Jump to content
LEO_LEO

A fast question about the cruising speed of the v8

Recommended Posts

I weigh 85 Kg, which might be my cruising speed with a v8?

(...I'm thinking of buying a v8 )

Share this post


Link to post
Share on other sites

That depends on you... If you want, you could go 30 km/h all the time...

  • Upvote 3

Share this post


Link to post
Share on other sites
3 hours ago, LEO_LEO said:

I weigh 85 Kg, which might be my cruising speed with a v8?

(...I'm thinking of buying a v8 )

Generally the cruising speed would be between 22-25 kph - most of the time you don't hit the speed limit on a normal route. As @Ludwig mentioned, the power circuit in V8 would allow you to safely maintain 29-30 kph, but realistically it's never the case: not because of tech limitations but because of your individual riding routine.

Let me know who you're planning to purchase from, I might suggest some of my partners that have outstanding aftersales in Italy. 

 

  • Upvote 2

Share this post


Link to post
Share on other sites

Thanks, last year I bought the Ninebot and I thought 20 km/h were more than enough, now it is not enough.  I like the V8, but my doubt is next year I find myself in the same condition as nowI don't have the perception of the speed difference between a ninebot speed (20 km/h) and the V8

  • Upvote 1

Share this post


Link to post
Share on other sites

I know I will say something that could be judged very stupid, but my doubt (I never face planted) is that it is not so much the speed to determine the damage, but the problem is the face plant, lying on the asphalt 20 km/h or 40 km/h is not so different

Share this post


Link to post
Share on other sites
Posted (edited)
3 hours ago, LEO_LEO said:

I know I will say something that could be judged very stupid, but my doubt (I never face planted) is that it is not so much the speed to determine the damage, but the problem is the face plant, lying on the asphalt 20 km/h or 40 km/h is not so different

Lying on the asphalt isn't the big problem, agreed, hitting the asphalt or anything else is the problem. How hard you hit decisively depends on your speed. Chances are that parts of your forward speed is converted in rotational and/or downward speed and splash. 40km/h is like free falling from 6.3m, 20km/h is like free falling from 1.6m. Think about this difference for a moment. 

But even then, even if you manage to bent your knees and sit down smoothly on the asphalt at 40km/h, you wouldn't want to hit a pothole in this situation, let alone a curb. 

Edited by Mono
  • Upvote 1

Share this post


Link to post
Share on other sites
Posted (edited)

@Mono, my  theory, or better my sensation, is that doing a calculation, a knee breaks also to 20 kmh, but that at the level of probability, the rotation supplied naturally by the greatest speed compensates the trend to be planted with smaller speeds ...

Edited by LEO_LEO

Share this post


Link to post
Share on other sites
6 minutes ago, LEO_LEO said:

@Mono, my  theory, or better my sensation, is that doing a calculation, a knee breaks also to 20 kmh, but that at the level of probability, the rotation supplied naturally by the greatest speed compensates the trend to be planted with smaller speeds ...

I am not sure I understand a single word of this theory, but I guess you have to believe what you have to believe.

  • Upvote 1

Share this post


Link to post
Share on other sites

The force curve is not linear but exponential. As a very rough rule of thumb: every time you up the speed about 50% you more than double the forces in play.

If you're both lucky and have trained to fall the parkour/martial-arts way, you might dampen the forces by rolling. But even a stone small enough that you could hold it in one hand, could be enough to transform that roll to a grave injury.

The human body, while in many ways amazingly durable, is like an egg-shell when the speeds go beyond what we can safely roll through. Even if you could go faster than 30kph on a wheel from Gotway or Rockwheel, doing so without full gear would be rather foolhardy. Even beyond run-off speeds <15-18kph a helmet is a very, very, VERY good idea.

  • Upvote 2

Share this post


Link to post
Share on other sites
Posted (edited)
8 minutes ago, Scatcat said:

The force curve is not linear but exponential. As a very rough rule of thumb: every time you up the speed about 50% you more than double the forces in play.

FTR, it is not exponential, it is quadratic, but yeah, speed kills. 

Edited by Mono

Share this post


Link to post
Share on other sites
1 hour ago, Mono said:

FTR, it is not exponential, it is quadratic, but yeah, speed kills. 

Too long since I took math and physics me thinks...  :D

But yeah, it's quadratic. But the basics are still, speed and danger is not a linear thing.

Share this post


Link to post
Share on other sites
1 hour ago, Scatcat said:

Too long since I took math and physics me thinks...  :D

But yeah, it's quadratic. But the basics are still, speed and danger is not a linear thing.

Having said that, the main reason for this nonlinearity though is that a bone either breaks or it doesn't. So that's more a phase transition kind of thing B)

Share this post


Link to post
Share on other sites
On 6/7/2017 at 10:25 AM, Mono said:

I find the perceived difference between 20km/h and 25km/h huge. I felt myself somewhat limited on the MCM2s which goes maybe a little over 20km/h before to complain. Now, I have set the max speed of my V8 to 24km/h and I don't feel particularly limited. Of course on a straight flat and long street it's getting old easily (still the tiltback gives a little bit of spice then), but then I also don't like the risks involved in going much faster.

I'm absolutely with Mono on this one. I've set my 1st beep to 24 km/h and treat it as a "do no exceed" limit.

In fact, I can speak first hand how it feels to fall off at top speed on my Inmotion V5F+, and I can assure you the energies involved in falling at 24 km/h are about the limit of exiting unscathed. In my case I took a few steps and managed to run it off but the cost was a sore neck, some muscles soreness from muscle tears, and I partially tore off the sole of my boot. And my wheel disappeared. Blink and it was gone. Found it later in the bushes.

  • Upvote 2

Share this post


Link to post
Share on other sites

Once your body departs from the wheel it's mass has kinetic energy calculated as 0.5 x m x v^2  velocity measured in m/s, mass in kilograms 

So at 20km/h a 75kg mass has a kinetic energy of 0.5 × sqr(5.55556) × 75 = 1,157J

at 30km/h it is 0.5 × sqr(8.33333) × 75 = 2,604J

So increasing from 20 to 30 km/h (12.5 to 18.6MPH) means your body hits whatever is in its way with nearly two and a half times as much force. Even if it just means sliding over the ground you are going to tear an awful lot more skin off if not adequately protected.

  • Upvote 2

Share this post


Link to post
Share on other sites
3 hours ago, Mono said:

Having said that, the main reason for this nonlinearity though is that a bone either breaks or it doesn't. So that's more a phase transition kind of thing B)

Actually a bone can fracture without fully breaking ;)

 

Share this post


Link to post
Share on other sites
1 hour ago, Scatcat said:

Actually a bone can fracture without fully breaking ;)

Yeah, well, like a hair-line crack or fissure. In medical school though the teaching position has been that hair-line cracks count as broken too. The main categories, IIRC, are stable or not and dislocated or not and open or not (cracked skin).

Share this post


Link to post
Share on other sites
1 hour ago, Mono said:

Yeah, well, like a hair-line crack or fissure. In medical school though the teaching position has been that hair-line cracks count as broken too. The main categories, IIRC, are stable or not and dislocated or not and open or not (cracked skin).

I've had a couple of cracks in my life: elbow, toe and ribs, but no clean breaks. I'd count the fractured bones I've had as reasonably stable. They hurt like holy f-ing h-ll, but they didn't really move out of position...

I've been lucky so far, I suppose. Partly I think it is because I belong in the light-and-flexible-bone-structure group, but then the accidents I've had have been just on the right side of catastrophe. Sh-t like running into a goal post in soccer elbow first, because I didn't want to step on my kid and preferred to take the hit on my elbow rather than my head. Probably should have taken it on the head, the goal post would probably have cracked when my thick skull hit it... Like dropping an MC on my toe :D, and trying to dig a comforter out from under the bed and then loosing my balance mashing my rib cage against the bed-post.

But I suppose you're right, a hairline crack is a crack too.

  • Upvote 1

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


×