Davenport Skeleton Sleds - information on DSS runners

I have stopped building skeleton sleds - my last year of construction was 2009.  I have had too many years filled with too much work, trying to satisfy the equipment needs of as many customers as possible.  I am now able to build runners for anybody who wants them, regardless of what type of sled they are using.  In the past, runner sales were restricted to DSS sled customers because there was not enough time to build extra runners for those with other sleds.  In fact, runner sales restrictions had been used since 1997.

2011 was my first year of building runners for other types of sleds, and there will be some time needed to learn what dimensions need to be different for other sleds.  If you are using something other than a DSS sled, please check the details on this page for more information on the dimensions of my runners.  If you need different dimensions on your runners to fit a different type of sled, you MUST tell me before I begin construction.  So far, I have built runners for sleds built by Bromley, Dukurs, Hass, Huber, Nigi-Tech, Parker, ProtoStar, S1, SAIT, Schneider and Walser, as well as a handful of different sleds built for individual use and not available to other sliders.  ProtoStar and SAIT sleds come in multiple designs with slight dimensional changes that can cause one year's runners to not fit a different year's sled.  The other builders have been more consistent with their dimensions.  Note that in all cases, the required dimensions were supplied by my customers - I don't measure sleds built by other builders and I can't guarantee that the dimensions I have been given will fit your sled.

Since 2004 the IBSF has distributed a single type of runner steel which is the only steel allowed in IBSF competitions.  The IBSF steel sold from 2007 to 2009 was too weak and many people had problems with runners bending and with rapid wear due to usage and polishing.  In 2010 the IBSF upgraded this steel, making it somewhat stronger while keeping the same chemical composition.  The updated steel is not all that much harder but the problems with bending have been considerably reduced.

There are a large number of options available when choosing your runners.  The primary choice that must be made is for the grooves that are cut into the rear half of the runner.  These grooves give the sled stability and control, and different grooves will be needed for different athletes, depending on a number of factors such as body weight and driving skill.  The grooves will leave behind a small ridge known as a spine or knife.  By changing the grooves, you change the shape and width of this spine which changes the depth the runner will bite into the ice.  Of course, different ice temperatures will cause the runner to act differently.  Hard ice will need a sharper and / or narrower spine to allow the runner to bite into the ice deep enough to give you enough control.  Difficult tracks will need a different groove than easy tracks because of the requirement for more control.

In general, there are two main factors that determine the amount of control you will get with a set of runners.  Spine width can be changed to give more or less control, and the angle of the edge of the spine can be changed to give more or less control.  Here are some sketches that give you a visual explanation of this.  Note that all sketches are approximate.  If I used the exact dimensions, the differences in the grooves would be much smaller and would be very difficult to see.

As you increase the width of the spine, the spine will not sink as deep into the ice.  This will give you less control, but it will also damage the ice less.  The key to sliding quickly is to damage the ice as little as possible.  Some damage is necessary, of course, otherwise the sled would be impossible to steer.  Enough control is needed to avoid making mistakes.

The normal men's spine width for all grooves is .040", or approximately 1 mm.  This is 20% wider than the normal women's width.  Computer machining code has already been written for every width from women's -20% (approximately 0.7 mm) to men's +50% (approximately 1.5 mm), in 5% increments.

runner spine width  

Similarly, you can change the spine edge angle to change control.  As you tip the edge of the spine outward and make the spine less sharp, the spine will not sink as deep into the ice.  It is also easier for the spine to ride up over the top of the depression in the ice when it is less sharp, allowing the sled to break into a skid.

One very important factor is how deep the runner sinks into the ice under high G-force inside corners.  In the straights without G-force, very little of the runner sinks into the ice.  Inside corners, the depression created by the spine can be quite deep.  When you tip the edge of the spine outward, the runner doesn't sink as deep into the ice in order to support the load caused by the G-force.  Changing the spine edge angle affects the depth of this depression much more than changing the spine width.

You can see the three main groove types that I sell, each of them using one of the three main choices of cutting wheel.  You can also purchase runners with edge angles half way in between each of these choices.

runner spine edge angle

Here is a close-up view of the above.  As you can see, I keep the spine width the same for these different grooves.  All that changes is the spine's edge angle. spine edge angle closeup

It is possible to build runners that use the same edge angle while using a different cutting wheel.  Because these runners have the same spine width and the same edge angle, they will have the same amount of control under low G-force where the spine does not bite deeply into the ice.  Inside corners under high G-force, grooves cut with the smaller cutting wheel will not need to sink as deep into the ice to support the load.  I have designated this with the term "imitation" - the smaller cutting wheel imitates the groove that would normally be cut with a larger wheel.

For those interested in the low control of the Super Big Wheel groove, note that there are two imitation choices.  The Imitation Super Big Wheel is cut with a cutting wheel one size smaller than normal, and the Double Imitation Super Big Wheel is cut with a wheel two sizes smaller.

IBW vs BW comparison

Most sliders do not pay enough attention to the damage they do to the spine while polishing their runners.  The geometry of the spine changes considerably when material has been removed through usage and polishing.  New runners will generally have a diameter of around 15.95 or 15.96 mm.  I have seen runners polished so much that they are no longer legal by the IBSF rules, which only permit a minimum diameter of 15.5 mm.  I would say that the average set of used runners that I see has had at least 0.2 mm removed from them.  I have seen runners that were only one year old that had been polished down to 15.6 mm.

As you can see from the sketch, it doesn't take much polishing to greatly change the geometry of the grooves.  This is why I sell training runners made from chrome moly, a steel which is much harder.  Note, however, that chrome moly will rust.  Of course, chrome moly runners are not legal for IBSF competitions.

polishing widens the spine

There are many experimental grooves you can try.  Some of them have been tested considerably, others are just ideas that haven't been tried by anybody.

The single groove runner is one experimental runner that has been well tested and has been in use for many years, winning many World Cup medals and an Olympic medal.  Because the groove is cut off-centre, there is a contact point which cuts into the ice, giving good control.  But because there is no second groove, the "spine" widens very quickly under load, and the runner doesn't sink very deep into the ice at all.  The high control of this runner is something that bothers some customers, who don't like the runner at all.  Others like it very much and use single groove runners almost all the time.  However, the single groove runner is easy to damage by wear or poor polishing practices which can lose the effectiveness of the contact point.

Single groove runners can be built with any of the cutting wheels using any of the normal edge angles.

single groove runner

Asymmetrical spines are an experimental runner that can act like a combination of a single groove runner with its off-centre contact point and a more conventional two groove runner.  If the contact point wears out due to usage or poor polishing, the normal spine width allows the runner to still act like a normal runner would. asymmetrical spine runner

Asymmetrical grooves are another experimental runner available.  One side of the runner acts like the sharper groove, giving a bit of extra lateral control, while the other side acts like the shallower groove, reducing the amount the spine sinks into the ice under high G-force. asymmetrical groove runner

The Top Cut runner is another runner that has been around for quite a while, winning World Cup medals as far back as 2000 / 01.  Under high G-force, perhaps the outer points on the outside edge of the Imitation Big Wheel groove will cut into the ice.  So, I developed a groove called the Top Cut with these points cut off.  The Top Cut is only available in a cutting wheel size that is slightly smaller than the Standard / Imitation Big Wheel cutter.  Polishing the groove can be a bit more difficult.  Due to the polishing problems, chrome moly runners are not sold with the Top Cut groove.

An experimental variant can also be built with extra clearance on the outer edges of the grooves.  Perhaps the Top Cut runners are fast because they don't trap any crumbs of broken ice inside the groove.  If so, is it perhaps a good idea to give extra clearance for crumbs or especially frost?  This "chip clearance" idea has never been tested by me, but it's not too difficult to build.  It will make the grooves more difficult to polish, however.  Only the various grooves cut with the Standard / Imitation Big Wheel cutter have enough room for this clearance cut to be effective.

Top Cut runner

One more experimental groove is the extra long gradual groove entry ramp.  The idea of this groove is to make the spine cut into the ice as gradually as possible, rather than suddenly as is the case with normal runners.  Originally this groove was cut only using the Top Cut cutting wheel, but now I use a rectangular groove entry ramp for the other cutting wheels and the extra long entry is available with any groove (the sketch shown corresponds to the Top Cut version).  The original extra long groove entry had a starting point closer to the front of the sled and an ending point (where the full depth of the runner groove is reached) closer to the rear of the sled, and this combination gave me promising results but also caused me some control problems.  Since introducing the concept, I've altered my program code generation and can now use any entry ramp length and any groove length desired by the customer.

It can be noted that in spite of its experimental nature, the original Top Cut extra long gradual groove entry ramp was used to win the men's gold medal at the 2010 Olympics.

extra long groove entry

Here are some important dimensions of DSS runners.  If you are not using a DSS sled, you will need to check these dimensions if you are not already certain that DSS runners fit your sled.  Again, if you need different dimensions on your runners, you MUST tell me before I start construction.

As far as I know, normal DSS runners will fit all sleds built in North America with the exception of SAIT and ProtoStar sleds.  2012 and newer SAIT sleds take a longer post - for older SAIT sleds, the post is also narrower and the runner is shorter.  2013 ProtoStar sleds are different than older ProtoStar sleds and have slightly different rear block dimensions and overall runner length, which are slightly different from DSS runners in any case.  European and Japanese sleds use 16mm runner blocks, Dukurs sleds also take a different post, and Schneider and Huber sleds as well as the newest ProtoStar sleds have lots of different runner dimensions.

DSS runner dimensions

Note that DSS runners come standard with 5/8" runner blocks to fit North American sleds.  If you are using a sled built in Europe or Japan, you will probably need to order runners with a 16 mm runner block.  However, some European sleds have been built to fit standard North American runners, so you will need to inform me of the exact block dimensions needed if you are not using a DSS sled.

Also note that you can order runners with a larger rear bend radius, if you wish.

DSS runner dimensions

All DSS runners come with a varying radius on the front end of the runner. DSS runner dimensions

One final important dimension is the starting point of the groove.  If you are not using a DSS sled, it's possible that your runners will require a different groove starting point due to a different location of the centre of gravity (balance point) on your sled.  If you do use a DSS sled, you can order runners with a different groove length or entry ramp length if you wish, but you must specify the dimensions.  Simply asking for "longer" isn't exact enough.
length of grooves  

As you can see, there are many choices available to you when purchasing runners.  The various experimental groove choices greatly increase the number of possibilities.  For basic two groove runners, there are 19 different spine widths available, everything from women's -20% (approx. 0.7 mm) to men's +50% (approx. 1.5 mm) in 5% increments, with each width available in 14 different spine edge angle / cutting wheel combinations (and if requested, I can even go beyond those spine width or edge angle limits, as long as the resulting cut meets the IBSF's rule of a 2mm maximum cut depth):

Considering the damage that is done to the groove geometry due to usage and polishing, there is no need to add any additional spine widths or edge angles that fit in between the above choices.  Used runners quickly change their geometry, and what you had when you bought new runners does not mean that your used runners still have the same geometry.

Of course, everybody wants to know the answer to the question, "what is the best runner for me?"  Unfortunately, there is no simple answer.  Every slider is different and has different abilities and different needs.  My basic recommendation is always to start with one pair of Standards for cold ice and one pair of Big Wheels / Imitation Big Wheels for warm ice.  After sliding for a year on those choices, you will know whether you want more control or less control.  It's possible that you will never need the extra control of the Standards, even on the coldest ice.  It's possible that you will always skid with the Big Wheels, even on the warmest ice.  There is no way of knowing that from the outside.

All DSS runners are sold polished on both the running surface and inside the grooves.  Runner guards, a wooden polishing block and a groove polishing tool are included with the runners.

If you are interested in purchasing runners but you have questions, please e-mail me.  Hopefully I will be able to provide explanations for you.

Davenport Skeleton Sleds - last modified Sep. 5, 2017