G-Force App

[eajracing]

Rode with a friend on Saturday morning who had a smartwatch of some variety (android I believe) and a g-force measuring app as we've always wondered how many G's we actually feel mid-carve.  You calibrate it so that standing sill you're measuring 1G.  Mid turn, he was consistently getting up over 4.5G.  Most interestingly, at least to us, was that between turns he was measuring zero.  I've always said that loved carving as it feels like you're flying, and now we know that at least for a portion of it, you are.

[scottishsurfer]

4.5g seems very very high, i would have thought it would have been more around 2.5 peak. Ask him to try a run with the watch in his jacket pocket as being on his wrist might be throwing it off a bit.

[AcousticBoarder]

Was just thinking that, how much is from his wrist? I think you'd get different reading on different parts of the body, but the arms can move so independently that it might be very out of wack

[dredman]

If you weighed 200lbs, at 4.5g’s your feet/legs would be supporting 900lbs.  Seems pretty high to me.  

I think someone who is very mathy ran the numbers and found 1.5+/-.3 g’s to be normal. If I remember correctly. 

Still fun data to play with. 

[Freezer]

Your friend's G meter is registering instantaneous G from bumps/vibration, not steady-state G.  I'm an ex-Air Force pilot and a current aerobatic pilot with a lot of experience with G forces, and I can tell you that at 4.5 G it's very hard to lift your arm up, and if you look down you can't lift your head back up.  At 4.5 G without using an anti-G straining maneuver most people start to go grey (loose color perception).  If you're pulling that kind of G in repeated carves you'd be physically exhausted and likely pretty disoriented after one run.  I'd be shocked if the real steady-state G is above 2.5.

 

[eajracing]

All good points.  Will see if we can try it against his body this weekend.  I'm more interested in the <1G's between turns than how big a number you can generate.  

[Freezer]

The best measurement would be to put the watch on his helmet.  The head is naturally stabilized and isolated from bumps.  Regarding the zero G between turns, that is entirely possible.

[Corey]

I'd say absolutely zero G.  Try riding with a backpack - I found it super-annoying, always bouncing up and hitting my head.  If that's not enough evidence, the large gaps between carves in the snow also work.  

[Chouinard]

On 3/11/2019 at 3:22 PM, Freezer said:

At 4.5 G without using an anti-G straining maneuver most people start to go grey (loose color perception).  If you're pulling that kind of G in repeated carves you'd be physically exhausted and likely pretty disoriented after one run.  I'd be shocked if the real steady-state G is above 2.5.

I calling your post bs! I’ve got grey hair and a grey beard that I never had when riding my Burton M6 AND after doing laps all day long I am physically exhausted. 

[Freezer]

8 hours ago, Chouinard said:

I calling your post bs! I’ve got grey hair and a grey beard that I never had when riding my Burton M6 AND after doing laps all day long I am physically exhausted. 

Ha!  You forgot to mention chronic hemorrhoids from straining against all those Gs for year after year. 

[b.free]

Made a video on my new GoPro 7. It has G-meter, check it out, does not look promising but fun to watch.

 

[TimW]

For a flat run it is quite easy to calculate the the G's you feel based on (overall body) inclination angle: 1/cos(inclination)

That gives you 2 G (absolute) for a 60°  and 3  G for a 70° inclination. That is for clean carving without cheating (putting any part of your body on the snow, which would lower the G's).

I don't think anybody can carve a clean 70° turn, so the 1.5 relative (=2.5 absolute) the guy is pulling in the video is a realistic maximum. 

Of course curvature in the run can add to that. If a concave section in a run would give you 2 G vertical (instead of only 1 from gravity), that would increase the total Gs. If you would also have the speed to get the centripetal force, you could theoretically double the numbers above.

Above neglects the inclination of the run, which would lower things a bit.

Tim

 

Edited March 15, 2019 by TimW

[scottishsurfer]

On 3/15/2019 at 9:28 AM, TimW said:

For a flat run it is quite easy to calculate the the G's you feel based on (overall body) inclination angle: 1/cos(inclination)

That gives you 2 G (absolute) for a 60°  and 3  G for a 70° inclination. That is for clean carving without cheating (putting any part of your body on the snow, which would lower the G's).

I don't think anybody can carve a clean 70° turn, so the 1.5 relative (=2.5 absolute) the guy is pulling in the video is a realistic maximum. 

Of course curvature in the run can add to that. If a concave section in a run would give you 2 G vertical (instead of only 1 from gravity), that would increase the total Gs. If you would also have the speed to get the centripetal force, you could theoretically double the numbers above.

Above neglects the inclination of the run, which would lower things a bit.

Tim

 

I would have thought G would have been determined more by speed and the radius of the turn rather than inclination angle.

Edited March 16, 2019 by scottishsurfer

[st_lupo]

On a flat horizontal surface you can use an equilibrium criteria to establish the correct force balance.  Knowing the gs and picking a speed the you could also calculate a turn radius.

[Freezer]

18 hours ago, st_lupo said:

On a flat horizontal surface you can use an equilibrium criteria to establish the correct force balance.  Knowing the gs and picking a speed the you could also calculate a turn radius.

Yep. Said another way, for a given speed and turn radius, there is a required bank (inclination) angle. That bank angle will produce a certain G load.  As noted by TimW, that applies to an unsupported carve, so if any part of your body is touching the snow and therefore supporting some weight, the G you’re pulling will be reduced.