Twin motored PK Ripper--A little over the top!

[12p3phPMDC]

Walsh,
Both those bikes you posted are really cool.

The rear suspension geometry of the STS is awesome.
It is one of the cleanest moutain bike suspensions I've seen...(not saying much )
Very uncluttered and classic looking in terms of rear forks.

It appears that you can control the degree of the rising rate (if it is rising)
by rotating the top mount of the coilover in its slot.

That Yamaha would have made you a bmx bike superpimp in 1974 or 1984 for that matter.
It's still cool....

 

[recumpence]

I now have the cash to produce the drive unit clamps finally!

My CNC shop is booked untill early July. After that, drive unit frame clamps will be produced.

Welcome to the board, by the way.

Matt

 

[walshcore]

I now have the cash to produce the drive unit clamps finally!

My CNC shop is booked untill early July. After that, drive unit frame clamps will be produced.

Welcome to the board, by the way.

Matt

Hi Matt,

Thanks for letting me know about the drive clamps...now i'm getting excited about the new sport of 'uphill' mountainbiking!!! ... would you have any idea if that carbon framed GT i posted a pic of is going to be suitable for one of your drive kit? do the clamps require a hell of torquing up?

Cheers,

Walsh

p.s just noticed a missing word in my first post...i omitted the word; ski after jet, i wasn't trying to suggest many people have jet planes lying around their garages gathering dust!! lol

 

[recumpence]

The issue I see is the odd shaped tubing.

Carbon tube is crazy resistant to crushing, though. We use carbon tube for RC heli tail booms. The clamps that we use around that tube are cranked really tight.

If the tube is round, it will tolerate an insane amount of clamp tension.

Matt

 

[walshcore]

The issue I see is the odd shaped tubing.

Carbon tube is crazy resistant to crushing, though. We use carbon tube for RC heli tail booms. The clamps that we use around that tube are cranked really tight.

If the tube is round, it will tolerate an insane amount of clamp tension.

Matt

Matt Unfortunately the carbon tubes are not a consistent shape. The best way I could describe it is as an "irregular" oval...kinda like a diamond with rounded corners. I assume this perhaps would rule this frame out for mounting a kit? what u reckon?

Cheers,

Walsh

 

[MitchJi]

Hi,

The issue I see is the odd shaped tubing.

Carbon tube is crazy resistant to crushing, though. We use carbon tube for RC heli tail booms. The clamps that we use around that tube are cranked really tight.

If the tube is round, it will tolerate an insane amount of clamp tension.

Matt

Would it work to build up the Carbon tube with more Carbon Fiber to make a small section round for the clamps?

It would probably be best to remove the paint and either scuff up the surface or possibly drill some small holes (additional thicker carbon would restore the strength?) for proper bonding and to prevent rotation.

If that would work with a Carbon Fiber Frame would the same technique also work with an aluminum frame?

 

[northernmike]

Carbon in that shape would not react well to being clamped to, in my opinion.

Carbon fiber composites are generally engineered to take advantage of the fabric's TENSILE strength - so fibers are arranged in such a way that the expected forces try to "stretch" the fiber along it's length.

Carbon fiber composites can be very brittle when hit perpendicular to their designed stress direction.

This is why Kevlar is often included in CF laminates - to provide some flexibility.

Adding "more" CF will not solve the problem - I'd stay away from a pure carbon frame unless you stick with the engineered stress points + directions.

 

[walshcore]

Damn...i love that frame!!......anyway back to the drawing board me thinks!!....cheers for your thoughts anyway guys

 

[liteCycles]

Somebody tell me if I'm totally wack. I heard that JB Weld has a nice paste like consistency. OK you probably know where I'm going with this -

1. Get an aluminum clamp a little oversized.
2. Wrap frame area with Saran Wrap.
3. Put JB Weld on the inside of the clamp (roughen up alum for better adhesion).
4. Place on bike with slight pressure.
5. Check of proper alignment.
6. Cure.
7. Remove from frame.
8. Sand off excess and polish to your tastes.

This is a take off on that rubberized compound technique an Orthodontist uses to make an impression of your teeth. Or two part marine epoxies might work. Shoot I used a crack filler on my basement floor the other week that was easy to work with and came out looking great. And I'd put tape on the exposed areas of the clamp to minimize the amount of clean up in step 8.

Possible refinements could involve using different thicknesses of old bike tubes on the frame in the curing and final assembly stages to end up with a vibration resistant solution. The rubber could be shaved with a razor blade to match the exact size of the clamp for a clean professional look.

Jeff

 

[recumpence]

The buyer of the PK just came by. I changed the sprocket for him. It is now geared for about 50mph or so. He wanted more speed and less poke. So, now the LV cutoff is acting like a current limiter. The bike still wheelies even when leaning over the bars. But it does not snap really hard anymore. It was actually a joy to ride without such violent throttle response.

My KMX will definately have a huge amount of hit, though. No worries about wheelying on that. :wink:

Oh, he is having huge fun with it. I am happy about that. I did not want to sell a project bike that did not deliver.

Matt

 

[methods]

That is totally gangster... I am going to try it.
How come I never think of these things :?

-methods

Somebody tell me if I'm totally wack. I heard that JB Weld has a nice paste like consistency. OK you probably know where I'm going with this -

1. Get an aluminum clamp a little oversized.
2. Wrap frame area with Saran Wrap.
3. Put JB Weld on the inside of the clamp (roughen up alum for better adhesion).
4. Place on bike with slight pressure.
5. Check of proper alignment.
6. Cure.
7. Remove from frame.
8. Sand off excess and polish to your tastes.

This is a take off on that rubberized compound technique an Orthodontist uses to make an impression of your teeth. Or two part marine epoxies might work. Shoot I used a crack filler on my basement floor the other week that was easy to work with and came out looking great. And I'd put tape on the exposed areas of the clamp to minimize the amount of clean up in step 8.

Possible refinements could involve using different thicknesses of old bike tubes on the frame in the curing and final assembly stages to end up with a vibration resistant solution. The rubber could be shaved with a razor blade to match the exact size of the clamp for a clean professional look.

Jeff

 

[CNCAddict]

Hmm, maybe some of this would work https://www.mightyputty.com ??? Billy Mays to the rescue! JBweld is really a liquid compared to epoxy putty.

 

[MitchJi]

Hi,

The paste looks better to me than the JBweld.

If that doesn't work maybe HTS-2000 would work?
http://www.aluminumrepair.com/

Anyone Can Repair Aluminum Quickly and Easily with HTS-2000 Brazing Rods
The Strongest, Fastest, and Easiest Aluminum Parts Repair.

Will it work for your job? YES! This high-strength brazing rod allows you to repair or fabricate aluminum stronger than a Tig welding machine, without the machine. No welding aluminum needed! All you need to repair any metal stronger than new is a heat source (propane or mapp gas), a turbo tip, or oxy-acetylene, and our material. This new repair technology performs well on aluminum, cast aluminum, pot metal, copper, magnesium, and all white or porous metals. You can easily repair corroded or oil-impregnated areas that can be next to impossible to fix using welding machines with aluminum welding rods or other brazing products...

Imagine getting stronger, better results than welding, by using our high-strength brazing rods and just a torch—the kind of propane or mapp gas torch you probably already have or can easily pick up at your local hardware store.

I'd try:
1. Wrapping/pounding thin aluminum sheet tightly around the frame.
2. Drilling a hole or (to get a better fit) drilling and grinding a hole in a solid piece of aluminum, large enough to fit the aluminum sheet.
3. Put the sheet in the hole in the solid piece and fill the gap between them with HTS-2000.
4. Cut it in half and drill holes to form a clamp.

 

[recumpence]

Hey Guys,

I just got a call from the owner of the PK. With my regear for him, it is confirmed 52mph while still having plenty of wheelie power. Also, it handles fine at that speed.

I gotta build me another one...............

Matt

 

[The Stig]

Hit a bump at 52mph with that thing...

Is he gonna put a suspension fork on the front?

 

[recumpence]

Yup, I have one on order for him.

He does not ride it fast for very long. I think he is a 40mph guy who just wants a bit more speed once in a while.

He does like fast motorcycles, though. :wink:

Matt

 

[Link]

Hi,

The paste looks better to me than the JBweld.

I was dead sure that "BILLY MAYS HERE" was what came after the "Hi".

 

[mud2005]

front suspension eh? what forks did you order?

 

[recumpence]

White Brother's RC80 20 inch forks for disc brake.

Matt

 

[mud2005]

White Brother's RC80 20 inch forks for disc brake.

SUPER nice!

 

[voicecoils]

White Brother's RC80 20 inch forks for disc brake.

Matt

Nice choice! White Brothers make a suspension fork for almost everything from 20" wheels to 29ers. They've been catering for EV's too and are used in both the Zero X and Stealth Bomber Cool to see that you've become a dealer for them!

 

[Byte]

Sorry for kicking this thread to the top again But I just road the whole thread again, just like I did about 3 years ago and again I got one BIG smile! This one is one of the most beautiful bikes on this forum.

One little question though: Would a single Astro 3220 on 12S LiPo have more power than a twin Astro 3210 on 12S LiPo?

 

[recumpence]

Funny you would bump this thread. I am building another 20 inch bike way beyond this one. The frame is at the powder coater right now.

A 3220 would have the same power with better efficiency.

Wait till you see this new bike!

Matt

 

[Ypedal]

2 motors = 2 controllers...

1 motor = 1 controller..

a consideration ! :wink:

 

[Byte]

Hehe I was searching for this thread a while back, but couldn't find it. Today I accidentally bumped on it, and road through it again, just because it's a beautiful build! Matt, you probably don't want to give away which motor/esc you'll be using in the new bike, do you? New 4" Astro?