Hello from Southen California

[KCvale]

View attachment 56070

Today, I changed my mind and bought a cheap, but cool looking bike.

Wally World's vintage-replica of the 1937 Columbia. I'm sure, it's a very cheaply made bike, but, when I saw that mock gas tank, I couldn't resist the temptation of building my own fiberglass tank inside. I hope the bike holds up. It had a scratch for 10% off and I opened a Walmart credit card for another $25 off. Heck, you can't buy a used, beat-up bike on Craigslist for that price! It might be a good bike on which to get my motorbike feet wet.....

I plan to simply screw a wooden floor to the top of the bottom bar, put my form-fitted fiberglass tank on it and build the sides around it all. If I pull open one side to fill the tank, I don't need to mount a gas cap ON the outside of the bike, and I can use the space at the front and back of the tank to store oil and tools. But, the "devil is in the details" and I've got a lot of fine details to work out.

Any design ideas are very welcome.

Jim

You have seen my 1937 design for making the fake tank real, and the free rag joint mount fits just right.
I like the spoke mount adapters, do them right and they essentially make your hub 3 or 4 times larger, thus less spoke length to the rim where the power goes.

On the down side only one side of the spokes are driving the rim directly, but the other 18 spokes indirectly power the rim via the bottom of the spokes connected to the hub.

A hub mount is great for wheels without 36 spokes, necessary even.
I am just not a fan of something that relies on gripping the hub solely on bolt tension grip, to me it's like any sprocket on a shaft without a keyway.

With rags on both sides of the spokes, which are just cut out of heavy machine used tire sidewalls has 18 keyways on a 36 spoke wheel.
It can't spin free and the apparent reason for the flange with another friction hose clamp to help.

No, you NEVER mount a sprocket right against the spokes.
It's a sandwich that adapts to the spokes on both sides.
just square it back up after 5 miles or so once everything seats in to what is essentially a solid piece.

I won't bad mouth hub adapters, and the hub adapter that mounts to the spokes AND the hub might really be cool, by mount to the hub, but if it's that important to you can get a whole new hub with everything for a 36 hub drive and a band hub brake and sprocket for $50 here.
http://www.gasbike.net/bike-motor-engine-heavy-duty-axle-kit-non-free-wheel.htm

But you'll need to get re-laced so figure at least $75 for a pro to do it.
And look at big vendors, some may have the Grubee complete new back wheel for under $100.

Just thoughts for you to consider if you don't think the free stock sprocket mount will work.
For me they work dandy, stay true, and already paid for in the kit price.

It's easy to toss money away on something advertised as better or easier, most may be worth it except things like boost bottles, but overall for most just wasted time and money in my opinion.

 

[PocketBiker]

Yes, the clamp on flange, as you put it so well, is like a "shaft without a key way"..... a bit of a design problem.... Like holding onto a greased pig. My intuition kept leading me back to the kit method in security and simplicity and even..... $$. After I included the photo of the $45 method with the rubber and the hose clamped flange around the axle, I realized, after looking at it again, that actually the flange around the axle would do relatively little to align the sprocket, because the sprocket is still mounted on rubber.... It's like, it tries to align the rubber perfectly, but the rubber, is still....... RUBBER!

I will go with your advised method.... your help is invaluable to me! KC, I wanted to ask you, would it be a good idea, if I filled the 1" or so area between the front engine mount down to the frame with a shim and just solidly U bolt the front of the engine directly to the large frame tube with one or two U bolts?

Jim

 

[Wolfshoes]

I could suggest using a steel front engine mounting bracket. The commonly offered U shaped small tube to large tube mounting bracket appears to me made out of cast iron and therefore, less resistant to vibration in my opinion. Also being U shaped, there is not enough metal around the screws to provide a visible warning that the part is cracking. The only known backup for the front mount that I know of, is the exhaust pipe to frame or subframe hardware. If this hardware is not used, often included in the motor kit, there is no backup of the front mount. This hardware included with the Gasbike kit is chrome plated and looks better than what is pictured in their online catalog.



I could suggest an alternative mount:



Perhaps a upper mount:



This picture also shows clamping the muffer bolts and the front mount of this Landrider bike where the motor was filed to fit the frame and what is remaining of the front mount being trapped between to clamps ( I like clamps). It's been in use this way for two years. No bolts.

The use of muffler clamps could be considered optional on builds where the front of the motor directly connects to the round frame tube. Providing you don't mind that the exhaust falls off from time to time. The odds of a front mount failure would be low to not at all. S curve frame builds are a different story. Instead of the motor casting directly wrapping the frame tube, you are relying on a pile of brackets and a couple of 1/4 inch bolts being hit with vibration. With this much weaker connection, the muffler clamps are the last line of defense against front mount failure and in my opinion must be used. To bring your Columbia bike engine install to typical standards of safety; the parts included in the Gasbike kit; the kit I am familiar with, are safe enough without any other modifications. The big debate would be, is this safe enough or is the two exhaust bolts to the engine compromised by vibration to the extent that there is a risk these fasteners would also fail if the front mount failed. Grubee may have good reasons for discontinuing custom S curve frames, selling them at a big discount, changing the casting of their motors to large tube support and building frames with straight front tubes. For safety reasons, when it comes to china girl engines, S curve frames may be going the way of the dodo bird.

 

[PocketBiker]

Wolfshoes,

I'm still going to call you "The Gilligan's Island Professor." What you lack in beauty, you make up for in functionality!

I don't know what most people do as far as supporting the muffler. Logic tells me it would be a good idea and that metal tubing you have just above the pedal is secure as can be. I don't know that I really understood your comment about the S curve frame going by the wayside? For sure, two small frame tubes in a V shape would be ideal for our little China Girl, but I don't see the S curve as a problem that can't be solved, quite easily. No, after thinking about it, that large S curved tubing is anything but a deal breaker.

I enjoyed seeing your solutions..... They could have used you on the Apollo 13 mission.... you would have had everything in working order in minutes!

Right now, I'm working out the problem of venting the gas tank. I will build baffles inside my tank to keep the fuel from sloshing too much. (That's not going to be too difficult with my fiberglass tank) but, I'm thinking of running a separate (and higher running) vent tube from the top of the fiberglass tank to avoid spillage of fuel. I know there is probably an easier way, but we "Noobs" have to keep reinventing the wheel.

 

[KCvale]

KC, I wanted to ask you, would it be a good idea, if I filled the 1" or so area between the front engine mount down to the frame with a shim and just solidly U bolt the front of the engine directly to the large frame tube with one or two U bolts?

Jim

It's never a good idea to bolt something flat onto something round directly.
That's what muffle clamp piece is for.
It's round to grip the pipe on one side, and flat on the other.

 

[PocketBiker]

engine mount

It's never a good idea to bolt something flat onto something round directly.
That's what muffle clamp piece is for.
It's round to grip the pipe on one side, and flat on the other.

I understand that. My job is holding me hostage for the next week. I'll design it and show it later...... Have a productive weekend.

Jim

 

[Wolfshoes]

Just thought I'd throw this idea out there as a tank option. A commonly available rear motorbike tank may work better on edge up front than as a rear tank. As a rear tank the outlet is on the wrong end. To modify it to work on edge may be easier, lighter, cheaper than making a tank. The continuous weld seams would predictably hold up in the event the tank is bent. Perhaps it could fit behind decorative covers. There is no 1937 model bike at the local Walmart to do a quick measurement, but it looks like it could fit. The tank measured as mounted on edge above engine, including 3/8' weld flanges is 14 1/2" long, 5 1/2" tall, 2 1/2" wide with and additional 1" wide at the point of the outlet. Perhaps instead of an outlet petcock, the tank could be used with a intake manifold or crankcase vacuum powered pulse pump that would suction the gas out of the top of the tank.



Also I could suggest a steel wire safety strap be installed on the front of your motor looping around the large s curve frame tube to provide some protection in the event of front motor mount failure. Two holes could be drilled above the tube mount in the front of the motor to provide a independent attachment point for the safety loop.



Granted drilling the front motor mount is not totally above reproach, but there are few options to attach a safety strap and the benefits may out weigh the risks. Seems to me race car engines and chained in to protect against mount failure and car trailers are chained to protect against hitch failure. There may be no acceptable alternative to the China Girl engine casting directly connecting the bike frame tube and when these modifications are made, added insurance may be called for.

Your selection for a tensioner looks good since it mounts the round frame tube in three places. Perhaps the engine can be mounted in a way the tensioner is not needed; so I would not be quick to buy it.

 

[PocketBiker]

Engine Mount

I am away from home for a few more days, but I have planned out how I will build the gas tank. I am looking forward to shaping my tank out of foam and fiber glass because it will allow me to use every bit of space rather than compromising by using an existing tank. I'll post my build of the tank, maybe next week. ??

And, I've thought a lot about the mounting of the front of the engine, since the engine is about 1" away from the front down tube. BikeBerries' universal mount (below) looks pretty good, but I thought I'd just find a 3/16" 3.5 X 3.5 approx.flat piece of steel and drill my own holes to exact dimensions of my down tube. I'm also guessing that MY U bolt distance may need a longer U bolt than that which is supplied.... and, as KC suggested, I'll find a couple of muffler clamps..... photos to come.

I'll use a flat piece of 3/16" steel plate, but the photo below, shows BikeBerries' adapter plate which would probably work fine too......