lyledriver

I'm currently starting to build a new chopper/freak bike, and thought I would do a build log.

The idea for this bike is pretty simple. I want a bicycle that looks like a hillclimb motocross bike (ie long swingarm). To do this, I'm simply adding a box section rear end to a BMX frame, and mixing in some MTB components.

This was my MSPaint concept sketch:


Parts I'm starting with:
-K2 Rake chromoly BMX frame 21"


-bmx bars (above pic)
-3 piece Diamondback unsealed cranks (Powdercoated gunmetal, also in above pic)

-.243 Racing Freeride dropouts w/ disk mounts, derailleur hanger and chain tensioners


-Rock Shox Jett fork (60mm? Elastomer?)
-Haro polished Frontload BMX stem
-Kink 44T sprocket
-26" MTB front wheel
-20" 14mm axle BMX rear wheel
-mismatched V brakes with Gorilla brake booster
-10' of box section steel tubing

Where I'm at:

I've purchased the Box section (1.5" x 0.75") tubing from our local metal supply, and cut it into 2.5' sections. Yes, the rear stays will be that long.

I've cleaned up the 243 dropouts to remove all welding from the previous stays and make them a uniform thickness.

The rear end is chopped off the K2 frame, and I'm still cleaning up what is left of the stay welds.

I'm trying to figure out the geometry of the rear end at the moment too.
I want it to be spaced 120mm. I think this will give me the greatest range of adjustability, in terms of rear axles. I may have to squash it down to fit a 110 BMX hub in there, or spread it out to fit a 135mm MTB rear axle.

At present, I've got an old BMX rear wheel, with a 14mm axle. The picture of the dropouts shows them being held up by a 14->10mm flatted axle, but I won't be able to use the 243 chain tugs with it. Plus, the flat spots are spaced at 110mm.

I'm going to keep the stay bridges far enough away from the dropouts that I can fit a 26" wheel in the back as well.

I am also trying to work out the bottom bracket height.
As this bike will mostly be for cruising/goofing around, I think I'll keep things slack.
I'm going to try to have the seat stays along the same plane as the top tube.

Oh, and as far as colours go, I think I want this thing to be bright.
I was originally thinking something like safety orange, or flourescent orange, but I've got a friend who is trying to convince me to go with Kawasaki green (as he's got a Kx-80 number plate).

I'll update this thread when I make some more progress =]

kemmer

Rock on, looks cool. I have to ask though, how are you going to do wheelies?

e-Man

Very cool looking project, I like the idea behind it. Should be a slick looking ride when it is done, keep us posted.

StokerPoker

just a wrod of warning, although I'm sure you know better.... Ape hangers and hill climbing don't mix! learned that one the hard way....

frameteam2003

put the rear bridge in last---I find it easer to aline the frame without the bridge.I also recomemd building the wheel and then butting the bridge close to the tire(no fender clearance) for strength.

lyledriver

Hrm.. interesting. I was just working out the trig tonight, for the stay length vs. spacing for the angle cuts I'll be making in the stays, and I still don't know what type of hub to use.

I'll have to decide that (hub spacing) if I want to make the bridge as close as possible to the max tire diameter.

Does 130mm make the most sense?

I should see if a friend still has his old cassette laying around.. then swapping over to a bigger cog could be a reality, as the dropouts are a few inches long=D

CmpsdNoMore

That looks totally sick!
Hope it works out well.

wethepeople

If you have any spare parts afterwards (wheels, pedals, stem, anything really) pm me. I cant wait to see how this turns out, I was going to do something similer but never put enough thought into it.

frameteam2003

Your chain type might be a consideration.Single speeds usually use a 1/8 but mulity freewheels use thinner(and weaker)chain.If this bike is going to have serious tork applied to it(like in climbing hills),then maybe a flip/flop BMX hub is what you want.If your only going to cruze a 5 speed block would work ,but also the front sprocket must take the chain used.--sam

lyledriver

^I'm definately going with a 1/8" chain setup, as my kink front sprocket is that size.. and I've got a few spare BMX chains laying about.

I've also got a few 1/8" BMX cassette cogs, from 16T to 13T that have the same spline as shimano.
I was thinking of just putting two of them on a shimano MTB hub, spaced out a little from each other, so I could stop and do manual gear changes.

As it turns out, my friend donated his old LX hub to 'Our Community Bikes'.. so that might be out.
I may have to use a Shimano 600 freewheel hub, with a BMX freewheel on it, solid axle'd and spaced out.

This weekend I'm going to start dremeling the stays to fit the dropouts/BB shell.
I'll post up pics once I've made some progress.

frameteam2003

With the shimano caset hub spacing at the rear---you could at some time later turn your kustom in to a retro-direct geared bike.I think your choist of hubs is a good choise

lyledriver

After much winter distratcion, I've resumed work on this project, and I intend to have it complete by the end of the month. I also have a new goal, and that is to race it in February's minibike winter events in Portland. Downhill, not up! .. on wheels no larger than 16"!

Last night I put a Tank headset in the frame so that I could mount up the fork, and begin working on the stays. I've aquired a dremel, and made some cardboard templates to match the curve of the bottom bracket, and angle of the dropouts. I'll have them shaped by the end of the week




Oh, and I ran out of headset spacers and didn't think I should chop the steerer tube just yet, so I threw a couple crown races and a cog in there:

Capn ¡FUN!

sweet! Looking forward to racing against that beast!

I think you should put a reall long banana seat on though.... you've got the room!

lyledriver

This weekend I went down to Pedalplay and really got to work fitting the back end together.
I cut the 4° 6mm slots in the stays for the dropouts, and angle-radiused them to the bottom bracket and seat tube respectively.






Its coming together pretty well so far.
Theres still some minor alignment to do, but its almost ready for welding.
Using the tow strap worked pretty well to hold it together while
mocking up, and was a snap to undo and remove a stay for filing.
(Though, it pulled the dropouts on a bit of an angle. The pix are not
of the final fit.)

I still haven't found a suitable rim to build into a wheel with that disk hub, but I'll be working on that this week.

nugenhipsta

that looks soooo sick already. ever consider an extremely fat rear tire?

mander

Looks ****in good Lyle! I'm glad you started this build log as i have been curious to see how the project develops.

lyledriver

16" closer to death:

wethepeople

Best.Wheel.Evar.

mander

uhh Yee-uhh

lyledriver

Almost there=]

ken cummings

That will be a nice cushy ride with the rider centered between the tires.

wethepeople

wheelie it.

Stacey

Excellent!

nugenhipsta

holy **** now paint the frame/front wheel like the rear wheel, and that will be without a doubt the sickest bike i have ever seen

jetta_mike

Hey Lyle,


looks like its coming together quit well. Whats the spacing on your front fork? I have a QR front disk hub siting here at home. I'm sure we could work something out.


-mike-