Aero Deep Dive in The Specialized Win Tunnel – Ask a Cycling a Coach 188

aerodynamics

#123

From the literature I’ve read, aero > weight for up to ~6% for a Joe and up to ~9% for a pro.


#124

Maybe for that one I’ll just plug the numbers into that website.

Mike


#125

It’s worse than that since rolling resistance will be a much higher percentage of total resistance but the power only reduces linearly with velocity.

At 45 kph power assuming a Crr of 0.00944 (typical MTB tyre) a saving of 20 Watts is a 5.6% reduction in CdA which, over the same flat 40 km is a time saving of 1.76% (56 seconds)

The 20 kph power rider would go 1.37% faster (99 seconds)

Add in grade and the benefits of the skinsuit are probably pretty low.

Mike


#126

Here’s the tricky part though… you aren’t going to travel at that average speed much at all. All climbs will be slower speed, and all descents will be faster. Many people will run out of gearing during some of the descents if they are using a 1x. Probably makes most modeling not quite applicable.


#127

@DaveWh this would equate to about 7.5 minutes over the course of Leadville, but I think the benefit would be slightly higher due to high speed sections where you have spun out and during the trip back to Pipeline, which usually has around a 8-10mph headwind.

I think 10 minutes over the course of the day is probably what you are looking at, which is solid.


#128

That would be enough to put me below 9:30. If I drop 5lbs, and get my nutrition fully dialed, I that might get me another 10-20. And if I increase FTP by 5%, I’d be knocking on the door of 9:00. That’s a lot of things to come together however.

I need to best-bike-split this to account for the varying grades and speeds, lower weight, etc…


#129

That’s why I have a Best Bike Split account. Getting someone else to do that for you is always easier.

Mike


#130

One thing I don’t know is whether the same skinsuit would give similar watt savings in an MTB position compared to the TT position. I suspect that it may actually have a bigger watt saving and maybe even a larger percentage of CdA saving as it is effective over a greater percentage of the frontal area.

Has anybody done testing on this?

Mike


#131

Here’s just one of many options: https://www.specialized.com/us/en/remora-aero-storage/p/131464


#132

A latex tube will save 1-3 watts over a good butyl tube depending on the tire construction and size. A stiff, poor tire “masks” the benefit of a latex tube.


#133

A skull cap is insignificant if it is tucked under the helment, a cap with a visor is…parachute-like.


#134

I believe Conti makes a butyl tube which is just as light as a latex tube…and you don’t have to pump it up every day.


#135

Awesome. Thanks for the reply.


#136

I don’t think it’s the weight that’s the concern, it’s the flexibilty on the tube. The more rigid it is, the more power it takes to deform it and that takes watts.

So although the conti tube is the same weight, it might not take the same energy to deform it.


#137

Never thought of that.
Ya learn something new (almost) every day here on TR! :nerd_face:


#138

To the aero whizzes at Specialized: Can you create an aero seam/trip strip on your leg with creative shaving? Shave everything but a half-inch wide strip down the front? Maybe one each side of the leg? Maybe when you do the progressively-shorter shaving test, you could try some variations. Free speed!


#139

The drag reduction afforded by a skin suite was my big take-away from this AWESOME pod cast! You say they can be used in any discipline. Does that include triathlon? I’m concerned that a suit fit optimized for the bent over riding position will cause restriction of movement for swimming and running. What are your thoughts on a skin suit for Tri?


#140

They do it all the time. They have special tri skin suits that have minimal pads.

They usually go down to the elbow. You can also get sleeveless but I think sleeved is faster in general.


#141

Got my Velotec skin suit today. I’m 180cm and 72kg, 15% on Dexa, with most of my muscle and weight on my lower body. Bought a small. Fits perfect. If I was any taller or carried an extra 1 or 2kg I’d need a medium.

Chamois is mediocre, but for the price, I’m pretty happy since this will be a race day only wear and I’m only doing short races.


#142

I guess you didn’t use Velotec’s sizing chart for your suit. As a little shorter and presumably skinnier cyclist than you, would you recommend that I go for the XS? Or should I stick with Velotec’s sizing chart and go for the S?