Honda GXH50 on Cook Bros. Cruiser Bike

[Joaquin Suave]

I'm going to mount a GXH50 onto this cruiser bike that i receintly bought at a local garage sale, but the problem is that the motor dosen't quite fit under the middle tube...Do you guys think I can cut the middle tube out and have the frame still be strong enough for my 220lbs? Other bikes don't have a center tube and do just fine, right?

Thanks in advance! I've been doing a lot of lurking...And DANG some of you guys have cool rigs!

 

[SimpleSimon]

Well, maybe

You are correct, many bikes do not have the mid-tube stiffener, but there are sound engineering reasons why that may be required in that frame.

The first consideration is geometry - the top tube and the down tube are both fairly long for their cross-section. Depending on actual tube material and wall thickness, it may be a necessary brace.

Second is a "strength of materials" question having to do with a peculiar fact of tubular structures - to wit, a tubular structure of any material of a given wall thickness and cross-sectional properties will be stronger under load if pre-loaded with a fixed curvature rather than being straight. The down tube in that frame is straight.

You can probably get away with removing the tube, but it WILL weaken the frames rigidity. What you might could do is replace it with a tube arcing up to allow engine clearance but still carrying the dynamic load.

 

[ocscully]

I'm going to mount a GXH50 onto this cruiser bike that i receintly bought at a local garage sale, but the problem is that the motor dosen't quite fit under the middle tube...Do you guys think I can cut the middle tube out and have the frame still be strong enough for my 220lbs? Other bikes don't have a center tube and do just fine, right?

Thanks in advance! I've been doing a lot of lurking...And DANG some of you guys have cool rigs!

You might want to do some checking into the Value of the Cook's Brothers before you start cutting into it, cause once you start cutting it will be out the window? Those bikes can bring in prices in the thousands of dollars on e-bay and else where (Old school BMX, Early Mountain Bike Collectors). You could build several bikes for what that bike is probably worth. It appears to have all of the Cooks Parts still there. The Cranks are Cooks Cranks at least 180mm or longer (Rare) I'm sure the BB and Spindle are Cooks as well. The Stem is also a Cooks and probably the bars. I'd also guess the rear hub is a Cooks as well? That's a Very Special Bike! Do an e-bay search for Cook Brothers and have a look at some of the $$ parts and complete bikes are currently sitting at, before you cut out the tube on that bike. The if you decide that you still want to throw a motor in it, well at least you will be making an informed decisionn

ocscully

 

[Joaquin Suave]

GEEZE-LOUISE!!! I had no clue...

A buddy of mine at the local "watering hole" said that the bike was worth big bucks, but I thought he was just feeding me a line of sh*t. I guess he was right. I checked ebay and some of the cooks bros. parts are worth more than a whole new bike!

I think I'll leave that bike alone and find another one without that center tube.