built thread: gx35 full suspension w/ 18 speeds (inframe too!)

[unknownbmxa88]

so im new, been lurking for a while, got some good ideas, and i have a couple simple to more complex builds including the 2 putter china garbage kits and a diy 4 stoke mount for the rear axel of my rat bicycle.

for my current build, i have a 2005 rockymountain element in large. its huge! has a 21' frame or something. but its exaclty what i need for this build.
has disc brakes and 22-36-44 front, 11-36 rear w/ 9 speed cassette. (YES NINE!) craigslist 300$, was over 1000$ 5 new, shows some wear cosmeticly but its 95% only having a slight hop in the rea wheel

for power, i have a honda gx35 that i got on craigslist for 50$ cash. yes thats right it was on a mosquito fogger, i didnt care i just saw "honda 4 stroke powered" and "used twice" so i had to buy a 76mm clutch and bolts for it. NBD. also bought a pocket bike air intake, and i am going to fab a custom straight pipe with a miffler on the end, not quite sure yet.

i choose to use a 5:1 pocket bike transmission from ebay. 12 tooth 410 sprocket to a 48t SBP sprocket.

i found this interesting post on another forum about a "tetra drive"

http://motorizedbikeforum.the-talk....r-sickbikeparts-sick-bike-parts-sbp-shift-kit

he uses 4 sprockets on the front cranks, 3 for gears and 1 for power. i plan on trying to copy this with 2 in the front and 1 for power. (outermost)
22-36 to 11-36.
for the rear shifter i plan to do the old grip shifter, and for the front, i plan to have a old style lever to engage what i call my "crawler gears". i hope to creat a sort of low range simular to when you put your jeep into 4 low to offroad or low range for pullng trailers.
so i will have 18 gears, not that i need that many
this is the engine, i only have a pic of it on my rat bike ATM

free image hosting




sorry the pictures suck so much, my phone is old.

 

[Dan]

Really awesome work UnknownBMX! Very cool.

Welcome to the forum and the crazy. Great pics. Even fuzzy, uber cool and thanks for posting.

 

[unknownbmxa88]

ill post more of my rat bike in another place, kinda put it on the back burner because i started the f/s. i plan to put another motoron it but for now i can only afford one honda, so its going on the MTB.

i guess the frame i have is SUPER uncommon. made in canada too apparently...gotta be better then taiwan.


and i forgot to add, just ordered a bunch of goodies from SBP and staton-inc to start work on the drive train, i hope to finish mounting the motor this weekend. im going to have very wide cranks, cus the engine is about 12 inches wide. the valve cover is gonna be pointed at my nuts so no over reving for me.

the bike itself only wieghts about 30 lbs and with the honda weighting 8 lbs according to the specs, and the trans is a couple and ill add a couple sprockets, but im hoping to have the entire package wiegh less then 50lbs, before i put gas in it. the gx35 had plenty of power even though i weight more then 200lbs, i think gearing low is gonna be the key,

at the end of the summer my goal is to drive a mountain pass that is about 30 miles from my house and back. stuff that my jeep barly makes it over. so this would be a pretty ambtious goal to say the least, buti think its deffinatly possible, that lil honda is awesome.

 

[unknownbmxa88]

i so got the motor mounted in the frame today. this thing weights lighter then some of my other bikes that dont have motors on it. im gonna weigh it when its complete, its gotta be like maybe 40 lbs, if that even. i know still lotsa parts to add but its off to a good start. thank god for dremel tools. best 20 bucks i ever spent at a pawn shop..

heres a couple of pictures. i used some scrap angle iron and 1inch square bar and a couple of muffler clamps from o'rileys auto parts. still waiting for the SBP parts i ordered should be here mid week, but ill be busy till next weekend with school and tax season.







another interesting thing i found the other day is this guy who uses two front freewheels to allow the bike to pedal without cranking the motor, and the motor to power without cranking the pedals.

if i understand it correctly, all i would need to replicate this would be a threaded peice that the freewheel would fit on, connected with a spacer that was countersunk, and had the 5 hole pattern that the next freewheel. i might try and see if a local machine shop can create this without charging me more then 50$,
this would be awesome so i could still ride the bike like a bike if i felt like it.

 

[Wild Bill]

I cant wait to see this thing when its done! Keep us updated. And maybe a video of a test ride.

 

[unknownbmxa88]

wait untill i finish the drivetrain...going to keep my front derailer, and hopefully run a dual front freeewheel so i can pedal the bicycle and it wont turn the sprocket on the engine.

like this:

http://endless-sphere.com/forums/viewtopic.php?f=28&t=15529

 

[Dan]

Awesome UKNBMX. Really like where your going with this. Gonna be a great build.

 

[unknownbmxa88]

update: yeah it runs good and fast, but i hate jumping and skipping rear chains... solution: NuVinci!!! 360% is more range then i have now and i barly use the high range as it is... so ill update this when i get it but im ordering the nuvicni soon and painting the entire bicyle with pasti-dip, olive drab color to be exact. lots of improvements, but ill post it when its done for sure. i had to redo my motor mounts, and im sure ill have more improvements since i got a job at a machine shop recently....with no experience...lol. but yeah. its epic is all i can say, and this thing cooks for only having 35cc.

 

[unknownbmxa88]

update: yeah screw the stupid nuvnci hub. to expensive. fount out that my casseette is just waring out and im went to CL to get a new one and i found it. ill post pictures of is this weekend, after it get a fresh cost of paint.

 

[Wild Bill]

Looks great! Ya, those hubs are pricey!

 

[KCvale]

update: yeah screw the stupid nuvnci hub. to expensive.

I have built 5 NuVinci hub based shifters, 1 dev kit, 4 of the ummm, 170S's I think that came on Cadillac bikes, unreliable overkill bud.

A 3 or 5 speed internal is all you need and if the bike doesn't have a good at least back V brake get a hub brake one as a coaster is useless with a shift kit, you can't back pedal.

I have a Suremy Archer 3-speed with a band brake on the way for a 4-dtroke 7-speed conversion but one thing I can tell you from a few dozen shifter builds is multi-sprocket derailleurs suck.
Thin chain, iffy mechs, and just shear wear shifting sprocket to sprocket under motor power.

Just my advice, take it or leave it.

 

[unknownbmxa88]

I have built 5 NuVinci hub based shifters, 1 dev kit, 4 of the ummm, 170S's I think that came on Cadillac bikes, unreliable overkill bud.

A 3 or 5 speed internal is all you need and if the bike doesn't have a good at least back V brake get a hub brake one as a coaster is useless with a shift kit, you can't back pedal.

I have a Suremy Archer 3-speed with a band brake on the way for a 4-dtroke 7-speed conversion but one thing I can tell you from a few dozen shifter builds is multi-sprocket derailleurs suck.
Thin chain, iffy mechs, and just shear wear shifting sprocket to sprocket under motor power.

Just my advice, take it or leave it.

yeah im exploring my options. i really like having a disc brake in the back, but i also like the new sturemy archer 8 speeds.
325% gear ratio internal drum brake and disc available i think but thefirst gear is direct drive so i would need a big sprocket in the back because i have to go through a lot of reduction to get low enough for what i want...off road and rough roads.

do you know whats the biggest sprocket you can get for one of those hubs?

 

[KCvale]

Sure disc brakes are good if your bike frame has a mount for the caliper, if not get a band brake, a 90mm band will stop you just as good and you don't have to keep replacing expensive dime size disc pads ;-}

1st gear on any shifter is not 1:1, the middle gear is 1:1, all the lower gears are under-drive, all the upper gears overdrive and any range over 200% is really plenty with a motor.

I find just a stock 18T sprocket on the hub to be just dandy with an SBP shift kit but a note about the 4-stroke kits... They come with a small BB rear chain drive sprocket, have them put the larger one they use on 2-stroke kits with it if you want a better top speed as with the 4-stroke shifters I've built I run out of gears long before I run out of power with the little front sprocket, note I do this for the electric shifters as well.

 

[unknownbmxa88]

yeah i was refering to the 8 speed hubs that are direct drive at first gear. im using a 35cc with a centerfugal clutch so it changes things up a bit. im looking at the 5 speeds now and they have a 37% drop on first gear...sounds like they could work for me.. how many miles do you have on your hubs? any failures? im kind of hard on my bikes. lol i jumped my motorbike yesterday going like 20

 

[Trey]

unknown- That pass your talking about isn't Flathead by any chance?

 

[unknownbmxa88]

unknown- That pass your talking about isn't Flathead by any chance?

yup. gonna try to make it by the end of the summer. i know its probaly impossible without a spare everything but why not, its worth a try lol

 

[unknownbmxa88]

i drive it in my jeep all the time.

 

[Goat Herder]

Sure disc brakes are good if your bike frame has a mount for the caliper, if not get a band brake, a 90mm band will stop you just as good and you don't have to keep replacing expensive dime size disc pads ;-}

Nope they will not compare at all to a 185 or bigger rotor. The cheaper variates that come from department stores with tiny rotors no doubt yes...

Lemme run some higher power engines in them shifters. lol They will lie down. I've done it..But then of course a higher power motor does fine with one gear and a centrifugal clutch in my experience..Just stay away from some of the China stuff. Tomar works perfectly!!

 

[unknownbmxa88]

the BIG reveal!





my 2006 rocky mountain element.

this build is totaly different from using the china kits, and the shifter kits, this was completely DIY. motor mounts to figuring out how to shift. i choose a honda gx35 mated to a pocket bike 5:1 reduction trans. i grinded down the output shaft to 3/8 and cut in a key slot. next, i bought a 9t 410 sprocket with a key slot and taped for allen keys. the pocket bike trans sprockets are only avail in 12 and 10t, the 10t's from DAX being no heat treated stamped out of tin foil, were useless i went through one in a week. the 9t powers the fromt sprocket sized 48T. the main difference between this bike and the shift kits, is the fact that i have a reversing output shaft trans, so i had to mount the engine air intake forward, backwards from the kits. this allowed me to go directly to the from sprocket only using 2 chains, but to acheive enough reduction i have to reduce in my bicycle gears. not a big prob. the 48t is conected to a 24t and the 24t powers 34-11t 9 speed cassette. i plan to reinstal my front derailer so i will have 36 and 24t in the front. this would be optimal for riding it like a bicycle which is still very easy since this entire build weights very little i would guess less then 50lbs dry. the gas tank is a go-ped 1.5 liter mounted on a front rack. rack 20$ tank 35-ebay. this is a two line carb engine so this tank works well. the nice thing about the gx35 is it can suck gas into it so i could literaly put the gas tank anywhere. the handle bars are fly racing for a pit bicycle. forget which ones i found ones with the goemetry i liked. the air cleaner is for a pocket bike carb slightly motified to fit the gx35. pull start. at the moment it has a very short pipe, its very loud. i am planning on routing the exhaust around the bottom to the other side and over the trans and come out under the seat, and ill get a silencer for it, to make the hippies happy. people always cover their ears when i go by but i think its good cuz loud pipes save lives. most of the parts i got from SBP and staton.

ill post a video of riding this thing as soon as i can

this thing does 25 up a hill, easily 40 on a downhill and goes 30 on a flat no prob. im sure it will be faster after i finish my exhaust. and im no light fella. i weigh 225 lbs. lol.


im thinking of adding a 38t for the first gear. im thinking of setting it up so ill have a super low first for off road and steep steep hills and wheelies. lol.
but on flat or at a light the 34t is great for starting at the moment. there available on ebay, and since im running a cassette, ill just simple toss a lower gear. so ill still have my 11t. and ill have 38-11t. thats a huge range.

 

[unknownbmxa88]

oh and i forgot the finish is plasti coat in camo green. takes two cans to do a bike and its kinda pricey, but i like it better then rattle can. and it seems durable, its a rubberized coating. smothing like bedliner or rynoliting i guess more then spray paint but the cool part is once you get it started it peels off. we will see if it lasts.