Gravity racer - Calling all daredevils!

Discussion in 'BUILD CHALLENGES' started by breakurnees, Jun 17, 2011.

  1. breakurnees

    breakurnees

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    It is a straight springer fork, but I flipped the bracket it is on to rake it further. I think just putting a standard fork on will help. Righting the frame would be a pain at this point, and the wheelbase would become a lot shorter. I'll give that fork a ride first, and then try righting it if it is still twitchy.
     
  2. fast eddie

    fast eddie

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    ya got bigger brass than i, ya couldnt pay me enough to ride a flipped frame again, i raced on one in a world cup event and it scared the bageezus outta me! springer forks are taller so they increase rake, a flipped frame increases rake, flipped brackets increase racke, but .. the best set up is to leave the head tube angle where it is. a few inches of wheelbase is not worth the dramatic loss of maneuverability your experiencing with your set up. ride safe brother
    fast eddie
     
  3. OUTLAW

    OUTLAW

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    hey Eddie, these guys are funny. hope we don't hear about em how they died. wow, flipped bikes, springers, yep, they got bigger brass then me too. I guess if they are going around 30 they can get away with it. but over 60, too scary for me. when I built mine I went 68 on it. no prob. but it was set up right. of course I had good mentors like you and alot of others who new how to build em an ride em. sooo, this ought to be interesting.
    take care my friend.


    Outlaw :?:
     
  4. fast eddie

    fast eddie

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    good to hear from ya outlaw and thanx for the kind words. i didnt get to do any riding this summer, alot of baby mama drama to deal w/, but im ready for next summer with a new bike and a new streetluge ! trial and error is a good way to learn, hopefully no serious crashes happen, building/rebuilding/tweeking/tryin new setups .... that's all part of the fun! ive ridden some wrecks down the hills thinking i had a brilliant idea, i would trade those lessons for anything. notice i dont post pix of any of those wrecks .. only the good bikes!

    fast eddie
     
  5. OUTLAW

    OUTLAW

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    yep, your right. but even posting the bad is good to learn from. I went back thru all the builds and there is some good ideas, some work some don't. I was lucky to get it done right the first time. over on gravity bike's there was alot of good builders with lots of good advice. that helps alot when your running down a road over 40 mph. putting on the right gear is a + to keep ya half safe. lucky I had no problems. I don't build em anymore. just no time and I too have to go a distance for the good runs even here in the PNW.lol.I torn the bike down an rebuilt it back to a BMX and gave it to a deserving kid here in my hood. all you daredevils, stay safe. good runnin on the hills, it's a blast. :)

    Outlaw 8)
     
  6. cobraontrike

    cobraontrike

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    Has anyone heard of the crested butte chainless race. I have done it the last two years and I've seen gravity bikes compete. The race is so much fun. The only rule is no pedaling. U can have a chain if u have a coaster brake but it has to be tied to the sprocket so u can't pedal. I did it on my trike two years ago and a tall bike this year
     
  7. fast eddie

    fast eddie

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    ive wanted to that race for years, never seems to work out for me, is it a dirt road or paved?
     
  8. subadrew

    subadrew

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    all paved except for the last 200 yards(ish) which is kinda sketchy =)
     
  9. TXBONE

    TXBONE

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    you have to look up gravity racing tuna canyon california. Its an unbelieveably steep road here in topanga canyon ca. Its called TUNA CANYON ROAD. The road borders topanga canyon and malibu dropping down the hole mountain at an insane grade. People come from all over and i see them all the time as i drive home to TOPANGA.They hold soap box races and gravity bike races illegally here. They turned it into a 1 way road about 5 years ago, which makes it ideaI for gravity racing bikes and crazy skateboarders too. Get going 62 MPH on my downhill bike, kinda lame in the street, but if i had a gravity bike, id bet i could get it going 70 mph plus.
     
  10. S.I.N. CYCLES

    S.I.N. CYCLES

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    breakurnees -
    One thing for sure springer fork is probably not well suited for speed. You should really just try swapping the fork to a BMX fork something with a 30mm offset will give you a silly stable ride, like hands behind your back in the straights. Although you will have a bit of wheel "flop" when you steer with the fork to much. I think you will be happy with the results. Flipped frames are all about body language, which scares a lot of folks. You could always move towards a 0 offset fork (flatland bmx fork) for tighter steering. S.I.N Brothers have went through multiple forks from wrecking our consensus is to use the beefiest forks you can get a hold of! I have ridden flipped, not flipped, and of course our hybrids that combine a bit of both. They all just take getting used to, and sometimes run better on different types of roads.

    Kneelers are great, but you can not solely depend on them, having sturdy rear pegs is super important. Being able to shift your weight between handlebars, knees, and pegs is absolutely key to getting the most out of any road. We have found seats to be near pointless except for causing serious damage to anything between your legs guy or gal.

    Keep riding!
     
  11. breakurnees

    breakurnees

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    Thanks SIN. What is a good headtube angle? Since I stretched the bike at the pivot, I can decrease rake by raising the bike up.
     
  12. fast eddie

    fast eddie

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    im with SIN, there is no need for seats, a sawed the seat tube fluch with the top tubes, filled it in, and the rear fender makes sure i dont get by butt on the on the back wheel. i have a 20" fully spring bike that i will take the rear swing arm off of, and im gona try mounting it to the front triangle off of a fully sprung 26" bike. i wont use the spring but i will use an adjustable metal peice that will keep the frame rigid while allowing me to adjust head tube angle by lengthening/shortening that rod. if someone beats me to this let me know what you learn. guys always stretch the fronts of bikes but i think thats wrong, the front triangle on a bmx is fine, stretch the back and you'll get yer weight closer centered between the wheels instead of riding over the back wheel with less weight - and therefore less control - over the front wheel.

    fast eddie
     
  13. Philphine

    Philphine

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    if you were gonna stretch the back, wouldn't you be trying the 26" swingarm on the 20" frame?

    with the actual build off over, does this thread keep going? like become more general g-bike discussion than build off? i was gonna experiment a little more (mostly just switch wheels and tires), but i figured i'd just post the rest in a regular thread or most likely just continue my parallel thread on freakbike.
     
  14. fast eddie

    fast eddie

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    yea philpine yer right, i had that backward. have you tried anything like that? as for tires i think that usuing high pressure tires work great, theyre smooth and give less roll resistance. i used odyssys 110 psi for a long time, still do on one of my bikes, i aired 'em up to 90 psi to leave room for expansion from heat from rim braking
    fast eddie
     
  15. Philphine

    Philphine

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    i haven't tried it for anything like a g-bike. i have on a couple of other oddities. as long as the pivots are the same it's not too hard to do.

    yeah, my only try was with some tires that had a 40lb max inflation. i think now with cold weather coming i may take a tire off another bike and use it for at least one more try on the same hill i used before. the other bike is more important to me (one of my stretch cruisers using higher pressure tires), but i'm meaning to take it apart anyway over the winter so i can use the tire and hopefully get another before next spring, or just put it back when i have the other bike ready again.

    so at least one more try on the same hill with some straiter rims and the better tires, if i can make myself work out the details before it gets much colder. i mean to keep the bike though as a side project, so if not now, next spring.
     
  16. Beau

    Beau

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    I have built a bunch of these. I modify Mixte frames. run 20" forks off youth bike that have canti studs. High pressure BMX tires. The 130 pound tires. Hack the top section of the seat tube out. Bend the rear seat stays back and mount a bananna seat. Long and low.

    I turned mine into a drag bike. But you get the idea. It had bmx bars upside down.

    [​IMG]
     
  17. poverty with a view

    poverty with a view

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    Just be careful of metal rims and breaking/stopping. It will pop the tubes. Back in the day 25 years ago plus, we used tuff rims or mags. It kept the tubes from popping cause of the heat from the breaks. We rode in San Jose, Californiam down Quimby road and Sierra rd.. We were clocked at 72mph. We road a 20" in the rear with a 16" up front. We didn't like the extra weights. It made braking almost impossible. We made farings out of card board and fiberglass. You came with a bike with no fairing you got smoked,bad! :D

    I really dig what everyone has done with their bikes. It has inspired me to build one again. I live at 6200 ft, mountains and gnarly roads everywhere. Thanks everyone for the isperation! I

    PS
    if you do flip the frames you have to be mindful of the head tube angle. I didn't care for much rake at all, so most frames worked for us. We would put steering dampeners from a screen door on our handle bars.
    Pedal on my friends or should I say coast on my friends.
    Blue 8)
     
  18. fast eddie

    fast eddie

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    whos is this that posted last?
     
  19. poverty with a view

    poverty with a view

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  20. poverty with a view

    poverty with a view

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    I have to say I'm stoked about this thread. It has been a very long time since I rode a GB or even thought of one. I have been building custom bicycles now for a few years and now I see I have a new project in the future. I hit up my old friend that used to ride with me back in the day for some pictures of our old bikes. He is looking. Living in Tahoe with all the long windy roads here is going to make for a great winter project for some awesome summer riding. I think I have a friend here convinced to make his own bike too. Please keep in touch. Fast Eddie I tried to friend you on Facebook but it won't let me cause they think I am spam. I will send you a message on there if you could accept my friendship that would be great to get some inspiration from all the great bikes you have on that site. keep in touch. Blue 8)
     

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