Frame Slider Design and Selection
By Roland Lee
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 sports riders, 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 sport bikes 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 manufacturer 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 distributor for US based frame
slider and accessories company.
http://www.motovationUSA.com
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