GT1 frame with lots of extra steel

Discussion in 'Motorized Bicycle Welding, Fabrication and Paintin' started by soup325, Feb 8, 2013.

  1. soup325

    soup325 New Member

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    thanks,

    I have done about 4 hours riding on the bike so far. there is a big difference in how the old bike was, and what it now.

    single speed vs 8spd now.

    there is noticeable change in weight. it is heavier (naturally) and the center of gravity has moved back.

    I wish I had made the frame longer, as I am 6ft 6. part of the reason for the layback seat post, was to accommodate a more comfortable riding position. as the build has taken about 2 years to complete.

    one of the biggest problems, I have had was the chinese parts not mix with japanese or western made components.

    using the GT1 frame, it came with double walled rim wheels, these rims and spokes are not the same, so I binned the lot and went for some downhill rims with 14g DT champion spokes and nipples.


    The Gussets

    I think I have achieved, what I set out to do. reduce the vibrations from the engine and increase the strength of the frame. the GT1 frame is already a stronger frame than the standard bike frame. with 1.8mm steel tubing, the theory was to change the resonance frequency of the engine. By adding gussets to the frame corners, I didn't want to have the frame crack, plus the added bonus of making the frame vibrate less.

    The bike, I felt shook like Christchurch did 2011. After about 30min riding, I felt like I had been on one of those vibra plate things you find in gyms. The gussets have made this a thing of the past, where most other people focus on balancing the crank.

    I would like to think if I balanced the crank as well, I would have a very smooth ride for a chinagirl.

    The Tank

    The inspiration for the tank came from here. I cant remember who it was but someone posted their tank on here on a interesting looking wooden frame.

    I get a bit of flak for the airworthiness and engineering branch at work (I work in the flight operations and licensing) over the crash worthiness of the tank. But hopefully I can get some sloshing compound to coat the inside of the tank in a rubber coating.
     
  2. truckd

    truckd Active Member

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    I got one word WOW!
     
  3. soup325

    soup325 New Member

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    Re: GT1 frame with lots of extra steel - update

    well here it is, sort of. Still a bit of work to do, including mudguards and homebuilt Jag CDI

    [​IMG]

    [​IMG]

    Got about 4 hours of ride time in so far, chain stretch is chronic
     
  4. soup325

    soup325 New Member

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    [​IMG]

    I have been working on lengthening the mudguards. the one above is the front. I ordered two sets, so I could have super long guards. Not really necessary, but I like to look. I have used rivets and liquid nails to join the two sections together.

    To have a long rear guard is a bit of a problem. Because these guards are designed to be attached to the axle, they come off when the wheel is removed.

    I am working on brackets for the front half of the rear guard. So these can be fixed to the bike frame and produce less rattle. the rear half is designed to come off with the wheel. Otherwise I will need to cut the guards off to remove the wheel. as the guards are made of metal.

    I will post at a later date.

    [​IMG]


    Above, I have installed the SBP chain guard from the kit onto the clutch housing.
    I have lowered the 'screw-on 2nd part of the cover' to cover the smaller gear, in a different way.
     
    #24 soup325, May 11, 2013
    Last edited: May 11, 2013
  5. soup325

    soup325 New Member

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    [​IMG]

    A better pic of the longer mud guard on the front

    [​IMG]

    plus, I have removed stickers from the forks to lower the air resistance by 0.0000000000003 and increase HP.

    also added is the new home built CDI and CR80 coil.
     
  6. killercanuck

    killercanuck New Member

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    Any HP is good HP :p Looking good. Fear no puddle!
     
  7. dodge dude94

    dodge dude94 New Member

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    Looks good.

    But quick question...are you seriously THAT tall?

    Damn. lol
     
  8. soup325

    soup325 New Member

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    Once that rear guard is on, no puddle is safe.


    Umm, Im like 6 foot 6. I am kicking myself that I did not lengthen the frame for more of a comfortable ride. lol
     
  9. soup325

    soup325 New Member

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    the motor is a 48cc.

    at $220 for the motor kit (single speed set up) it one of the cheapest part of the bike. from mbbimports.com.au

    and $500 for the Gt-1 frame

    the sick bike parts shift kit + shipping to Australia comes to $300

    the steel gussets and exhaust pipe (just the welding) cost around $500
    this was done at mates rates by a certified structural engineer.

    the IGH 8 speed nexus + new front and rear wheel + spokes + balancing

    came in at around the $500 mark

    the bike will have about a 280 day payback period. based on $9/day carparking at my work.

    It has taking me about 2 years to get this far.

    I have a seagull outboard motor brass tank on the way. the current mini-keg is too bulky.
    which is dumb, as I really like, its just impractical.

    I cant wait to show this off at a 'Mens Shed' http://www.mensshed.org/home/.aspx

    Even thou Im only 30. Im sure the guys at the shed would love it.
     
  10. Robby

    Robby New Member

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    Your buddy has done some nice Tig welds! On the roll cages we fabricate at work for race cars we do what you did on the rear dropout gusset: the gap at the end in the corner can help reduce concentrating weld tension from shrinkage. If there is multiple planes of weld, like in corners, by leaving a little gap on the gusset corner (particularly if it's a wrap around gusset), when one weld cools, it's less likely to form a crack in the corner! Maybe good accidental engineering?!
    Top work.
     
  11. Jeckler

    Jeckler New Member

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    Are you using all 4 eyes on the rear stay for the carrier? And you have both cantilever and disc brakes on that?
     
  12. soup325

    soup325 New Member

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    Thanks.. the rear gusset corners, weren't accidental but, lazy engineering. I could not be bothered to grind down the steel to fit nicely into the corners. I was more, if I make a space in the corner, I dont have to spend more time fabing up the corner to fit.
     
    #32 soup325, Jul 10, 2013
    Last edited: Jul 10, 2013
  13. soup325

    soup325 New Member

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    No, I'm only using the 2 eyes. for the bike rack and mud guard stays.

    I have the 4 eyes on there as it was on the donor bike, I got it from.

    I not sure how much you know about internal gear hubs. but I have the 'nexus' SG-8R38 IGH, plus roller brake (which is what you see). the disc you see is a heat sink. coz that brake gets really hot. The alfine SG-S501 is the disk brake version. only comes in black. both gear hubs have the same internals. the only difference is the disc brake or roller brake and colour.

    http://sheldonbrown.com/nexus8.shtml
     
  14. Jeckler

    Jeckler New Member

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    Interesting. Probably stops pretty quick.
    I'm sure you thought of this, but maybe modify the rear guard to use the extra eyelets for mounting.
     
  15. soup325

    soup325 New Member

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    I was thinking of using the two eyelets. However, the upper most set of eyes are too far forward for my styling. Plus the length of the stays are perfect length for the lower set.

    I am modifying a seagull outboard motor brass tank as a replacement tank. a lot less bulk.

    here is a video of an example of what the tank looks like.
    http://www.youtube.com/watch?feature=player_detailpage&v=-adwm9K77pY
     
  16. soup325

    soup325 New Member

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    Well time for some updated pics.

    New exhaust, scooter style. Seagull gas tank. AN fuel fittings. engine mods, lockwiring. schwalbe ebike tyres.
    [​IMG][/URL]

    [​IMG][/URL]

    ENGINE MODS!!!!! Dellorto sha, reed valve, skf bearings, ported jug, ceramic piston, hi-comp head, iridium spark plug, MSD boot and 8mm HT wire.
    [​IMG][/URL]

    Lockwiring, Not the only place just one of many.
    [​IMG][/URL]
     

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