Gravity racer - Calling all daredevils!

[breakurnees]

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.

[fast eddie]

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

[Philphine]

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.

[fast eddie]

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

[Philphine]

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.

[Beau]

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.

[poverty with a view]

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!

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

[fast eddie]

whos is this that posted last?

[poverty with a view]

Me Why?

[poverty with a view]

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

[fast eddie]

good to hear yer gonna build one, i thought maybe you were one of the 'old timers' that used to post on the gravitybike.com site. i didnt get to ride this summer, i even finished a new bike and aint got it up to speed yet, but ill remedy that next summer for sure! lookin forward to seen yer build!
fast eddie

[poverty with a view]

Not me. There was another guy that my friends and I rode with a few times from San Jose too. He was kinda known in The GB scene. Gonzo or some thing like that, i'm not a 100% on that. I can't remember. We all have drama in our life's. It will pass and you will be riding again. keep your head up and stay strong.I went threw the same thing a few years ago. Now I can't stop building.

[fast eddie]

i build bicycles too, thats a fun hobby, im putting a bicycle motor kit on one of them, should be fun! just wish i had more time for it all,

[Philphine]

here is where i stopped at for now. it's been like this for a month or two, but i meant to add another speed result when i posted it



the front wheel is a spin carbon mag i got off ebay. the rear wheel has a small crack so the set went cheap. the tire is a kenda rated at 100psi. i found out later though it's not good to try and get a spin up that high, to max out around 80psi. still should be better than before though. one good thing, someone on another forum has mentioned making a disc brake adapter for a spin, so if i got more serious or just have the extra cash if/when he does it, i can put on better brakes.

the rear is a wheel from an x-games bike. the bike i got the swing arm from for the other g-bike i made (the poseur). it came with a disc brake so no adapter needed. i can have front and rear discs maybe. the tire is a hoffman rated at over 100psi. the wheel disc were part of some close out off ebay. i got a couple sets together for not too much.

one problem i gave myself is i didn't want to mess with the spin rim trying to get my speedo sensor on it, so i tried to extend the leads to reach the rear wheel and messed up somehow. the speedo doesn't work. that's why i never got another time. maybe by next spring i can fix or replace it.

at first, even though i wasn't seriously thinking of starting g-bike competitions, i still tried to follow the rules that were posted fron that competition web site, but since they're not around any more, i may look for one of those pocketbike fairings. i like how that was done.

so that's mine for now. i don't know what more might happen with it, but i plan to keep it for now. maybe next spring i'll play with it more.

[fast eddie]

wow you got alot of work in that! it looks killer, good job. id like to put a fairing on my bike at some point, ive never done any fiberglass work but it's a time issue as always, im also one of those who has a garage ful of unfinished projects so im trying to concentrate on getting them done and NOT bringing in any new projects!
fast eddie