It seems that most helmets test faster without a visor. I know that these things are highly individual, but is there a rough or ball park figure (or range) of how much ‘cost’ there is by keeping a visor on a helmet?
I have a LG Vorttice and prefer to ride with the visor and I am just wondering if the ‘cost’ in aero terms is at all significant. If so, then I can adapt, I am sure. If not, then I won’t bother. I only do TTs up to approx. 80 kms.
Thanks for any information.
There have been some other threads on this subject, so I encourage you to use the search function to see past discussions on this topic. Basically though, it can vary from helmet to helmet. It seems that many helmets do have better aerodynamics without the shield. But not all. However, speed gains/losses from the visor can be impacted by other independent variables too. For me, using the shield allows me to position my head “better” (always subjective I know). Why? When wearing glasses the top bridge of the glasses is right in my best field of vision when my head is in a comfortable and optimal position. So I have to crane my neck a little more, sit up a little higher, etc. These subtle changes can have more of an impact that the loss incurred by using a shield. The shield opens up my field of vision because there is no obstruction getting in the way. So I’m more comfortable, head placement is better, and safety is better because I can see everything without that, albeit small, blind spot. Everyone is a bit different in positioning. So while pure aerodynamics plays an important role, so does comfort that allows the rider to hold position.
So your cost question of time will garnish a lot of different answers.
you need to read through this thread . . .I think they answer it somewhere . . .I use the Giro Selector and as I recall it’s one of the few that might actually be better with the shield in place. I’m thrilled with that since I like how it quieten’s the wind noise significantly lol.
Aerocamp thread . . .
What studies have you seen where the helmet w/o visor tests better than the helmet w/ visor? All of the studies I’ve seen state that the visor is better for aero. The visor is also good for the reasons mentioned above - better field of vision, more ventilation (depending on set-up), less equipment to mess with.
I’ve seen people mention the aero thing recently but haven’t seen the data.
Well, mainly on here (ST) and in particular the thread referred to above. But none of these were quantified in terms of watts, time, etc.
I prfer the visor for all the reasons stated in these replies, but I just wondered if the saving that some have found by ditching the visor are significant.
Thanks.
Specialized has said their McLaren helmet is faster without a visor. It has been said as a critique to Contador, since he rides with the visor vs. sunglasses.
Actually, now you come to mention it, I do recall an online interview with Mark Cote of Specialised in which he said that they had tested every helmet available at the time of developing the McLaren and that none of them tested faster with the visor - including those designed to be used with one.
But, as usual, none of this was quantified in terms of watts or time, which is what my original question was really trying to get at.
Interesting, as that is different from the results of this study:
http://link.springer.com/chapter/10.1007%2F978-2-287-09413-2_50
“In road posture, statistical analysis shows that the visor has not a significant influence,
neither on drag resistance, nor on the drag coefficient. However, in TT posture and for
the whole heads slopes, the visor allows a significant decrease of drag coefficient (CD:
0.93 ±0.02 vs. 0.92 ±0.01) and thus of drag resistance (RD: 38N ±0.5 vs. 37.5N ±0.6)
corresponding to a gain of 1.54%.”
The study is from 2008 and newer helmets have been released.
From one of the same researchers in a different paper in 2011:
http://www.ncbi.nlm.nih.gov/pubmed/22084053 (the whole study can also be found, which is where this quote was taken from):
“For the whole helmet inclination values considered
in the present work, the visor is shown to produce a significant
decrease (1.32%) of the drag force. This net gain
reaches 1.56% for the low helmet inclination and raises
2.32% for the high helmet inclination value.”
I don’t doubt that there will be variations based on helmet design and position, but everything I’ve seen shows that a visor is aerodynamically helpful.
That’s helpful and the first time I’ve actually seen any value or data attached to this topic/question. Thanks.
It depends on the helmet, the person using it, probably a ton of other factors.
The answer is: There really isn’t a right answer.
From what I understand, most of the time a visor will make a helmet slightly slower - but that’s a generality that doesn’t apply to everyone. Sometimes the difference is very small (basically unnoticeable) and sometimes it’s more significant. Some helmets test faster with the visor. A lot of it has to do with how a visor is installed / applied. I’ve heard of people getting a wingspan to test just as fast/faster with their DIY visors.