rat bike pictures 1936 Hawthorne

As promised here are some pictures of my previously mentioned rat bike.It is torn apart right now since I am working on modifications. The copper tubing in the first picture is part of a new tank mockup.

It is a 1936 Hawthorne frame, 1950s Monark springer fork, 1930s schwinn brakes: front drum, rear cantilever, 9 speed rear hub: Sturmey archer AW threespeed hub with a cyclo triple hub sprocket shifted by an mid 1960s chrome plated bronze Campagnolo Record derailleur. I modified handlebars from a small dirtbike by brazing a Campagnolo braze-on downtube shifter, and brazing on cable guides made from the inner rollers from bicycle chain. The 1950s era three speed hub is shifted by a 1930s vintage top tube shifter mounted on the handlebar.

The front hub is a 1930s Schwinn drum brake. I originally built this bike as a mountain bike prototype in 1980. All the parts except the front fork, rear hub and derailleur, alloy rims and tires, and handlebars were made before WWII. I built the wheels at this time with the only 26X1 1/2" rims alloy rims available: Araya. I made a headbadge from an emblem off of some old machine , thus conceiving a bike brand that never was.

I rolled it to fit the radius of the headtube. I used a Monark springer fork off of a girls bike because of it's longer steering tube. I put large washers between the forkcrown and the crownrace to lift the headtube and give more bottombracket clearance since this was an off road prototype. The frame is from a Hawthorne brand bike which was sold by Montgomery Ward. It was made by Cleveland Welding Co who made many brands for numerous companies. When I first got a chinese motor, I was planning to put it on either an old Schwinn straight tube or a phantom frame, both of which I had lying around. Both these frames had curved downtubes and I didn't like the way the motor fit the either frame. The rat bike has straight down and seat tubes and they were at the exactly correct angles to fit my motor without modification. I don't like the way the teardrop tank fits this frame, so I am in the process of making a tank to fit between the toptubes. I also didn't like having two left handlebar levers(1 clutch, 1 brake). I didn't want to use a twistgrip type clutch control either. I ended up taking a barend gearshift lever and modifiing it to use as a clutch lever. It has more travel than the stock lever and is adjustable for tension. I have it rigged to run in the down position(out of my way) and disengage the clutch in the up position. This is still out of my way but increases the width of the handlebar by 1.5 inches. On most motorcycles the left lever is the clutch and the right lever is the front brake. On most bicycles the left lever is the front brake and the right lever the rear. I decided to go with the standard bike lever setup, since this is more bike than BIKE. I have a few more pictures which I will post right after this.
mockups and more

I got some time to work on my ratbike today. I made an aluminium air cleaner cover. I didn't like the plastic one on my old bike. I also tweaked the induction system. I deburred the intake manifold, ground out all the weld intrusions on the inside of the manifold and matched the mounting flange more closely to the intake port. I makde a new gasket out of american made gasket paper. I lapped the mating surface of the flange. I am planning to replace the studs with higher grade metal.

I made a head pipe out of 3/4"EMT. I carved a wooden dowel to fit the shape of the exhaust port and then used it to form the cylinder end of the headpipe.



I also mocked up the fueltank. I plan to extend a cdi cover behind the tank , but visually integrated with the tank shape.
Hi, When you mentioned the words British Thumper I flashed back to my teens and a 441 Victor BSA I used to ride. Man I loved that bike it had some tork I'll tell you. What a ride. Anyway I bought and received the Monarch type springer front forks and they bolted right up and look and work excellent. Thanks for steering me in the right direction..... Tom in WV

Limey bikes, that brings up lots of memories. My first bike was a triumph bonneville a friend gave me with a siezed engine. I had to bore it to 0.070 oversize. Fortunately the bottom end was undamaged. That engine had alloy connecting rods. I put it back together and got it running. A friend of mine really wanted that bike so I sold it to him. Then I got a 1950 matchles 500 single basketcase. That bike was really torquey. When riding on a dirt road, I could get the rear wheel to leave skid marks every time the engine fired. It had big "oilccan" shocks and a chaindriven external magneto. I sold that bike later to get money for a year long travel adventure. I sure wish I still had this bike. My last British bike was a BSA works trials bike. It used the same frame that would later be used on your 441 victor, but had a special non-production 250cc engine that produced more horsepower than my old Matchless 500 had. That bike was sort of like a cross between a tractor and a roto-tiller.
" found" tank, hammertone finish, some light shaping for a Hawthorne frame.

loving these builds guys, I just wish i could get hold of those girder forks for my triumph, girders seem bit rare over here?
Triumph, why don't you build one. I made a copy of the fork on the bike pictured in this post for another cycle. I started with a forged steel fork and straighted it. Then I took a second fork and sawed off the steering tube. I then welded long bolts to the crown of the second fork for spring mounts. The next step was to make the links with axle slots(dropouts). The final fabrication was to make the upper spring attachment.
progress report

I just finished replacing all but the long studs of the rear motor mount with automotive grade studs. I had to grind down the the engine end of each stud to match the depth of the internal threads of the engine. The long studes that came with the engine were longer than any replacement studs I could find locally. I made replacement studs by cutting the heads off of the correct length high grade bolts of the correct thread. I tapped the unthreaded end of each bolt the the thread length to fit the engine threads. I am in the process of machining an adapter to permanently mount to the hub, with provision to remove the sprocket without disturbing the adapter. This will make it easy to use different sized sprockets without the tedious process of centering the rubber and bolts stock mounting.
ratbike update

I've been too busy to spend any time on my bike lately between helping my friend Pat with chainsaw carving a rush order for a seafood resturant and a three day break to do a 40 foot long shark sculpture out of snow at a ski area last week.