I thought we could have a little fun at my expense to start off 2020. We’re going to be doing a lot of independent aero testing this year and putting it up on our YouTube Channel (where I’ve posted almost nothing in the past), but I had this idea for quite a while to investigate how weight loss would effect my aerodynamic drag. After all, it would make sense that, as you lose weight, your body gets smaller; therefore, the area (the “A†part of CdA) you present to the wind gets smaller which lowers your drag. Simple!
Now, I’m a relatively big guy, which I can’t control. On the other hand, I’m also overweight for my size, and that’s something I absolutely can control. So, my idea is to test my drag every time I lose 10 lbs or so. As you’ll see form this initial video, the beginning number isn’t good, but I’m really interested to see where this goes.
Sorry for the amateurish video. I’m doing this pretty much alone, and don’t have the time, nor the knowledge, to put into video production. Still, I tried to have some fun. Feel free to comment, suggest, guess how low my drag might get. I’ll be losing somewhere in the range of 40-50lbs overall. I’ll answer comment made to the video on YouTube, but interested in the discussion here more.
Now, next week I’ll post another thread that will require Slowtwitch participation. I’m really looking forward to this one because the one comment I hear repeatedly is, “I’m not fast enough for aero to matter.” Hogwash. So, together we’re going to take a MOP mom who rides a road with aero bars, and see just how aero the ST collective can make her. Hopefully I’ll have an update on my weight loss progress as well.
but I had this idea for quite a while to investigate how weight loss would effect my aerodynamic drag. After all, it would make sense that, as you lose weight, your body gets smaller; therefore, the area (the “A†part of CdA) you present to the wind gets smaller which lowers your drag. Simple!
I have loosely made this argument for years to many when it comes to equipment choices, especially when they are selecting something that is a few grams lighter. I’ll be following and interested to see what exactly happens here. Losing 40-50lbs in the name of science sounds like a fantastic carrot to get fit and be healthier.
Thanks, Thomas. Yeah, I’ve been needing to get my arse in shape for quite some time, and had also been wanting to do this type of testing, so two birds…
I really have no idea how this will work out. I know it’ll make a difference, but I’m not sure how much. It’s really about losing size as I lose weight. I’m already quite a bit smaller than the original video, so I’ll test again hopefully this coming week or early next. I was supposed to test Saturday, but we went long and ran out of time.
Curious if changes in position are allowed. Seems like losing significant weight around the gut would allow you to get into a different position?
When all my weight is lost, we’ll change position for sure because you’re correct, I’ll be capable of better. But for now, I just want it to be about losing size. Smaller area = lower drag.
I think it’s going to be very difficult to isolate the actual reduction in drag due to body area reduction, since it’ll be conflated with both clothing changes and position changes. All the skinsuits and aero jerseys are not exactly able to fit a beer belly, and holding an aero tuck without losing power with said gut is also rather challenging.
I think it’s going to be very difficult to isolate the actual reduction in drag due to body area reduction, since it’ll be conflated with both clothing changes and position changes. All the skinsuits and aero jerseys are not exactly able to fit a beer belly, and holding an aero tuck without losing power with said gut is also rather challenging.
Both clothing and position were addressed in the video. Position will not change. I’ve started with a XXL LG Tri Suit, but also have an XL and L I’ll change to for better fit. In fact, for my next test, I’ll already need to size down to the XL. I have no trouble holding the position and power. It’s rather pedestrian for me as historically my aero bar is several cm lower. However, I’m purposely not riding in this position during this period of testing because one thing we do know is the more accustomed to a position you become, the lower your drag will be. The only time I’m riding in aero right now is when I’m testing.
It matters. Think about how nice it is to be 2nd wheel in a fast group ride behind a big guy versus a girl!
That’s just mass/size also. That doesn’t address what positions are possible on the bike. The bigger you are the less aggressive you’ll probably be able to be.
The rest of this is just babble:
It’s childish, but this is a beef I have with Zwift racing for time trials. Ain’t no way in hell people that big as some are can be able to hold the same aero position. They’d need a weight/height based lookup table for CdA adjustment or something.
I do TT’s on there with guys who hold the same 4w/kg but are putting out 50 to even 75 more watts because they’re the size of a refrigerator. Real life? Yeah, no way in hell they’ve got that good of a CdA.
I could see a case to be made for a larger body, especially in the middle regions, to allow air to flow more fluidly around the object. The belly fills in the gap between the chest and top tube. There are lots of aquatic mammals that aren’t very thin and are quite round that are also efficiently hydrodynamic. Perhaps the same set of rules can apply to a larger human on a bike.
Really looking forward to this data!
Although I’m pretty lean I have a 42inch chest and alway been curious how much my drag would change if I dropped muscle.
I thought we could have a little fun at my expense to start off 2020.
I love it, Jim… this is great!
“A” is one aspect, “Cd” is another. The beer gut is actually aero, so you’ll lose some there… Slimmer arms, legs, shoulders(?), and butt should help. My WAG if you drop to 192 lbs, and change nothing but going down in suit size, is a CdA of .285 from .3052.
Can you say more about the aero sensor and what protocol you use?
Have not had a chance to watch just yet Jim but just wondering if you explain how you are managing to lose so much weight? Any secrets?? That amount of weight loss is pretty amazing, I would love to just drop 10-15 pounds let alone 40-50!!
Slimmer arms, legs, shoulders(?), and butt should help. My WAG if you drop to 192 lbs, and change nothing but going down in suit size, is a CdA of .285 from .3052.