I was wondering if anyone had any real world advice about using my ww helmet for mountain biking. Is it a good idea? I understand the difference between how each specific helmet manufacturers develop helmets with sport specific features, but in reality - couldn’t one just wear their ww helmet for both?
Sweaty!
– Last Updated: Dec-17-09 2:22 PM EST –
Sweaty!
I think the cycle helmets are designed for harder hits than the WW helmets are. The cycle helmets are really designed to take one "good" hit and become trash (like current automobiles).
WW helmets are designed to handle lower speed collisions, over and over.
Put another way, WW helmets are designed for routine and regular things. Cycle helmets are designed for things that people don't really expect to happen.
sweaty
Dont forget the sweaty part.
Bike helmet pads will absorb some of the sweat in the foam.
My helmet is sealed to prevent the pads from absorbing water.
actually
I think the impact protection of WW helmet will likely be ok. My bike helmet is a whole lot flimsier than paddling helmets.
However, does one really want to wear a fully closed helmet on a bike ride is another matter. You might end up needing a roll from the sweat that pool in the helmet! 
something like
The ProTec Ace with vents and without the full ear coverage would work. Not very different than what bmx cyclist wear.
I use ProTec because my head is too
fat for quality WW helmets. But I wouldn’t use ProTec Ace for mountain biking.
Try a Sweet L/XL. I’ve got a mallet, too
and they fit great.
Dogmaticus
Different objectives
WW helmets are designed for multiple impacts, which necessarily increases their weight and limits their energy absorbing ability. Bike helmets use a crushable foam and often a breakable shell to take up the impact.
… but hey, knock yourself out;-)
BMX vs mountain bike
The way I see it, BMX helmets are enclosed because the high likelihood of crashes. The drawback is cooling (the lack of).
So it’s the same problem as mentioned above. You can probably use a WW helemt for BMX. When it gets hot, you take the helmet off for a minute and put it back on. But do you want to wear a non-venting helmet for an hour of non-stop climbing???
Not interchangable
In gross non scientific terms the design criteria is different between the two styles of helmets.
A bicycle helmet is designed with a relatively thick layer of crushable foam which is designed to slow the deceleration of your head more gradually to help prevent your brain from impacting the inside of your skull.
In an impact with a sharp or pointed object a bicycle helmet will not be as protective as a helmet with a hard/solid shell so not so good for whitewater.
A whitewater helmet is more of a padded hardhat to prevent sharp rocks and bumps from cutting or penetrating your cranium. Its hard shell and comparatively thin stiff cushion will spread the load over a broader area (versus no helmet) but in a high G hit will not do much to help moderate the G force to the brain.
This is a gross unscientific simplification so if you want to correct or clarify please feel free.
I would not use a whitewater helmet as a bicycle helmet due to it’s lower G force reduction potential but it would be better than nothing. With that said, I sometimes bicycle shuttle a particular whitewater run and use my unvented whitewater helmet and damn is it hot as hell.
Bike helmets are too small
A beanie style bike helmet is useless for protecting your temple. The sad trend for ww and motorcycle is also the beanie. I have the old protec with side covers. It has saved my life more than once as I tried to roll in shallow water and smashed my head of a rock. Bike helmets appear to be junk in comparison
Tried it and it doesn’t fit. Would have
to gouge out some foam on both sides, which kinda voids the warranty.