One thing that has always intrigued me was frame design. With out a frame we basically have a pile of random parts, but there’s more to it then just a place to bolt it all together. This is the beginning and end of how well your bike is going to perform. You can put the best suspension, biggest brakes, and lightest wheels you can afford on your bike, but if the frame is weak and twitchy all those killer parts are for nothing. In the day and age we live in, it’s hard to beat the quality and construction of the latest and greatest factory superbikes. Let’s face it. They have the time and money to put all the R&D and design into them they want until you have a super light, super rigid frame. Now that doesn’t mean we have to swear off the idea of designing our own. This is kind of the crème de la crème of building a special. A truly one off frame separates the men from the boys so to speak. For those of us with older bikes this can greatly help overall performance and handling by making the bike much more sturdy and responsive. But also on a styling note this is where you can really start laying out the look of a bike. The chopper crowd has been stretching and raking frames for decades. This was for a mater of style. But when you start building your own frame you can make it all work together. You can have the style and performance in one package.

Different Streetfighter Motorcycle Frame Designs :

Trellis Frames:

For those of you that have been around the fighter scene, you no doubt have seen the beautiful examples built by Spondon, Harris, RAU and some of the later builders such as Martek, Steelheart and PEST. The most common design of these frames is a trellis format, similar to Ducati and MV Agusta. Built from either large diameter aluminum tube or chromoly steel, they offer a very light and rigid construction, but also give the builder a range of adjustability in component placement and over all layout. Mounting points can be made to fit many different engine configurations and also allow for a range of suspension locations.

Backbone or Cradle-Style Frame:

The next form of frame configuration is the backbone style or cradle frame. Most commonly found in older bikes and traditionally styled cruisers. RAU has adapted a version of this to act as a stressed member frame. Instead of a full cradle frame that has mounting points for the engine to sit into, they use the engine to mount the frame. This style does away with the lower frame rails. It incorporates a large diameter tube for the “backbone” and a section of down tubes to connect to the engine mounts. Honda has also adapted this style frame on their Hornet line. This setup is not only very rigid but also allows to showcase the engine. The down side is the frame has to go over the engine witch can make the bike rather tall.

Twin-Spar or Twin-Beam Frame:

The twin spar or twin beam frame is one of the most commonly used frames among sportbikes. If you’ve owned a GSXR, YZF, CBR or ZX of the last 10 years you’ve ridden a twin spar. They are very rigid, and strong frames. They can be heavy and bulky compared to other examples but in recent years the manufacturers have come up with new technologies to help cut the weight while still maintaining the strength. Arguably not the prettiest of designs but can be made to work as eye candy if done well. Another advantage of this design is the ability to hold or hide some of your components or fluids. Case in point the Buell XB series with its fuel in frame design.

Monocoque Frame:

One of the most unique designs is the monocoque. This can be done a number of ways. A number of panels that bolt together, tubes that mount in triangulated shapes, even just bolting everything to the engine. It’s a complex structural design that pulls the machine together in a very unorthodox way.

As for materials these frames can be made from, the range is also large. Steel and aluminum being the most common, although there are examples that have been made of carbon fiber, stainless steel and titanium. All these materials require a certain amount of skill to work with. Steel is probably the easiest and cheapest although is the heaviest of materials. The up side is it is the most resilient to flexing forces and if designed right can weigh in very close to an Aluminum frame. Aluminum would be next up the scale but takes more skill to work with. Welding aluminum can be tricky. It melts faster then steel and you have to have a good working knowledge of this material for it to weld right. It is very rigid and strong though and also half the weight of steel to gain the same strength. Titanium is very expensive and hard to get in large quantities but is the lightest and strongest of the more common metals. Carbon fiber is also getting harder to get and requires a totally different set of skills to work with. It also requires quite a bit to gain the same strength as the aforementioned metals. It is brittle though and has been known to shatter under the right forces.

So how do we lay all this out and make it work? Well, like I said earlier, that’s what you have to figure out. I will say this. Start drawing lines from the steering head to the swingarm pivot and go from there. Look at some new bikes and how they are laid out. Specifically, look at there mounting points; steering, engine and rear end. Break out your imaginary pen, A.K.A. your finger, and start drawing lines from one point to another. I’m interested in what you’ll come up with. There’s a lot more to this as well, such as component positioning, center of gravity, rake, trail ride height etc., but we will attack these issues another time!

Shaun “Scrapyard” Kelly
Custom Fighters – Streetfighter Motorcycle Forum
Streetfighter Apparel, Art, and Project Bikes

Article Source: http://EzineArticles.com/?expert=Shaun_Kelly

Call them crash protectors, crash bobbins, fairing protectors or frame sliders, all these products ultimately seek to do one thing – protect your expensive bodywork or the essential and often expensive structural parts of your motorcycle from damage in the even of a fall or tip-over. The frame slider concept is as old as the proverbial ‘crash bar’ and today there are as many designs and brands as there are models of bikes. The proliferation of these types of products testify to the success of the idea of providing a sacrificial item to absorb some of the damage in the event of a fall. We are by no means experts on this concept nor were we the first to come
up with it, but in this article we hope to provide you with an unbiased view so that you can make an informed decision when you’re ready to put down your hard earned cash.

Cost:

Cost of the frame sliders must be appropriate to the items that they are designed to
protect. Price is not necessarily the best indicator of quality. Poorly designed frame
sliders made of the nicest shiniest materials may not serve their purpose as well as
well designed but less ‘bling’ ones.

Mounting Configurations:

The frame slider must be designed to mount securely onto a strong enough part of
the motorcycle so that impact forces can be adequately distributed or absorbed.
Here are some popular mounting configurations.

Fairing Mounted Frame Sliders

Sliders that mount onto the fairing with small fairing screws may provide some
protection in a minor tip-over but offer very minimal protection in a slide. These
sliders are not generally recommended for serious riders.

Frame Mounted Sliders – Direct

The most popular and viable mounting option is directly to a selected strong point
of the frame. Sliders with this design offer the most protection and impact force
distribution. The installation of this type of slider often require modification of the
fairing and in some cases like the Honda VFR800, as extreme as requiring the
modification of the coolant bottle. For this reason, many choose the first or the
third option as fairing modification can at times be quite intimidating. This option is
the most popular for serious sportsriders, amateur and semi-professional racers
alike as they provide the best protection for the money. One other thing to consider
when choosing these types of sliders is where they will be mounted to.

Many
models of sportbikes offer several places to mount them, frame slider
manufacturers all have their personal reasons for choosing the mounting location
for theirs and many of them make that choice for the wrong reasons. An example is
cost – a location that offers a two short bolt mounting location is cheaper than one
using a long through the engine bolt choice. The former being a much weaker
location. If you own an SV650 you will know what we mean. Another choice is the
use of a bracket so that cutting of the fairing is avoided – see below (Frame
Mounted Frame Sliders-Through-Engine Bolts).

Frame Mounted Sliders – In-Direct

To address some of the concerns owners may have about modification of the
fairing, some manufacturers have opted for a design that allows for the slider to
mount onto an offset bracket that then mounts onto the frame. This offset
introduces a whole new set of variables into the mix. Depending on the degree of
the offset, impact forces now include amplified torque stresses which will be applied
to the frame mounting points. Offset brackets will need to be of beefier
construction, but not so beefy as to stay intact during an impact while severely
damaging the frame mounting points. This is often the most costly type of slider
configuration as most brackets require ingenious CNC work and design. In some
situations employment of a bracket is a calculated risk, in others it is just not
feasible. No cut sliders are attractive to most bikers so do your homework and ask
the manfacturer questions before you buy them.

Frame Mounted Frame Sliders-Through-Engine Bolts

The third mounting option found only on certain models of bikes like the Suzuki
DL1000 Vstrom, TL1000S, SV650 and Ducati models of bikes allow for use of the
long, through-the-engine mounting bolt. This method is by far the strongest
available as impact forces are allowed to be distributed over a much larger area.
This is also the second more costly design as these long bolts are quite expensive
to manufacture. The design must be structurally strong enough not to break off
when encountering the various types of impact forces but not so strong that these
forces would be transmitted entirely to and damage the considerably more costly
frame mounting points. In other words you want to sacrifice your slider before your
fairing and then your frame in that order. It’s a delicate balance and there is no sure
way to ensure that any one design will accomplish this desired goal.

Frame Slider Material:

The choice of material used for the frame slider should be a balance of the following
3 requirements:

Abrasion Resistance – the material should be hard enough to be
able to slow the bike down in a slide and not be totally worn down to the bolt half
way through a slide

Structural Strength – the material should be strong but not brittle and snap off too
easily on impact

Energy Absorption-the material used should have some energy absorbing
properties but not be so hard that all impact forces are transmitted to the mounting
points or fasteners (solid steel or aluminum materials are examples of non-energy
absorbing materials).

Most high quality frame sliders today are made of some kind
of nylon or other for energy absorption and with aluminum inserts for strengthening
of the fastening points. The range of nylon types, with different levels of abrasion
resistance and “brittleness” used is also quite varied.

Fasteners and Components:

Quality of materials used, aesthetics and quality of workmanship should also be
considered when choosing the right frame slider for your bike.
Look for high quality anodized steel bolts. Black non-coated bolts will rust in a
week or less depending where you live. Stainless steel washers between your steel
bolts and aluminum inserts in the slider also reduce potential corrosion problems.
Socket head cap screws offer the smallest footprint allowing for a thicker and
stronger slider dimensions and are generally much more expensive then regular
hex-head screws. Nyloc lock nuts where applicable are another added safety
feature. True, these are all minor considerations in the overall scheme of things but
they all add up to the cost of manufacturing. One last thing to remember is to
always try to use some form of thread lock compound like Loctite and to properly
torque the mounting bolts to the manufacturer’s recommendations. If you’re not
sure check out our torque reference guide.

CONCLUSION:

Where does that leave you the consumer? Well, we all don’t want to think about the
day when we will be able to justify the purchase of frame sliders. The reality is that
as long as bikes have only two wheels, you can expect them to fall over sooner or
later. Frame sliders are one of the surest and least expensive ways to ensure some
protection for the expensive or sometimes irreplaceable parts of your bike. After all
some protection is still better than none. Think about broken rear brake levers, gear
shifters or even worse – punctured radiators or coolant bottles, when you’re miles
from civilization. The rule is the same in our opinion no matter what you’re
spending your money on – buy the best you can afford and don’t be afraid to ask
the manufacturer why their product is better than the plethora of other brands
available out there. Any good manufacturer will be very clear about what
differentiates their products form others so that you will be able to make the correct
purchase decision.

Author is the manufacturer and distibutor for US based frame slider and accessories company. http://www.motovationUSA.com

Article Source: http://EzineArticles.com/?expert=Roland_Lee