Motorcycle Frames To Be Stable - Or Not
Motorcycle frames have everything to do with performance and feel of the motorcycle. The motorcycle frame, suspension and engine are linked in the most critical way to deliver the overall riding feeling of the motorcycle. The modern day motorcycle are built on a variety of frames. With weight distribution, frame strength and geometry as very important components.

Frame Introduction
In the early days little engines were fitted to bi kes and declared motorcycles luckily we have come a long way since. The first pure mc frames were built from thin steel. Later the steel was pressed to give it more strength. The major battle of Japanese manufacturers to build more powerful engines left many frame too weak to handle them resulting in wobbly / weave riding characteristic.
As more strength was required from the frame, steel tube designs were introduced with the Norton Featherbed leading the way. The steel tubes were then triangulated to form a strong complex web in which the engine would rest. Later development saw the engine become a member of the frame as the steel tubes were linked with the stability of the engine.
Generally a cruiser or custom motorcycle will have a longer frame and the weight ratio more towards the back. This give the motorcycle a slower reaction time, bigger moving space and overall more easy going riding position. Sports motorcycles tend to have a shorter frame and the weight more forward. This makes the motorcycle steer sharper, react quicker and a more edgy riding style.

Useful Frame Tips
You'll find the following types of frames: classic steel tube cradle frame, large main spine frame, ladder of thin tube frame, twin aluminum spars frame.
Frames are made to be stiff, if a frame flexes the wheels aren't in line anymore and the steering goes bad on you.
Frames get most of there strength from the material used, form of the tubes, the structure of the tubes and reinforcements.
Single cradle frames explained - have a main backbone above the engine with one (or two) down tubes in front of the engine. Additionally the frame surrounds the engine with a sub frame going to the back.
Stressed engine frames explained - the engine become part of the frame (saving weight and space) additionals are bolted on to the frame, together it creates a stiff chassis.
Backbone frame explained - the engine sits below a top frame bar (tube). This kind of frame is mostly for smaller engine motorcycles
Diamond frame explained - a single tube hangs down from the backbone on which the engine is bolted, only then does it form a complete chassis for the motorcycle. Mostly used for smaller engine motorcycles.
Frame Rake explained - refers to the steering head angle which often is the same as the angle of the fork tube angle.
Frame Trail explained - refers to the travel distance of the wheels / frame. Said simply - the shorter the trail the more direct a motorcycle steers.
Wheel base explained - the wheel base of a frame refers to the distance between the wheel centers. (overall length of a bike is the distance between wheel ends)
Periodically check all bolts on the frame (frames don't need much maintenance) but do check all bolts often, you'll be surprised at what comes loose over time.
Over time the motorcycle (frame) might feel a little unstable this is often caused by worn and loose bearings (e.g. a clunk in the steering, drifting in a straight line, vibration in the bars, etc)
Anytime you are dealing with a motorcycle from a crash the frame will need to be checked. That's an expert’s job…really take care of getting into repaired damaged frames.
Frame maintenance should be a regular part of your service schedule – check swing arm bearings and linkage – lubricate swing arm and bearings – Check steering bearings – check nuts and bolts.

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