Effects of bindings/boots location on rollerski handling

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skiffrace
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Effects of bindings/boots location on rollerski handling

Postby skiffrace » Wed Sep 28, 2016 9:18 am

I wonder how does the location of bindings/boots affect the handling of the rollerskis?
Would moving the bindings/boots towards the back of the rollerski improve tracking but reduce maneuverability, and moving it forwards do the opposite? Or something quite different?
My rollerskis have bindings in the default location installed at the shop where I bought it, and now for the sake of science :-) I start to wonder if I can improve something here...

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Magnus Johansson
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Re: Effects of bindings/boots location on rollerski handling

Postby Magnus Johansson » Wed Sep 28, 2016 11:14 am

Interesting questions, Skiffrace. I think roller ski bindings shall -- if possible -- be mounted just as bindings on skis to give the best tracking and maneuverability. Many models won't let you do that unless you have feet small enough (often below size 36). I think roller skis -- just like skis -- should come in various lengths adapted to the length and shoe size of the roller skier, and this is how I construct my roller skis.

What is the default location for the bindings on your roller skis? How far from the balance point?
Last edited by Magnus Johansson on Thu Oct 13, 2016 12:44 pm, edited 1 time in total.

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Re: Effects of bindings/boots location on rollerski handling

Postby skiffrace » Thu Sep 29, 2016 8:48 am

My attachment point is at the balance point (weight-wise) of the rollerskis (+-)
However, it is at ~65% of the length (measured rear axis to front axis) - in other words 15% forward of the center.
Take a look at this video:
https://www.youtube.com/watch?v=l2wKhHlbIcY
This fellow (who uses the same rollerskis as I do) has the bindings/boot at least 6-10cm further back that I do.
When doing the classic diagonal style, he is able to comfortably lift the back of the rollerski off the ground, just like on snow skis.
I cannot do that with my setup, without risking off balance/crashing.

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Re: Effects of bindings/boots location on rollerski handling

Postby Magnus Johansson » Thu Sep 29, 2016 12:07 pm

skiffrace wrote:My attachment point is at the balance point (weight-wise) of the rollerskis (+-)
However, it is at ~65% of the length (measured rear axis to front axis) - in other words 15% forward of the center.
Take a look at this video:
https://www.youtube.com/watch?v=l2wKhHlbIcY
This fellow (who uses the same rollerskis as I do) has the bindings/boot at least 6-10cm further back that I do.
When doing the classic diagonal style, he is able to comfortably lift the back of the rollerski off the ground, just like on snow skis.
I cannot do that with my setup, without risking off balance/crashing.

The balance point is a weight-wise measure. I do not understand how the balance point on your three-wheel roller skis can be 15% in front of the middle point. Do you have very heavy speed reducers on the front wheels?

Keith Nicol's roller skis are clearly tail-heavy; he needs much smaller feet or very heavy speed reducers to get those roller skis balanced.

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Re: Effects of bindings/boots location on rollerski handling

Postby skiffrace » Thu Sep 29, 2016 12:22 pm

The balance point is a weight-wise measure. I do not understand how the balance point on your three-wheel roller skis can be 15% in front of the middle point. Do you have very heavy speed reducers on the front wheels?

Keith Nicol's roller skis are clearly tail-heavy; he needs much smaller feet or very heavy speed reducers to get those roller skis balanced


I meant that the attachment point of my shoes is ~15% fore of the center of the rollerskis *length*. In other words, they are 27''-long rear-wheel axis to front wheel axis, and the attachment is at ~18'' measured from the back.

Since these rollerskis are, as you see, tail-heavy, the balance point (now we are talking weight) is almost the same location as the attachment point. So, from the "orthodox" view point, it's at the correct location.

Again, Keith Nicol is using the same rollerskis as I do.
I can clearly see in the video that his boots/bindings are almost certain to be *aft* of the (weight-wise) balance point. I can see he lifts the back of the ski more easily because his boot is attached closer to the end.
I do have speed reducers on the front wheel, but their weight is far less than the extra weight of the double rear wheel, and that's why the balance point of those skis is aft of the (geometrical) center.

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Re: Effects of bindings/boots location on rollerski handling

Postby Magnus Johansson » Thu Sep 29, 2016 1:02 pm

skiffrace wrote:I meant that the attachment point of my shoes is ~15% fore of the center of the rollerskis *length*. In other words, they are 27''-long rear-wheel axis to front wheel axis, and the attachment is at ~18'' measured from the back.

OK, then you do not have the bindings at balance point but quite a bit in front of it so your roller skis must be very tail-heavy. I guess the balance point on your roller skis are around 10" from the rear wheels axle center.

skiffrace wrote:Since these rollerskis are, as you see, tail-heavy, the balance point (now we are talking weight) is almost the same location as the attachment point. So, from the "orthodox" view point, it's at the correct location.

No, if the bindings are mounted at balance point the roller skis are neither tail-heavy nor tip-heavy but balanced.

skiffrace wrote:Again, Keith Nicol is using the same rollerskis as I do. I can clearly see in the video that his boots/bindings are almost certain to be *aft* of the (weight-wise) balance point.

No, they are clearly in front of the balance point, and again, the balance point is only a weight-wise measure.

skiffrace wrote:I can see he lifts the back of the ski more easily because his boot is attached closer to the end.

Yes, Keith's bindings are closer to the balance point than your bindings but still clearly in front of it.

skiffrace wrote:I do have speed reducers on the front wheel, but their weight is far less than the extra weight of the double rear wheel, and that's why the balance point of those skis is aft of the (geometrical) center.

Yes, that is true.

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Re: Effects of bindings/boots location on rollerski handling

Postby skiffrace » Thu Sep 29, 2016 1:52 pm

OK, here is what miss
1. Is the balance point the location on the rollerski shaft that if you place it over your finger, the ski will remain level (balanced)?
2. How should your foot be placed in relation to the balance point?
I assumed (incorrectly?) that the pivot point where the boots attach to bindings (near the toes) should be exactly over the balance point.
What's the correct setup?

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Re: Effects of bindings/boots location on rollerski handling

Postby Magnus Johansson » Thu Sep 29, 2016 3:39 pm

skiffrace wrote:OK, here is what miss
1. Is the balance point the location on the rollerski shaft that if you place it over your finger, the ski will remain level (balanced)?
2. How should your foot be placed in relation to the balance point?
I assumed (incorrectly?) that the pivot point where the boots attach to bindings (near the toes) should be exactly over the balance point.
What's the correct setup?

1. Yes.
2. The boot shall have its toe bar over the balance point. In the classic style it is not unusual to have the binding and thus the toe bar of the boot 1 or 2 cm behind balance point so the ski or roller ski is a little tip-heavy.

Would you please measure where the balance point is on your roller skis? I guessed 10" in front of the rear axle. You would need very small feet (or a very heavy speed reducer) to have the bindings mounted at balance point on your roller skis.

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Re: Effects of bindings/boots location on rollerski handling

Postby skiffrace » Fri Sep 30, 2016 9:13 am

You were right - my shoes are way forward in relation to the balance point!
I wonder why the shop where I bought the rollerskis screwed this up so badly?
Even with my limited experience, I always had a vague feeling something is wrong with the way my rollerkis behave.
I will change my setup and report back how it works.

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Re: Effects of bindings/boots location on rollerski handling

Postby Magnus Johansson » Sat Oct 01, 2016 2:14 am

skiffrace wrote:You were right - my shoes are way forward in relation to the balance point!
I wonder why the shop where I bought the rollerskis screwed this up so badly?
Even with my limited experience, I always had a vague feeling something is wrong with the way my rollerkis behave.
I will change my setup and report back how it works.

There is generally very little knowledge both among producers and retailers when it comes to balance point mounting on roller skis. I don't believe this has always been the case. When roller skis became shorter in the 1980's the balance point mounting was sacrificed for a lighter and easier turning roller ski. Since then there has not been any talk about balance point on roller skis. It has even gone so far so a big producer like Swenor now has a brochure that confuses pivot point with balance point; see http://swenor.com/en/images/1.pdf.

Your feeling was correct all the time. Yes, change the binding mounting and report the outcome together with the measurements before and after the changed mounting. A photo would be interesting too. If you have SNS or Prolink bindings you can save space by cutting off the part of the rail piece your ski boots don't cover.

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Re: Effects of bindings/boots location on rollerski handling

Postby dcpattie » Thu Oct 06, 2016 6:00 pm

One thing I've been playing with is heel-to-toe drop within the boots. The ideal boot level is dead flat - with zero (heel-to-toe) drop. However, my feet have been killing me so I've played around with different insoles only to find most aftermarket brands really raise your heals - adding unnecessary drop - and thereby throwing off my balance. I finally found an insert that supports by flat feet but doesn't change the zero drop characteristics of the ski boot.
Dave in Nordic Virginia

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Re: Effects of bindings/boots location on rollerski handling

Postby Magnus Johansson » Sat Oct 08, 2016 12:28 am

How did it go, Skiffrace? Have you had the opportunity to change the mounting?

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Re: Effects of bindings/boots location on rollerski handling

Postby skiffrace » Sun Oct 09, 2016 5:07 am

Not yet, plan on doing that sometime in the upcoming week.

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Re: Effects of bindings/boots location on rollerski handling

Postby skiffrace » Thu Oct 13, 2016 9:48 am

I've made the change and took the rollerskis for a spin. Perhaps it's too early to draw conclusions, but my initial impression is that there is barely any difference, and if so, not for the better.
In the picture the black arrow points to the original location where my shoes were attached, the white arrow points to the approximate balance point.
I still have difficulty lifting the back of the ski, perhaps because current attachment is still fore of the balance point.
However, I think it was an exercise in futility.
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Re: Effects of bindings/boots location on rollerski handling

Postby Magnus Johansson » Thu Oct 13, 2016 12:28 pm

skiffrace wrote:I've made the change and took the rollerskis for a spin.[...] However, I think it [the changed mounting] was an exercise in futility.

Thanks for the report and picture. I think you should get real ski boots or roller ski boots with a proper ski binding. I recommend combi boots. You have an inch or two between heel and back wheels. It seems possible to cut away some unnecessary aluminum from the fork so you can mount a ski binding a little closer to balance point with the boot heel just avoiding the back wheels. The original binding mounting was crazy.


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