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  1. #1
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    basement built gt fatbike!

    hello all, Ive been jealous along time of all you fat bike people..but no more! I recycled my old gt borrego frame. I cut most of the rear end off, extended the seat and chain stays with another frame and brazed them on, I made the seat and chain stay yokes out of the left over seat stays. I made a quick jig in the basement and reassembled the old girl. I bought some tires and rims and a fork and now I have my very own one of a king fatbike!
    these first pics were before paint and not quite finished welding yet, no disk brake tab.
    basement built gt fatbike!-sspx0627.jpg

    basement built gt fatbike!-sspx0628.jpg

    basement built gt fatbike!-sspx0629.jpg

    basement built gt fatbike!-sspx0632.jpg

    basement built gt fatbike!-sspx0633.jpg

  2. #2
    workin' it Administrator
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    NIce work! Sleeved the dropouts over the old ones? The BB widening is quite impressive I must say.

    Good on you to recycle so well!
    Try this: HTFU

  3. #3
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    here are some pics of the gt finished with new paint. and the chain, seat stays are sleeved it made the most sense to me at least.
    basement built gt fatbike!-img-20111112-00088.jpg

    basement built gt fatbike!-sdc13004.jpg

    basement built gt fatbike!-img-20111112-00091.jpg

    basement built gt fatbike!-sdc13005.jpg

    basement built gt fatbike!-sdc1300069.jpg

  4. #4
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    Cool. Nice job.

  5. #5
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    I love it!! Wonderful job. Now go ride the bejewbus out of it.

    Just curious, what's the idea behind the spokes?

  6. #6
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    Good ob on the BB shell. What spindle did you use?

  7. #7
    ride more
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    Wow, that's really cool.

  8. #8
    addicted to chunk
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    Cool project!
    Those spokes are craaaazy! I love it.
    Riding.....

  9. #9
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    Wow that's some serious work, great result! Congrats.
    Jason
    Disclaimer: www.paramountsports.net

  10. #10
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    I always prefer a home-brew

    How does it handle?

    (Added some rep to you)
    As little bike as possible, as silent as possible.
    Latitude: 57º36' Highlands, Scotland

  11. #11
    Geordie biker
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    Superb, love these self builds
    2014 milage so far - 2,167
    www.ukfatbikes.co.uk

  12. #12
    That Unicycle Guy
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    I can't quite make it out but is that 4 pairs of twisted spokes on the front with the rest strait?

    buy a pack of 50 spokes for the twisty pattern?

    whatever your reasons great job.

  13. #13
    A Surly Maverick
    Reputation: Dr Feelygood !'s Avatar
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    Great build, well done
    A Fatback'd Lefty for who life IS a Beach

  14. #14
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    I am similarly in the middle of a standard steel hardtale to fatbike conversion;
    BB widing???EXTENDING

    Good start you have, following Intended purely as constructive criticism -
    Looks like the new fat setup gave you around 67-68° of head tube angle (and even slacker seattube). Unless you get a fork with massive amount of rake, the fork trail is probably much too big (100+mm) and it will have some very wierd, querky steering. Keeping most of the original frames seatstays probably somewhat limited the needed changes you could make to the frame geometry. You probably should have increased the angle between the seattube and the chainstays by a few degrees (reducing the BB drop) so that the head tube angles would remain a bit steeper and keep fork trail <90mm.

    Hard to tell from the pictures but is there some crimping of the seatstays where you added clearance bend? My attempt to bend CS and SS in-place were a complete failure, convinced me to just cut them off entirely and start fresh. New steel 29er chainstays and seatstays long enough for a fatbike only cost me about $50 total from NOVA. Much easier to get them bent to shape beforehand and then attach to the frame, no sleeve extensions needed.

    Interesting idea on widening the existing bottom bracket shell. What method of welding (does not llook like brazing) and what did you use as a jig for this to keep the lengthened shell strait?

  15. #15
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    Awesome. The triple triangle/fattie combo works very well!
    Look out honey, 'cause I'm usin' technology

  16. #16
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    Twisty spokes! Love it!

  17. #17
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    Quote Originally Posted by GrayJay View Post
    I am similarly in the middle of a standard steel hardtale to fatbike conversion;

    Good start you have, following Intended purely as constructive criticism -
    Looks like the new fat setup gave you around 67-68° of head tube angle (and even slacker seattube). Unless you get a fork with massive amount of rake, the fork trail is probably much too big (100+mm) and it will have some very wierd, querky steering. Keeping most of the original frames seatstays probably somewhat limited the needed changes you could make to the frame geometry. You probably should have increased the angle between the seattube and the chainstays by a few degrees (reducing the BB drop) so that the head tube angles would remain a bit steeper and keep fork trail <90mm.

    Hard to tell from the pictures but is there some crimping of the seatstays where you added clearance bend? My attempt to bend CS and SS in-place were a complete failure, convinced me to just cut them off entirely and start fresh. New steel 29er chainstays and seatstays long enough for a fatbike only cost me about $50 total from NOVA. Much easier to get them bent to shape beforehand and then attach to the frame, no sleeve extensions needed.

    Interesting idea on widening the existing bottom bracket shell. What method of welding (does not llook like brazing) and what did you use as a jig for this to keep the lengthened shell strait?
    grayjay good eye on the the head tube angle! unfortunately, dislexia kicked in and I reversed fork length numbers from 447 to 474. so now my bike rides like a dh bike with long travel its alittle sluggish on hill climbs and I have to man handle it a bit in some corners, but over all the bike rides awesome. I have well over 700km's on it.

    When I did the b.b. I cut off pieces of another b.b. I then used an old steel b.b. cup and threade the two together. The drive side was a bit of a pain, because of the fixed cup lip you can't thread it thru to the other side, so I had to grind down a b.b. tool to fit thru the bb shell and used a non drive side cup and threaded it backwards.

    almost all of the welding was done with a 110 flux core welder. I did braze the seat and chainstays together I had to extend them. My next build Iam going to buy two 29er frame sets from henry james, one for me one for thew wife.(she doesnt know yet she hates bikes)

    the crimping on the seat stays I think youre refering to the bends ridght above the tire, if so I tacked a piece of steel (5.5" wide gives me lots of tire clearance) between the stays and pulled them back together. I did have to put some clearance dents in the chainstays so the cranks wouldnt hit all is good now.

    I hope I answered your questions. sorry for the run on.

  18. #18
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    Quote Originally Posted by ericpulvermacher View Post
    I can't quite make it out but is that 4 pairs of twisted spokes on the front with the rest strait?

    buy a pack of 50 spokes for the twisty pattern?

    whatever your reasons great job.
    Im a bit on the cheap side I try to recycle all of my old parts. The rear spokes were to long I thought I had the right length, they were not so I twisted them. The front similar issue I only had enough to do partial build with either colour, so yes there is a twisty cross in the front. The front is being rebuil I found the rest of my black spokes.

  19. #19
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    Wow, that’s some serious backyard engineering going on there. Really now, your home-fatty ROCKS!!! I wish I had a welder… and a die grinder…*and a lathe… and a CNC machine…
    QUOTE from MTBR.COM: You have given Brewtality too much Reputation in the last 24 hours, try again later.

  20. #20
    That Unicycle Guy
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    Quote Originally Posted by angryx View Post
    Im a bit on the cheap side I try to recycle all of my old parts. The rear spokes were to long I thought I had the right length, they were not so I twisted them. The front similar issue I only had enough to do partial build with either colour, so yes there is a twisty cross in the front. The front is being rebuil I found the rest of my black spokes.
    Cool, I have also used some "creative" spoke patterns in the past to re-use spokes. I can understand why you are re-building the front but the twisty cross does look really cool.

  21. #21
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    Quote Originally Posted by Leopold Porkstacker View Post
    Wow, that’s some serious backyard engineering going on there. Really now, your home-fatty ROCKS!!! I wish I had a welder… and a die grinder…*and a lathe… and a CNC machine…
    thanks Leopold Porkstacker, only specialty tool was the welder, everything else was done with a 4.5" angle grinder. needless to say all of those tools what be great to have.

  22. #22
    will rant for food
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    Quote Originally Posted by angryx View Post
    thanks Leopold Porkstacker, only specialty tool was the welder, everything else was done with a 4.5" angle grinder.
    I admire resourceful people, good job
    Latitude: 44.93 N

  23. #23
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    Thanks drewdiller, Ive always made do with what I have, it doesnt help that I'm impatient and want things done asap

  24. #24
    will rant for food
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    Quote Originally Posted by angryx View Post
    Thanks drewdiller, Ive always made do with what I have, it doesnt help that I'm impatient and want things done asap
    Oh I don't know. I told myself I was going to slow down on my next frame build, and I slowed down too much. Work how you work best.
    Latitude: 44.93 N

  25. #25
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    That is awesome. Next step "leaking" photos to show GT is releasing a fatbike to make everybody freak out.

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