Helmet Aero Mods

[CoyoteX]

I have read on here and a few other sites people doing a simple mod to their helmet to make it quieter and have less wind drag. It isn't a boat tail but that would probably look pretty strange on a motorcycle helmet anyway



I just used foam tape normally used for insulation. I was sealing up all the gaps in the face shield anyway so adding a bit more around the outside over the top was no big deal. I rode with it to work today and it definitely is better. I can go up to about 80mph without it trying to push my head backwards. It is also quieter, the low frequency booming sounds are way less. I stopped and adjusted it a few times, where it is at in the picture worked great for me. If you lean forward on your bike it might need farther back but it can be pulled off and re-stuck without much trouble for a few hours till the glue sets up on the tape.

I have one trip on it going to work but I did not drive my normal speeds I was going fast and slow and stopping to adjust the foam. I should get enough normal driving miles on it this weekend and next week to see if it is a measurable difference in mileage. I figure I need at least 300 miles or so on it then I can peel it off and try another 300 or so miles. This best test I can really think of on a bike, cause there is not really a good way to do an A-B-A test that I can think of. I guess if I had a lot of time and an iron butt I could do a 100 mile test loop for the runs and fill up between runs but I don't think I will be trying that anytime soon.

[trebuchet03]

For future experiments... I highly advise not to add a boat tail to the helmet... If you get in an accident, say buh-bye to motor/sensory skills below the neck. Being able to roll easily is much more important - but what you've got now doesn't look like a problem

[red91sit]

Originally Posted by Coyote X

I have read on here and a few other sites people doing a simple mod to their helmet to make it quieter and have less wind drag. It isn't a boat tail but that would probably look pretty strange on a motorcycle helmet anyway



I just used foam tape normally used for insulation. I was sealing up all the gaps in the face shield anyway so adding a bit more around the outside over the top was no big deal. I rode with it to work today and it definitely is better. I can go up to about 80mph without it trying to push my head backwards. It is also quieter, the low frequency booming sounds are way less. I stopped and adjusted it a few times, where it is at in the picture worked great for me. If you lean forward on your bike it might need farther back but it can be pulled off and re-stuck without much trouble for a few hours till the glue sets up on the tape.

I have one trip on it going to work but I did not drive my normal speeds I was going fast and slow and stopping to adjust the foam. I should get enough normal driving miles on it this weekend and next week to see if it is a measurable difference in mileage. I figure I need at least 300 miles or so on it then I can peel it off and try another 300 or so miles. This best test I can really think of on a bike, cause there is not really a good way to do an A-B-A test that I can think of. I guess if I had a lot of time and an iron butt I could do a 100 mile test loop for the runs and fill up between runs but I don't think I will be trying that anytime soon.

Very interesting idea! Some helmets already have kam-bach (SP?) on them

I was curious about the foam tape on the sides, how does it affect the neck loadings as you turn you head to the left and right? it seems like it would go from attached to unattached flow rather abrubtly as the foam tape gets angled more or less to the direction of airflow.

[bones33]

Good cross-pollination application idea. I'll test it with you for another data point. I am not expecting any mileage gains.

I use a Shoei helmet that came stock with a little wing thing on the back that goes about 8" across the back of the helmet. It is about 1/2" wide. Applying a flow seperator on the sides such as your suggestion may give additional benefit.

For your iron butt reference go to www.ironbutt.com. These guys are plain nuts. They ought to be FE nerds though to pack more miles in a day with fewer fill-ups.

BTW CoyoteX, I'm subscribing to your drive as fast as you can and get the best FE you can philosophy. My mileage dropped only a couple of points going as fast as I safely could in traffic - much more fun too!

[omgwtfbyobbq]

Originally Posted by trebuchet03

For future experiments... I highly advise not to add a boat tail to the helmet... If you get in an accident, say buh-bye to motor/sensory skills below the neck. Being able to roll easily is much more important - but what you've got now doesn't look like a problem

What about break away foam/paper mache? As long as it can't exert more force than the neck would normally see in an accident, I don't see how it could be a problem.

[CoyoteX]

When I turn my head I lose the benefits of having that strip on there and it goes back to the normal pushing on my head. It doesn't act any differently with my head turned if it is on there or not.

I did notice I get a bit of lift at a very high speed. I was doing 75 past a big truck going the opposite way and I could feel the helmet pulling on the chin strap trying to lift off my head. It felt kind of strange because usually it is trying to blow my head backwards pretty hard but this time it was just a little bit of lift with the regular side to side buffeting.

I think there can be some noticeable improvements in mileage by doing some basic aero mods. Considering there is no thought whatsoever put into aero on a bike there are probably lots of things that can be done that don't change the bike much but give a measurable mileage gain. I know dropping from 70 to 65mph on the highway gives me like 6mpg better. And driving 80 I drop down into the mid to low 40mpg range. I really should add all my gas log entries since I have put about 2000 miles on the bike in about a month but having to put an entry in every day gets a bit old.

beatr911: It gets a bit annoying sometimes when you do a mod that gives you better mileage then the next tank you drop back to normal cause you are going faster I keep thinking I need to start using some special driving techniques or go slower since I have done so many mods to the car and am only 10mpg or so over stock but then I realize I am easily bored and it would never last more than a few minutes before the pedal is on the floor again. I am way past the point of trying to get better mileage to save money. When I get time I will be spending a few thousand on a new tube frame and fiberglass body for my metro just to pick up like 2mpg or so, but it is all a fun hobby so I don't care.

[trebuchet03]

Originally Posted by omgwtfbyobbq

What about break away foam/paper mache? As long as it can't exert more force than the neck would normally see in an accident, I don't see how it could be a problem.

That's typically how aero helmets work (like the one's you may see in the Tour de France). The critical thing for a homemade version is... How do you know your manufacturing will break away as intended. It's the kind of scenario that you find out when it's time to test it in real life :/ That's one of the benefits of mass production - you can depend on repeatable results from the product.

[omgwtfbyobbq]

Just make it an order of magnitude flimsier (Izzat a w3rd?) than commercial stuff, so we know it'll break off no matter what. I mean, it may be a pain having to mold another one after we smack our helmet against a wall or something, but it's better than the alternative.

[kickflipjr]

If your not concerned about safety and don't have helmet laws then you could use a tt bicycle helmet. Well, it could at least give you some inspiration.

[CoyoteX]

Well 3 trips I consider reasonably consistent averaged .5mpg lower than 3 without the strip on the helmet. I will peel it off today and see what I get on my way to work.

Not really a perfect test but it seems kind of strange to me that I get worse mileage with it. Then again .5mpg is not enough of a difference to actually consider it a real test. I would put margin of error pretty high on this experiment. I guess if I had a gas station nearby with one of those digital pumps that went beyond .1 gallon increments I could get a bit better resolution on my mileage per tank. As far as helping mileage I guess the conclusion is it would be such a tiny amount one way or another it would be really hard without a windtunnel to get it right I will probably alternate weeks with and without it just to see if I can get any sort of pattern before the weather turns cold enough to end the riding season.