Skyline times?

General Palm Springs area.

Re: Skyline times?

Postby Wildhorse » Mon Jun 11, 2018 8:07 am

I usually move more slowly going downhill. It seems to put more stress on my body, and I am usually tired from a hike by the time I go downhill.

I imagine that differences in times going up and down are at least partly affected by accumulated injuries as we age and by whatever traumas our bodies may be guarding against consciously and unconsciously.

My favorite hikes are slow and off trail. My speed on these hikes varies with the physical and navigational difficulty and with danger of falling.

And some days I am just slower, or faster, than others depending on how I am feeling physically and emotionally, and on the weather. I have learned much about myself on mountains.
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Re: Skyline times?

Postby Ed » Mon Jun 11, 2018 8:32 am

I was once speedy downhill, but am now there with Cynthia and WildHorse. After doing the downhill on even a moderate hike, I feel very beaten up. I dread the last few hours coming down the Vivian Creek Trail more than I do the last few hours going up Skyline. I am sure some of it is due to my wobbly knee, the rest to age.

Hiking uphill, I start off doing Naismith's Rule speed or better, then begin slowing down after a few hours. To match Naismith's Rule for the entire hike, a moderate one, I would have to hike 3 mph downhill. I am way below that.
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Re: Skyline times?

Postby zippetydude » Tue Jun 12, 2018 2:42 am

I should qualify my 60% statement. It is only valid where there is a normal, walkable (is there such a word?) trail. For example, if I started at Ramon and went up to the stone cairn, and turned around there and went back down then the rule would hold. If I started at the museum, then the super steep, rather technical descent on rocks with gravel and loose sand would probably be more on the 1:1 ratio mentioned above. On fairly smooth trails, though, I find the huge drop in effort makes a big difference. BTW I totally agree about the Vivian experience for those last couple of miles!

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Re: Skyline times?

Postby Wildhorse » Tue Jun 12, 2018 6:31 am

Hi Z, One reason I am slower going down steep trails is that I am often quite fast going up steep trails. But I imagine you are also fast going up. Did the downhill speed come naturally to you or was it a skill you developed?

I have guessed that my own slower speed downhill may involve muscle imbalances that I don't fully understand. Core work seems to improve my pace. From what I have read, it seems that asymmetries and traumas from injuries or repetitive stresses are constantly causing issues, such as the ones that slow me down. Of course, so many other factors affect performance. Weather, food, body systems, emotions, etc.
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Re: Skyline times?

Postby Ed » Thu Jun 14, 2018 9:43 am

zippetydude wrote:Downhill time is almost always 60% of the uphill time.


Zip,

Check Tobler's Hiking Function.

https://en.wikipedia.org/wiki/Tobler%27s_hiking_function

As I read the table, downhill time is about 2/3 of uphill time for grades of 10-15 degrees. So you are a speedy downhiller!
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Re: Skyline times?

Postby zippetydude » Fri Jun 15, 2018 8:05 pm

...or a lazy uphiller! BTW, I found the formula and the graph interesting, but I'm thinking that to represent reality it should probably be more of a bell shaped curve, or somewhat more parabolic at least. Still, it's all for fun and he's given it a great deal more thought and effort that I have, so I totally appreciate his efforts.

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Re: Skyline times?

Postby Ed » Sat Jun 16, 2018 10:07 am

It does seem like the function for speed should be curved at the maximum. But the reciprocal function for pace is not very sharply curved at the minimum. Some of the references are interesting, at least for those of us who are quant nut-cases, it seems there is quite a literature on this subject. There are various extensions of Naismith's Rule, Tobler's Function, etc. which have been empirically tested. The original data for Tobler's Function seems to have come from Swiss soldiers. Strange that they had no adjustment for altitude.

By the way, I calculated the ratio of downhill time/uphill time for 10 and 15 degrees, and it was 0.7. So you are looking even speedier on the downhill run.
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Re: Skyline times?

Postby pdforeme » Sun Jun 17, 2018 8:07 pm

My down time is generally 80% of my uphill time. My math is simple, that is, i live/hike mostly in NW hikes that are 4 miles up a canyon to a lake, then back downhill. So i'm just comparing the total up to the total down. I suspect some of the near parity comes from pausing at times on the descent to give the right of way to the uphill hikers.
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Re: Skyline times?

Postby pdforeme » Mon Jun 25, 2018 10:11 pm

Related to these various rules......other than taking a bunch of my own times vs vertical....has anyone played around with the ideal slope for fastest ascents? That is, straight up the hill or some gentle long switchbacked trail. We just finished some extremely steep hikes but our vertical time was only 1000 feet per hour (ok, 2800 vert gain over 1.5 mile barely switchbacked steep trail).

its in a sense a calculus problem which i'm not going to waste time on (you pick the hike with no choice of optimizing the route (min the time).
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Re: Skyline times?

Postby zippetydude » Tue Jun 26, 2018 4:06 am

I like your phrasing of the question. It is something that has come up in many different postings...why the PCT is so v e r y l o n g a n d g r a d u a l in its climbs whereas Skyline is abrupt and direct in its ascent and yet there are still shortcuts to make it even steeper...what is the most efficient and effective approach with regards to incline gradient? Well, here's my two cents.

If you want to enjoy the process and spend your time talking with companions hiking with you or looking out at beautiful views, the PCT approach is ideal. It tends to offer smooth trails (where you don't have to spend every second watching your footfalls to avoid tripping) with views from many different view points because it will weave back and forth across a mountain as it attempts to minimize the angle of attack, so to speak.

If you want to obtain the maximum workout and achieve the minimum time for a given ascent, then the greatest steepness that does not require handholds and avoids slippery (like sand on stone) footings will afford you the desired level of effort.

So, Snow Creek is a nice trail to amble up and have a wonderful time. So is the PCT heading north out of Whitewater if your goal is aligned accordingly.

Conversely, if you're focused on conditioning, the Tram Road offers steep inclines with excellent footing and increasing incline as an excellent training route.

Skyline's appeal is probably due to its excellent efficiency combined with both good footing and beautiful views. If you contrast this with Marion Mountain Trail, which is also very steep but affords few views, Skyline is the winner (at least for me). If you contrast Skyline with Snow Creek, Skyline offers the efficiency to complete the process and still take the tram back down and continue your day with minimal interruption. The PCT out of Snow Creek up over the peak and down to the tram is 31 miles, so it is going to required at least a full day. Beautiful views...yes. Lunch at Las Casuelas...no.

So, my guess is for maximum athletic efficiency,the steepest part of the Tram Road Challenge, or around 12% grade, will let you maximize ascent for a given distance because it is on a prepared surface at a precise angle of attack. On trails, the efficiency is probably roughly equal as long as the footing is good, as you can work steadily when it is slightly steeper than stairs, move faster when the grade is steep but walkable, and jog/walk quickly when the grade is around 12%to 15%. Lower than that, you're probably going to be able to run, so the efficiency will be reduced and your quickness, weight, and training as a runner begin to affect the outcome.

Hope that was not too roundabout to be of any value.

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