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Choosing Frame Sliders
Frame Slider Design And Installation
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 event 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 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.
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 requires 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).
Many manufacturers know that cost is a bottom line for most consumers, the second most important concern is the need to modify the fairing. To that end, many manufacturers will choose the configuration that offer to address these concerns - choosing a mounting position that is exposed and does not require fairing modification and by not using a well designed offset bracket that will increase production costs. Occasionally those exposed locations are far from ideal as they are not strong enough to support the slider during impact. As a consumer you will need to do your research. The cheapest and more convenient mounting locations may hurt you in the long run when an impact may end up cracking your frame and totaling your bike. At Motovation, we will never compomise our ideals and knowingly put out a product just to get more sales. The best mounting configuration is not always the most popular. Our frame mounted sliders are developed after careful consideration and testing to make sure that the risks of secondary damage is minimized. It is always a calculated risk to use frame sliders but the risks can be mitigated by diligent research and engineering.
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.
The one long bolt vs double threaded rod argument.
Why some manufacturers use a double threaded rod with nuts at both ends to secure the frame sliders is not immediately obvious. Despite the fact that these rods are much more costly to make. The answer is really quite simple and the reasons quite compelling.
1) With the double threaded rod/two nuts design, if you go down on one side, you only have to remove one nut to replace that slider. With a bolt head/nut design if you went down on the side that has the bolt head, you would have to remove the whole bolt and both sliders to replace the one on the side with the bolt head.
2) With a bolt head/nut design, if you went down and bent the end with the threads, you would not be able to remove the bolt without first cutting slider and the bent portion of the bolt off first. This is very hard to do as we have observed some SV650's that went down on track days. With the double threaded rod / double nut, you can remove the threaded rod or frame slider from either side.
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. If the slider you are considering does not have internal aluminum or metal collars they will not srong enough to withstand any real impact. Nylon or Delrin by itself is just simply not strong enough to be held down by an M10 or M12 bolt. 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 Blue and to properly torque the mounting bolts to the manufacturer's recommendations. If you're not sure check out our torque reference guide.
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 home or 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.
If you're still not sure, have a look at these pictures to help you make that decision.