Helmet fitting issue
 

So I was replacing my old helmet with a new SA2010 model and I'm having trouble with the fitting. I'm using the same model gforce open face helmet as before but the large (my previous size) is sloshing around on my head and the medium is very tight at the forehead.

I would think you should err on the side of being to small? The helmet should fit tight correct? How many inches above my eye brows should it sit?

Many thanks

try a different manufacturer. what helmet were you using before? i find it hard to recommend anything other than the pyrotect pro airflow or the hjc ar10II.

G force pro phenom, nothing extravagant as I only use it a couple of times a year. Last one in a large felt great, current version of same model was to big in a large.

Try a different manufacturer. Not only is there a difference in their sizing but also there will be a difference between the design for individual head shapes. Obviously your 'tried and true' made some changes that don't match up to you any more. Yes, they should be fairly snug but too tight can become very uncomfortable in short order.

The helmet needs to be snug, but comfortable enough to be worn for a period of time.

I had the same issue (tight at my forehead).
But I noticed that you can push the material at the forehead with your thumbs (it's somewhat ductile) and the tightness goes away to some level.
(This is may not be a recommendable procedure but you don't intend to use it on a daily basis and still have your airbag and what not.)
However, after using it for a while I ended up buying an expensive brand helmet, which was just as snug but much more comfortable and lighter.

As few of mentioned, try on different brands.

BELL helmets have a more "european" crown; narrow / long

HJC Motorsports have a more round crown - seems to fit universally well.

Simpson - fits similar to BELL. Tried on co-worker's Sidewinder Pro, and my cheeks were squished making me do a fish face.

Never tried a G-force helmet, but three employees here went from G-Force to HJC Motorsports helmets due to comfort / padding / weight.

I found that if the helmet is just a touch too big, a head sock can help making it feel more stable as well.