Question: Is a Skateboard helmet ok for bicycle riding?
Answer: Maybe. If it is certified to the CPSC bicycle helmet standard it is probably fine. Most of the skateboard helmets do have good coverage in the rear. And most of them are very round and smooth, an ideal shape to make sure the helmet will not snag on anything during your crash.

The typical skate helmet has fewer vents than bike helmets do, so they may be hotter in summer. And the liners in skate helmets tend to be on the thin side, so they usually do not provide extra protection beyond what is necessary to meet the impact standard.

The real problem for bicycle use is that there are other skate-style helmets not labeled for bicycling, and there is no legal requirement for those to meet any standard at all. Some may meet the much less severe ASTM standard for skateboard use. The difference is a drop height in the lab test of one meter for skateboard and two meters for bicycle. The skateboard standard tests with more than one impact in the same spot, unlike the bike standard. Some of them meet only a European whitewater standard, which seems a long way from skateboarding but lets them put a label in the helmet saying it meets something, and consumers don't know the difference. The ones we have seen used only the number for the standard, so you have no idea what it represents unless you have some numbers memorized.

Beginning in 2002 when we checked local discount retailers we found that all of their "skate" helmets were in fact bike helmets in the skate shape, certified to the CPSC bicycle helmet standard. Few were also certified to the ASTM F1492 skateboard standard. For better or worse, the manufacturers are testing the thesis that a helmet designed for a single impact can work for multi-impact skateboarding.

In late 2003, several manufacturers introduced helmets that they actually certified to both the CPSC bicycle helmet standard and the ASTM F-1492 skateboard standard. In this case, the helmet meets the performance requirements for either sport. That's ideal. We have a list of the ones we have found.

In short, check the stickers inside the helmet. If it does not have one saying it meets the CPSC bicycle helmet standard, it is not designed for the type of impacts you will encounter in bicycle riding. If it does not have one saying it meets the ASTM F-1492 standard, there is no guarantee that it can take the multiple impacts from skateboarding or radical skating on halfpipes and other places where falls are frequent.

And note that there is no US law that says a helmet being sold for skateboarding or roller skating has to meet any standard whatsoever. The manufacturers are mostly afraid of lawsuits if they don't meet a skateboard standard, but in fact they can sell anything at all as a skate helmet as long as they don't claim it is for bicycling. So look for the ASTM F1492 sticker inside the helmet if it is a "skate" helmet in addition to any CPSC sticker it may have.

You can also check our page on manufacturers with dual-certified skate helmets advertised as meeting the CPSC standard. And see our page on helmets for the current season for more.

Note that inline skating helmets (as opposed to skateboard or trick skating) are bicycle helmets. For example the ASTM standard is for helmets for bicycling or inline skating. You do not need a separate helmet for inline skating. It should have a CPSC bicycle helmet standard sticker inside. The comments above apply to skateboarding, or to trick skating where falls are constant.
Question: Is a skate-style helmet ok for skateboarding?
Answer: Maybe! If it is certified to the ASTM skateboarding helmet standard F-1492 or the Snell N-94 Multi Purpose standard it is designed for the multiple impacts typical of skateboarding. If not, even if it passes the CPSC standard it may be a one-impact helmet that you would have to replace every time you crash. We recommend that you pay attention to the standards labels, and choose a helmet for skateboarding that has ASTM F-1492 or Snell N-94 stickers inside. Again, see our page of helmets that are certified for both sports because they meet both standards