Sorry for taking an issue off but it was a really busy season up here for us and it never seemed like we could catch up with all the work coming through. We had some good snow this year but also had periods of record setting cold and an unusually frequent strong wind. Even for us recreational mushers it was a challenging year.As I write this I am planning my last mushing trip of the season and looking at the large stable of broken sleds starting to occupy the area around the shop that will be the inspiration for a number of future articles. For instance, a couple of the sleds that have come in had been sold with an “unbreakable” label by the company. I am not here to debate any companies claim except in almost 30 years of working around sleds I have never yet seen any sled that a team of dogs couldn’t break. Over the years we have seen steel, aluminum, fiberglass, carbon fiber and titanium break in ways never imagined. A lot of trails are narrow up here and run tightly through some forested areas. If anything goes wrong with a team of significant power it will usually translate into significant damage. This is why we see a lot broken sleds, both home-built and commercial, come through the shop during the year. This gives us a unique perspective on what other techniques are being used and how they stand up to certain kinds of trauma. There is a huge difference between what works 90% of the time and those moments when suddenly everything goes wrong. It is at these moments that a sled’s toughness is put to the test.In my last few articles I have been writing about working with metal runners when building your own sled. In this issue I want to wrap up this subject for now by talking a little bit about brushbows and the connection between the tips of the runners. When metal runners first arrived on the scene a lot of mushers started building their sleds with just a triangle of ¼” UHMW as the brushbow. Over time I noticed that more builders were going back to either a traditional bow (Photo 1) or reinforcing the ¼” UHMW with a rim of thicker plastic (Photo 2). Both of these have really added to the stability of the front end of these sleds. The nice offshoot of the more traditional style of brushbow is the fact that you end up with a set of UHMW struts between the front of the sled and the flat of the runner. The UHMW controls the amount of force impacting the runner and restrains it enough to limit the amount of bending that occurs at the front of the runner. What you absolutely don’t want to do here is attach any form of rigid (i.e. metal or wood) strut between the front and the flat of the runner. You have to allow for a certain amount of flexibility or bad things happen when that force has to go somewhere. Photo 3 shows some aluminum angle brackets that split in this situation. Another consideration is whether to use a rigid piece of aluminum as a headboard at the front of the sled. When a crash happens, especially when a sled is moving sideways, the fronts of the runners are always in danger of being bent and you want to allow any force to be distributed rather than focused on one area. While aluminum does this easily, a thick piece of plastic can also do the trick. The difference is that the aluminum piece will weigh less and be less sensitive to the contracting in size that occurs in UHMW.When you are considering a material to use for your bridle it would be a good idea to go with iron rope. I’m seeing it on more and more sleds from freight sleds to race sleds. We have been using it more here on our sleds and it is often a requested retrofit on sleds that don’t have it. When you attach your bridle make sure that the connection point has a bolt that travels through the runner so that there is no chance of slippage. Connecting the bridle to the brake bracket is a good way to keep the force of the team controlled by the brake while not stressing other parts of the sled (Photo 4).One thing that I have realized is how metal runners have unleashed the imagination in some mushers. As the price of sleds rise it becomes more and more attractive to build your own. Using these runners offer a lot of possibilities but have pitfalls, too. I cannot emphasize how important it is to be honest in assessing your mushing skills while putting together any sled, but especially a sled built on metal runners. These sleds tend to be light and can really test the limits of control in a musher, especially with a larger team. Then when you put a bunch of weight in some of them, it can make the sled drive completely different. You can counter some of these problems by adjusting sled width and bed height but you always have to keep in mind that these runners have limitations. A few years ago I wrote an article for a Quest Annual on the trend in sled building. I commented at the time that I saw a rise in the number of “Nascar” type sleds that were good for racing but not very good at taking any kind of hits. And there is nothing wrong with that except that a lot of people end up using these race sleds in situations that call for something a bit sturdier and then end up bringing them into the shop for repairs. Remember that metal runners are great for race sleds and mushing in areas where there are not a lot of things to hit.Just a few observations from the broken sled crop this winter. In an earlier article I emphasized keeping your design and construction techniques simple. While I have seen some wonderful examples of simple design, I have been amazed at some of the rigs that have come through the shop this year. Some of these sleds have been a challenge to fix in a fully-loaded shop much less out on the trail where they were broken. So I will reiterate one more time: keep it simple and always be thinking, “if this breaks, will I be able to repair this on the trail?” By looking at what might go wrong you have a better chance of things going right later on the trail.Another note to pass on was the failure of arctic bungees up here this year in the especially cold weather. A lot of race sleds that had bungees built in for stabilization or control functions had some real driving problems when the bungees stretched out and stayed stretched. If you build a sled and know that you will be driving it in temperatures of -20F or colder you want to limit the structural use of bungee.Well that’s it for now and I’m off to take a final trip. See you next issue and until then happy sled building.David Klumb has been making dog sleds in Fairbanks, Alaska since 1980. David and his wife Joanne ran the 2006 Serum Run. For more information on Laughing Husky dog sleds, visit www.laughinghusky.com.