actually part of the linkage that drives the shock. Just my $.02
    If you believe that I've got some magic beans to sell ya.

  8. #8
    clyde in training
    Reputation: 08nwsula's Avatar
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    preforms better now and looks a lot better. good job

  9. #9
    Equal opportunity meanie
    Reputation: DHidiot's Avatar
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    Nice!

    What made you choose the pivot point that you did?

    I think that could benefit a lot from a more updated shock that has more bottom out resistance. Otherwise looks sharp as hell.
    805

  10. #10
    Meh.
    Reputation: XSL_WiLL's Avatar
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    Nice. Do you still have those XT 4pots?

  11. #11
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    Quote Originally Posted by XSL_WiLL
    Nice. Do you still have those XT 4pots?
    ya, you intersted in giving them a new home?
    If you believe that I've got some magic beans to sell ya.

  12. #12
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    Quote Originally Posted by DHidiot
    Nice!

    What made you choose the pivot point that you did?

    I think that could benefit a lot from a more updated shock that has more bottom out resistance. Otherwise looks sharp as hell.
    Pivot placement - wanted the biggest falling rate chain growth possible with efficient pedaling. Depending on chain ring size around a 12% growth rate / wheel travel yields the most efficient pedaling balancing the downward thrust of a pedal stroke with the upward force of the chain tension (without getting into more engineering mumbo jumbo). The key of my thinking is you rarely pedal any other time other than the sag point and I doubt anyone will be trying to pedal when the suspension is bottomed out. At the end of the travel chain growth just causes problems with the drive train by tugging on the chain and derailleur but with my design near the end of the travel the growth drops to zero like a concentric pivot design. I still end up with a back and up trajectory for absorbing square hits, and as a bonus the back end is much shorter than something like a Foes making it a lot stiffer. If you map out the maestro or a DW link suspension youíll see they average to a spot similar to what I have but keep in mind my bike was built in 2000, a few years before either of those came out.

    The shock Ė ya Iím with you on this. Itís a little over driven too as it only has 2.75Ē stroke. I have plans to build another Unibomber with a modern 3.0Ē shock but I dont see the point in a pedaling platform. I think you'd be supprised how it pedals without one.

    Iím also planning to change the BB shell to fit XT bb bearings directly like the new Trek Madone and Scott road frames (I think yetiís are like this now too). Its currently machined to pressfit profile bearings like the MID design on a bmx. I might even weld the seat right to the seat tube since it doesnít matter too much where it is eliminating the seat post and cutting out more weight. Eventually I think I can get the bike a few pounds under 40 without making it fragile.
    If you believe that I've got some magic beans to sell ya.

  13. #13
    Equal opportunity meanie
    Reputation: DHidiot's Avatar
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    I like what you're thinking with the pivot point. FSR's/DW's/VPP's all map out to average around the same location (migratory for DW/VPP), but just a tad bit foward and maybe lower depending on the chainring size. It just seemed like the location of yours was a bit exaggerated out and back.

    Why falling rate though? They're better for square edges but any big staircase type things or hits/g-outs are just murder for falling rate designs. That's why I suggested a more progressive shock if you weren't to use any sort of linkage to control the leverage curve, not necessary updated for need of a platform. Any idea what the leverage curve is on it? Starting leverage? Ending? Upwards or downwards opening curve? Pinnacles? Inflection points? My guess is that it would be linearly increasing a la Bullet, but I could be wrong.
    805

  14. #14
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    Quote Originally Posted by DHidiot
    I like what you're thinking with the pivot point. FSR's/DW's/VPP's all map out to average around the same location (migratory for DW/VPP), but just a tad bit foward and maybe lower depending on the chainring size. It just seemed like the location of yours was a bit exaggerated out and back.

    Why falling rate though? They're better for square edges but any big staircase type things or hits/g-outs are just murder for falling rate designs. That's why I suggested a more progressive shock if you weren't to use any sort of linkage to control the leverage curve, not necessary updated for need of a platform. Any idea what the leverage curve is on it? Starting leverage? Ending? Upwards or downwards opening curve? Pinnacles? Inflection points? My guess is that it would be linearly increasing a la Bullet, but I could be wrong.
    When i wrote falling rate i was talking about the chain growth rate not the shock rate. The shock rate is quite linear but adjustable to be slightly rising or falling through the 3 holes at the front and an eccentric connection on the rear triangle. I've settle on the rising side but its quite subtle and pretty much linear.

    The exaggeration of the pivot placement was intentional to really see how it would feel. It's so close to the wheel to maximize the falling chain growth and at the upper height limit to maximize the wheel path's backwards and up motion. I was really inspired by the Balfa BB7 at the time but saw too many chain problems taking it higher than a standard drivetrain would allow. Keep in mind that the pivot placement effecively lowers as it compresses because it is so reward.

    I sacrificed a little too much mud clearance on this one since i made it for smaller 26" or big 24" rear wheels. The next one will be a 5mm more forward have a slightly lower pivot too, about 5mm, just like you mentioned.
    If you believe that I've got some magic beans to sell ya.

  15. #15
    e.f.f.e.c.t smoothoperatr
    Reputation: themarsvolta55's Avatar
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    thats what i want to do! haha perfect thread

    lots of questions

    what kind of welding process?
    what kind of material and why?
    did u make urself a homemade jig?
    how did u create your frame? im fooling around using a 3-D CAD program
    i want to make a single pivot too, around the looks of a chumba wumba f4/5 w different shock placements

  16. #16
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    Quote Originally Posted by themarsvolta55
    thats what i want to do! haha perfect thread

    lots of questions

    what kind of welding process?
    what kind of material and why?
    did u make urself a homemade jig?
    how did u create your frame? im fooling around using a 3-D CAD program
    i want to make a single pivot too, around the looks of a chumba wumba f4/5 w different shock placements
    Just the facts:
    what kind of welding process? - Mig

    what kind of material and why? - 4130 aircraft cromo straight gauge Ė tough, cheap, no post heat treating. More interested in getting design right first then tackle the tubing.

    did u make urself a homemade jig? - home made jig. Spent more time making jig than bike.

    how did u create your frame? Ė I used Mechanical Desktop and mathcad. I'm using SolidEdge now, all 3D.
    If you believe that I've got some magic beans to sell ya.

  17. #17
    Meh.
    Reputation: XSL_WiLL's Avatar
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    Quote Originally Posted by jakomonster
    ya, you intersted in giving them a new home?
    Maybe. I've got one set, would consider another.

  18. #18
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    sick, thats awesome how you built it yourself and it preforms good, oh and looks sick too!

  19. #19
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    With that boxxxer and new paint it looks tits...

    Have you had a chance to race it yet?

  20. #20
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    Quote Originally Posted by assgrinder
    With that boxxxer and new paint it looks tits...

    Have you had a chance to race it yet?

    Thanks for the complements on the paint. Iím happy with it too although next time Iím getting it powder coated cause it scratches way too easy.

    Havenít raced it yet, Iíll have to wait prolly 6 more months before the season starts.
    If you believe that I've got some magic beans to sell ya.

  21. #21
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    Quote Originally Posted by jakomonster
    Thanks for the complements on the paint. Iím happy with it too although next time Iím getting it powder coated cause it scratches way too easy.

    Havenít raced it yet, Iíll have to wait prolly 6 more months before the season starts.
    what shock were you thinking about replacing the Fox with? Another
    DHX, Cane Creek, Roco? With a new shock that bike will look like sex.

    What did the build cost you?

  22. #22
    DenverDH'er
    Reputation: rep_1969's Avatar
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    Sweet.

  23. #23
    fight the system
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    Quote Originally Posted by assgrinder
    what shock were you thinking about replacing the Fox with? Another
    DHX, Cane Creek, Roco? With a new shock that bike will look like sex.

    What did the build cost you?
    I wont change the shock on this frame. I'm planning on building another frame soon designed around a 3" stroke shock. I have my eye on the new Vivid.

    The cost of making your own frame can be pretty low but the hours spent can get astronomical. I dumped some coin into the new parts, I think you have a good idea what it is all worth based on my upgrade list but I'd rather not say incase my wife sees the number
    If you believe that I've got some magic beans to sell ya.

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