Grip physics?

Jan Gerrit Klok wrote:
Disproportional in what way? That heavy skiers have weaker or stonger
arms? I wouldn't be surpised if the tendency went either way. But I
suspect that it is so individual that it is hard to think about in in
general terms. No doubt that people in general get more oppurtunity to
exercise their legs than arms, but heavier people probably have more
muscle mass, that even untrained would be stonger than an untrained
person with less mass.
Not being disrespectful at all, but for a "heavier" person, the change of
the arms being relatively weak seems greater than the opposite. If the big
guy has some friendly soft spots, already the skinny lightweight with the
matchstick arms will end up stronger.
Even a body builder with phenomenal arm strength, would still just have a
similar strength/weight ration as the match stick, due to weighing twice as
much. Perhaps more explosive yes, but worth less in a 15km race I'm sure.

Yes, smaller (and certainly non-fat people) will almost always have a
higher strength to weight ratio. I thought the point being discussed
was arm strength as a percentage of total strength. And strength and
power are quite different. Power for larger folks is limited by the
cardio-vascular system and how it scales, but strength scales in a
different way. This accounts for the explosive power you mention.
Dubious value in a 15k for sure, but perhaps relevant to grip?

I'd be interested to know why XC Ski's are so narrow, and how that would
relate to weight.
It seems a really flexible narrow ski under a heavy and strong skier would
approximate a pole tip more closely, thus maximum grip. But does it really
work that way in practice, or is he better off with a longer-than-standard
grip zone, perhaps even wider?

This is very interesting. I think I will try to learn about friction.

Joseph

Lets be honest Joseph.
No 1 Your technique is probably wrong.
being as heavy as you are a 210 ski will be flat on the snow all the
way.
It is almost impossible to find a classic ski today that will give a
person of your weight a good grip to glide ratio.
So you should have wonderful grip at any rate.
at any snow conditions.
In climbing a hill on xc skis people tend to lean forward too much.
This will reduce your grip zone
and your grip in general.
Try and put your weight of your upper body on the toe of your boots ins
climbing. This will apply all your 220lbs on your real grip zone.
Also chose your wax well.
rw

rw wrote:
Lets be honest Joseph.
No 1 Your technique is probably wrong.

No doubt about it. But my new skis have made me much more aware of my
problems, and I'm on the right track!

being as heavy as you are a 210 ski will be flat on the snow all the
way.

That's how it was with my old skis. My new skis were special ordered
from the Madshus factory. With all my weight on one, it is almost flat,
rolling my weight to my toes flattens it. This is a big difference from
my old skis that gripped more or less all the time, allowing me to be
very sloppy. Now I have to really concentrate on my rythmn and weight
transfer.

It is almost impossible to find a classic ski today that will give a
person of your weight a good grip to glide ratio.

Glide is very hard for me to judge. On descents I usually have good
speed due to my weight to frontal area ratio, so I glide from everyone
else around, but it is not clear how much drag I have at low speeds
like while DP-ing.

So you should have wonderful grip at any rate.
at any snow conditions.

On snow it is like I am nailed down. Great! On ice, I guess it is my
poor technique that gets magnified.

In climbing a hill on xc skis people tend to lean forward too much.
This will reduce your grip zone
and your grip in general.
Try and put your weight of your upper body on the toe of your boots ins
climbing. This will apply all your 220lbs on your real grip zone.
Also chose your wax well.

;-)

It's snowing right now, and I am preparing for a night ski in a few
hours. Violet Special.

Joseph

rw

Joseph wrote,
Glide is very hard for me to judge. On descents I usually have good
speed due to my weight to frontal area ratio, so I glide from everyone
else around, but it is not clear how much drag I have at low speeds
like while DP-ing.

To test the length and place of glide zone and grip zone there are two
ways of doing it.
1. go to a hill so you can glide. On the way down, lean forward ( if
your grip zone is too long in the front, you will feel it hooking or
slowing)If this is the case start reducing the front grip zone 1/4inch
at a time.

lean backward if it is slowing or hooking do the same at the back.
Normally the back grip zone start under the heel.

2. Go to a shop with a test board and have them mark your grip zone on
your ski.
RW
Went for a skate today it was wonderful nice corn snow. Very fast.

rw wrote:
Joseph wrote,
Glide is very hard for me to judge. On descents I usually have good
speed due to my weight to frontal area ratio, so I glide from everyone
else around, but it is not clear how much drag I have at low speeds
like while DP-ing.

To test the length and place of glide zone and grip zone there are two
ways of doing it.
1. go to a hill so you can glide. On the way down, lean forward ( if
your grip zone is too long in the front, you will feel it hooking or
slowing)If this is the case start reducing the front grip zone 1/4inch
at a time.

lean backward if it is slowing or hooking do the same at the back.
Normally the back grip zone start under the heel.

2. Go to a shop with a test board and have them mark your grip zone on
your ski.
RW

The place I bought the skis did a thorough job of fitting and marking
them. They used a digital deflection micrometer to measure the
deflection for my weight. They also marked the skis individually at the
various deflection depths (0.0, 0.15, 0.1, 0.2, 0.3) fore and aft. And
recommended which one is right and left based on leg measurements. Also
very specific written instructions for which markings to use with what
type of wax, etc. There was a reason I drove 2 hours each way to go to
that store! ;-)

Went for a skate today it was wonderful nice corn snow. Very fast.

Sounds like fun. I just got back from a skate. A dusting of new snow.
Very nice.

Joseph

The place I bought the skis did a thorough job of fitting and marking
them. They used a digital deflection micrometer to measure the
deflection for my weight. They also marked the skis individually at the
various deflection depths (0.0, 0.15, 0.1, 0.2, 0.3) fore and aft. And
recommended which one is right and left based on leg measurements. Also
very specific written instructions for which markings to use with what
type of wax, etc. There was a reason I drove 2 hours each way to go to
that store! ;-)
Wow! I hope to find a store like that for my first pair of skis! Although
hopefully it's not as complicated for skating ski's which is what I'll
probably be after.

Went for a skate today it was wonderful nice corn snow. Very fast.

Sounds like fun. I just got back from a skate. A dusting of new snow.
Very nice.
Lucky B's!
I was lucky enough to hit sunshine today (contrary to forecast), it's
****ing out now.
Skated in cycling short+jersey plus a thin longarm underlayer, 15ºC, finally
proper spring weather after a louzy winter.
Managed almost 2 hours of slalomming tiny kids on slow rollerblades and
middle ages cyclists that seemed to be on a slalomming mission themselves,
involving phantom cones...
Enjoyed myself anyway, haven't been so sore in years, and good blisters as
trophees. :-)

Now how would Joseph's ski's glide and grip if they were 10% or 20% wider
and perhaps a bit thinner to get the tension correct and weight similar?
-glide slower, grip worse?
-glide slower, grip better?
-glide faster, grip worse?
-glide faster, grip better?
Doesn't a lightweight skier get a bit more ski surface per kg bodyweight? Is
three an optimum, and if so where, how does it work?

J

I wrote "More speculation....how about strength to wt ratio. It feels
to me that
arm strength is a big factor in classic, and if you're more of a
clydesdale, your ratio may be low."

Note that was strength-to-wt and not strength-to-power. So if you're a
touch better strengh-to-wt, then it's easier to get the grip wax to
grip because you're moving a bit faster, and you can carry your speed
up the hill a bit further. If you have better technique, it's easier to
get the grip wax to grip and you carry your speed up the hilll a bit
further. If you have better strength-to-wt and better technique, it
seems like the effect is squared and not additive, so you carry you
speed up the hill a lot further.

If two people are striding up a hill, and the front guy get one extra
stride in the tracks, it's amazing how much distance that amounts to
when you crest the hill. It's something like 5' per stride. So when I
stride behind someone who's a good classic skier, they can just bury me
and do it effortlessly. It's mainly a technique thing (meaning good
technique is really rewarded), but it seems like the relaxation they
have adds to the technique and the lower HR effect. Classic is one of
those things that's hard to do well, and it usually takes a long time
to do it well.

Jay Wenner

Bjorn A. Payne Diaz wrote:
I wrote "More speculation....how about strength to wt ratio. It feels
to me that
arm strength is a big factor in classic, and if you're more of a
clydesdale, your ratio may be low."

Note that was strength-to-wt and not strength-to-power. So if you're a
touch better strengh-to-wt, then it's easier to get the grip wax to
grip because you're moving a bit faster, and you can carry your speed
up the hill a bit further. If you have better technique, it's easier to
get the grip wax to grip and you carry your speed up the hilll a bit
further. If you have better strength-to-wt and better technique, it
seems like the effect is squared and not additive, so you carry you
speed up the hill a lot further.

I have noticed that effect. When I am able to keep some speed and
momentum, I have better grip. When I am slower (due to low power) such
that I have to re-accelerate myself with each stride, the depand for
grip is greater and sometimes I slip.


If two people are striding up a hill, and the front guy get one extra
stride in the tracks, it's amazing how much distance that amounts to
when you crest the hill. It's something like 5' per stride. So when I
stride behind someone who's a good classic skier, they can just bury me
and do it effortlessly. It's mainly a technique thing (meaning good
technique is really rewarded), but it seems like the relaxation they
have adds to the technique and the lower HR effect. Classic is one of
those things that's hard to do well, and it usually takes a long time
to do it well.

This is certainly true. There are people I can clobber on a bike that
drop me effortlessly on skis. My recent Birkebeiner was a good example
of the power of technique. According to many people on the online forum
at the race website the ski race should take about 10-20 minutes longer
than the bike race. It took me 3 hours more! My poor technique was
magnified by the difficult conditions. Also my cold conditions skis
which are stiff for cold conditions and extra stiff for my weight may
have been particularly ill suited to the soft warm conditions.

Does that make sense to other people that heavier people might have
more to gain from different skis for different conditions? (cold vs
wet)

Joseph


Jay Wenner

This is certainly true. There are people I can clobber on a bike that
drop me effortlessly on skis. My recent Birkebeiner was a good example
of the power of technique. According to many people on the online forum
at the race website the ski race should take about 10-20 minutes longer
than the bike race. It took me 3 hours more! My poor technique was
magnified by the difficult conditions. Also my cold conditions skis
which are stiff for cold conditions and extra stiff for my weight may
have been particularly ill suited to the soft warm conditions.
There's bike version of that race? Over snow? Sounds like fun! I always
thought a cyclist would be faster over prep'd snow than a ski. I used to
rate myself able to keep up with world class classic skiers, maybe just not
freestyle, riding my bike. I'm a very efficient bad conditions biker though,
learned that because of my tall height, where-ever I ride it's challenging.

I can imagine that a heavier skier that's been on skis forever maybe
inherently have better technique than a lightweight with the same ski
background. My a-few-pound-extra riding buddy cleans steep hils at the first
try that fit racers need multiple attempts for. And he hardly ever rides
offroad. It's just every ride he does is a grip/balance game.

Jan Gerrit Klok wrote:
This is certainly true. There are people I can clobber on a bike that
drop me effortlessly on skis. My recent Birkebeiner was a good example
of the power of technique. According to many people on the online forum
at the race website the ski race should take about 10-20 minutes longer
than the bike race. It took me 3 hours more! My poor technique was
magnified by the difficult conditions. Also my cold conditions skis
which are stiff for cold conditions and extra stiff for my weight may
have been particularly ill suited to the soft warm conditions.
There's bike version of that race? Over snow? Sounds like fun! I always
thought a cyclist would be faster over prep'd snow than a ski. I used to
rate myself able to keep up with world class classic skiers, maybe just not
freestyle, riding my bike. I'm a very efficient bad conditions biker though,
learned that because of my tall height, where-ever I ride it's challenging.

It's in the summer and is 89km long. It has to go around some swamps
the ski race can go over, is my understanding. To my mind it has much
more demanding hills than the ski race. It's billed as the largest MTB
ride in the world. 12,000 riders. Big fun.

http://birkebeiner.no/ritt_eng/

I can imagine that a heavier skier that's been on skis forever maybe
inherently have better technique than a lightweight with the same ski
background. My a-few-pound-extra riding buddy cleans steep hils at the first
try that fit racers need multiple attempts for. And he hardly ever rides
offroad. It's just every ride he does is a grip/balance game.