[scootyman]

Earlier tonight, while my wife and I were on a ride, she dropped her helmet after removing it. It fell about 3 feet, but bounced off the side of her bike before actually hitting pavement. It's a Suomy Gunwind, about a year old, and here's our question: Is the integrity of the helmet compromised? Does it need to be replaced or can she continue to wear it with a sense of safety? Thanks for the responses.

 

[Duc_N_Har]

They usually say , if you drop it , you should get a new one.

 

[Herb]

If it fell 3 ft directly to the curb, I may think twice, but it sounds like the bike slowed it's fall. I say wear it. (I'm sure if you ask a retailer, they'll tell you to buy a new one... : )

 

[DaffeDuc]

If you have the $$ get a new one - otherwise you can use it but know that it's been dropped and the integrity may not be 100%. You might be able to get it radiographed (X-rayed) to see if there are any cracks in the material.

You can use physics to figure out the velocity at the time of impact... I think I remember hearing something about 25+ mph as being the number where you might want to replace it. don't quote me on it though.

 

[caxys]

If you want to figure out how fast it was traveling at impact, here you go. Assuming it was starting from rest:

first, calculate the time:
d = 0.5*g*t^2 where
d = vertical distance fallen in meters
g = 9.8 m/s^2
solve for t

or just do the square root of the quantity (d/4.9)

Then, calculate the velocity:
v = g*t

That'll give you m/s. If you want to convert to mph, multiply your velocity in m/s by 2.24.

OK, it's Sunday. That's enough. My head hurts.

 

[DaffeDuc]

If you want to figure out how fast it was traveling at impact, here you go. Assuming it was starting from rest:

first, calculate the time:
d = 0.5*g*t^2 where
d = vertical distance fallen in meters
g = 9.8 m/s^2
solve for t

or just do the square root of the quantity (d/4.9)

Then, calculate the velocity:
v = g*t

That'll give you m/s. If you want to convert to mph, multiply your velocity in m/s by 2.24.

OK, it's Sunday. That's enough. My head hurts.

3 ft = 0.91440 m

sqr rt of (d/4.9)
= sqr rt of (0.91440m)/4.9
= sqr rt of 0.1866122448979591836734693877551
= 0.43198639434357094537962275872751 m/s
= 0.43 m/s?

velocity of mph
= result of sqr rt of (d/4.9) x 2.24
= 0.43198639434357094537962275872751 x 2.24
= 0.96764952332959891765035497954961 mph
= 0.97 mph?

seems kinda off but guess it's correct

 

[scootyman]

So, is that 0.97 mph or 97 mph? If it's the former, doesn't sound too bad. The latter and we're in trouble.

 

[Bloodshot]

I wouldn't worry about it. I don't know anyone who rides a lot who doesn;t drop a helmet once in a while. Definitely not cause to replace IMO.

 

[DaffeDuc]

0.97 mph as in 97/100 mph (less than 1.0 mph)

 

[caxys]

Actually, the number you got, 0.43, is the time it takes to fall 3 feet, which is about right. Multiply that by 9.8 m/s^2 to get the velocity, and you'll get 4.2 m/s, which is 9.4 mph.

 

[DaffeDuc]

go figure... i got that 9 mph answer first then decided to do it again and got the 0.9 mph answer 2nd. guess that's why I'm not an aeronautical engineer.

 

[mitt]

I would guess that the manufacturers have to say "get a new one" even if someone sneezes on it. It is a liability thing.

In my opinion, I believe a helmet could withstand a small drop. I don't think there are brittle materials used inside. Most of the materials are soft and and semi flexible, so they would have to be bent or really compressed to damage.

Just like anything in life, do what you feel comfortable with, but I would wear it.

mitt

 

[ScottRNelson]

Helmets get dropped and I don't run out and replace them every time that happens. I bought a used one that had been dropped, but the previous owner had it checked by the manufacturer to determine if it was okay. That particular helmet doesn't get used a lot right now because it's the wrong color (red), but I'll use it when I finally get my red Multistrada.

Dropping a helmet three feet does not affect the impact absorbing foam liner at all, so you know that part is good. You would have to drop one quite a bit harder to affect the outer shell. Then you would have to crash such that the first impact hit the exact same spot for it to make any difference anyway.

I vote to continue using the helmet, but be more careful next time. A helmet that has been placed on the ground can't "fall off".

 

[CRASH!]

I concur that the shell is probably ok. X-raying it could give you some peace of mind.

After the shell the reason helmets are "one time use" items is that the impact absorbing foam inside compresses... and it doesn't come back. But because your head wasn't inside the helmet, the foam is just fine. That's not a problem in this case.

 

[Race_Day_Dennis]

I have X Ray'd and CT'd a few at work. It seems the foam does not crush on the drops I have seen. Without a head in the helmet it just bends with the shell. The crushing must come from shell bending and skull not.
We have a helmet saying around here $5 head $5 helmet. Some of us would put a pot on our wives heads. Can you feel the love?

 

[Herb]

 

[scootyman]

How would one go about getting a helmet X-rayed? And what's the cost?

 

[DaffeDuc]

take it to the local chiropractor or vet clinic and see if you can get it x-rayed... not sure on costs though b/c I don't have an x-ray unit. price of actual materials is negligible but not sure if they would charge the regular fee. cost depends on area where you live.

 

[vtwinman]

Heck, I say that helmet is junk!!!!I will give you 20dollars for it shipped to my door.....Ha!Ha!

 

[DaffeDuc]

better let me look at it first... don't wanna give anyone a crappy helmet!