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Mar 06

Tuesday March 6th, 2012

Greetings and welcome!

I am getting an early start on my update today. It is supposed to be a nice day,  and I will be spending much of it outside.

A look at the latest forecast guidance suggests to me that it isn’t early week that we need to worry about as much as it is late week and the weekend.

Today looks like it will be partly cloudy and 43. It looks like the warmest part of the air mass will pass through overnight Tuesday night, when we are expecting a LOW of 40. Wednesday looks like mid-40s and rain changing to snow, but not a lot of either one (1-3?). The cold front is expected fairly early in the day, so we might luck out there.

The part that worries me is the Thursday through Saturday sunny days, and the warm temps for the weekend. Thursday and Friday are predicted to be in the mid and upper 30s, not bad, but with some sun. Saturday’s forecast of sunny and mid-40s and Sunday with light rain and upper 40s would probably bring some fast changing conditions with some traffic.

There isn’t much question in my mind that there will be places to ride this weekend. There will be sheltered trails and forest roads, and places like that. It is more of a question of how the sunny and high traffic areas weather the week. Will we be able to ride system-wide, or just some spots?

I made the journey to Lakewood & Townsend yesterday a little before sunset. The trails all looked good to go. The groomers had obviously been out. I didn’t see any rough stuff, and the trails along F and Hwy 32 looked very nice. I think I counted 3 sunny patches on hillsides along the way and two were where people had gone off trail and roosted the snow away in a sunny spot.

Here are some pix that Joe shot over the weekend..

Today there are two main things on the roster. One is declaring war on the snow in the driveway, and the other is riding the sled. The sled got the hose fixed, new plugs, and I am stocked with ample gas and oil. I even did a few victory laps.

The driveway is a mess, and with the ice base it is really hard to plow. I am planning a trip to get some sand to deal with the ice base underneath the snow, and then I will be hammering away getting more snow cleared out. It will probably only get harder as it starts melting and putting water on the ice base again, so today is the day.

That is pretty much it for the regular update. Read on for the fluff if you are moved to do so. If not, have a good Tuesday and thank you for visiting!

RJB

Monica commented with an interesting question..

Just a question why do the trails get so bumpy you know that wash board effect when there a lot of snowmobiles out? No one we asked seems to have a very good answer.

I will offer up my theory and then post a few links to other people’s theory. Hopefully some of you will comment as well with your ideas.

My theory..

Stutter bumps, and eventually whoopties form because of a deformity in the trail causes the suspension to rebound with down pressure behind the first bump or deformity. That causes valleys and crests. That part is fairly self explanatory.

My theory involves frequency. Most snowmobiles have a 121″ track with roughly the same footprint. They weigh roughly about the same, travel the same stretch of trail at about the same speed, and the suspension rebounds at a similar force and velocity. All of these factors end up within about a 25% variation.

What we end up with is a resonant frequency. Look at the stutter bumps as a sinusoidal wave form. They have a consistent peak to peak length just like a sound wave would, because we are almost all playing the same note in the same place as the other sleds.

I came across this when I was going across a sea of stutter bumps, and sped up to a speed where I could ‘get on top’ of the stutters and have a smooth ride. I changed one of the two changeable variables that made the stutter bump’s frequency, which was speed.

The other dynamic that you could change is having a longer track, which tends to bridge the stutter bumps. In effect, it would be playing a lower note. If we all had 136″ tracks, the stutters would be farther apart.

So my answer is that stutter bumps are representative of a resonant frequency caused by similarities in weight, track length, and speed.

Here are a few links to other ideas on the topic.

Link 1

Link 2

 

One last item… Chicago Mike the River Manager/guide over at Kosir’s Rafting sent me this one. It is the long wipe-out down the hill after a failed mountainside hill climb. Wow what a ride. It takes like 2 1/2 minutes for him to stop for the last time.

 

Happy trails!

RJB

 

 

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