S40 aero upgrades

[FinalStretchSeries]

Hello, I like crafts and I'm looking into some aero upgrades, as a bikepacker and aerobar lover (road bike), I want the best of both worlds here.
I have 45mm carbon wheels and these may be upgraded in the future.

Phase 1
I want to start of easy, by closing the rear triangle on my s40. There are 2 options, just follow the outer lines of the frame, as shown on picuture 1. The above sight would be a rectangular shape. The second option would be to start at the rear axle and go towards the back of the saddle, instead of having a rectangular, it would be a triangle from all sides.
Cardboard => plastic => Epoxy/Carbon maybe later on
Question: are either options worthwile? I've seen some rear triangles duct-taped on google images, but can't seem to find those at the moment.

Phase 2 a cover that covers the rear wheel.


Thank you in advance for your 2 cents on the matter.

Cheers, Lau

 

[IyhelM]

Not sure of the impact beyond cosmetics.
The one aero upgrade you should start with could be a tailbox to smooth out the drag generated by your head and shoulders - much bigger than any turbulences in the rear triangle.

 

[ak-tux]

I think a combination of a large tailbag and covering the rear triangle has a cumulative aero effect. I don't have any scientific numbers to qualify it but the Parkers once shared a wind tunnel result (for V20) and the covered rear triangle had some notable advantage. "This saved 3.8 Watts at 0 yaw and was neutral at 7 degree yaw."...the tailbox was about 7.5W at 24mph 0 yaw... Check https://cruzbike.com/blogs/blog/cruzbike-at-the-a2-wind-tunnel. I created mine using some fiberglass cloth. Nothing fancy. Used a piece of paper cardboard as a template.

 

[Mathew Fy]

I made a box out of Coroplast for the front part that included a piece of fender in front of the tire. Some Zip ties and silicone caulking was used. A door allows access. Then I completed the aerodynamic / aesthetic improvement using vinyl wrap.

 

[cpml123]

I think a combination of a large tailbag and covering the rear triangle has a cumulative aero effect. I don't have any scientific numbers to qualify it but the Parkers once shared a wind tunnel result (for V20) and the covered rear triangle had some notable advantage. "This saved 3.8 Watts at 0 yaw and was neutral at 7 degree yaw."...the tailbox was about 7.5W at 24mph 0 yaw... Check https://cruzbike.com/blogs/blog/cruzbike-at-the-a2-wind-tunnel. I created mine using some fiberglass cloth. Nothing fancy. Used a piece of paper cardboard as a template.


View attachment 20486

Wow that's a nice looking professional picture!

 

[IyhelM]

"This saved 3.8 Watts at 0 yaw and was neutral at 7 degree yaw."

Pity we don’t know with which wheel setup. Interaction with a full rear disc would be interesting.
Note that the noticeable effect of the moosepack is valid for the V20, you can see the turbulences caused by the bum of the rider, directly in line with said moosepack; with the more upright position on the S40 I’d expect less impact.

 

[ak-tux]

I made a box out of Coroplast for the front part that included a piece of fender in front of the tire. Some Zip ties and silicone caulking was used. A door allows access. Then I completed the aerodynamic / aesthetic improvement using vinyl wrap.

Great! Any pictures? ... It is said that pictures speak!

 

[IyhelM]

@Karl42 has a good aero setup with his tailbox wide enough to align with his shoulders.

 

[Karl42]

Hello, I like crafts and I'm looking into some aero upgrades, as a bikepacker and aerobar lover (road bike), I want the best of both worlds here.

By far the biggest aero upgrade you can make is probably to replace your S40 with a V20. You can still make the seat angle adjustable to get the same S40 seat angle for climbing, but in the flats and downhill the more reclined position is much faster.

 

[Mathew Fy]

Great! Any pictures? ... It is said that pictures speak!

An older pic. Currently I have yellow vinyl wrap only on the box area. https://forum.cruzbike.com/threads/post-a-pic-of-your-ride.15264/page-2#post-181906

The build is similar to @RojoRacing

What did you do to your Cruzbike today?

Sorry to hear. New blips in the future?

forum.cruzbike.com

 

[3bs]

on the 40,
1. the rear triangle is a great place to make a little coroplast box or sew up a bag like for the v20 to put stuff and smooth out the air at the same time.
2. a tail box makes a difference. my favorite is the original little carbon box. it is not the best aerowise, i just like it the best. the better the transition and the cleaner the end, the better it works, larry did extensive stuff on this. my own experiment suggest that a tail fairing that originates at the seat edge on both sides and truncates at the end of the rear wheel, or at the axle in a pointed vertical edge running up to the top of the rider head is the most effective. you can test the idea with thin coroplast zipties and duct tape. it is essentially the ultimate tailbox and would be spectacular for touring, but is a total sail in a crosswind.
3. a rear disc wheel is an easy improvement, even on the 40. can be quickly swapped out in big crosswinds and is much more manageable in ordinary crosswinds.
4. the n +1 solution to get a v20 is also a good idea, and why not find an s30 while you are at it.

 

[FinalStretchSeries]

I'm thinking of making a fixed box at the end, keeping the axle/Headrest line in mind. Afterwards, make a detachable cage out of either
1) threaded rods and wrap it with vinyl wrap
2) cardboard ducytape

Disc wheel is in the making

N+1 seems fun but will limit touring options. We have quite a lot of hills and this will make climbing them harder. Although the v20 saddle adjust is interesting.

First thing I need to do is adjust the Headrest, as I am on the smaller size.

MMy Garmin varia has been installed.

 

[FinalStretchSeries]

Please fire away, and brainstorm with me =)

 

[Frito Bandito]

How about something shaped like this?

 

[3bs]

@Frito Bandito fairing pic is a very classic take. if you look for tica fairings (m5tica) you see similar. it just depends on what you are trying to do.

look at some of @LarryOz own fairing experiements too. i will note however weight, volume and cross winds are issues to balance.

its all about controlling the flow of air off of your backside. that is where drag popagates. this is why so many velos and streamliners end in a tapered vertical edge. as such the shape as shown in pic two but with the vert edge just past the end of the wheel is the best play.

 

[Frito Bandito]

@Frito Bandito fairing pic is a very classic take. if you look for tica fairings (m5tica) you see similar. it just depends on what you are trying to do.

look at some of @LarryOz own fairing experiements too. i will note however weight, volume and cross winds are issues to balance.

its all about controlling the flow of air off of your backside. that is where drag popagates. this is why so many velos and streamliners end in a tapered vertical edge. as such the shape as shown in pic two but with the vert edge just past the end of the wheel is the best play.

Yeah, something that large and shape is gonna catch side winds, so being able to put on or remove quickly depending on the day's route would be nice, or maybe as a 2nd bike if the winds pick up. I'm not really trying to sell this now, but one thing that is nice about it is that it is fully enclosed. Once you put something inside through the hatch such as a tent, sleeping bag, jacket or other lightish stuff and cover it with a Ventisit style seat it is going to remain dry. If it could be securely mounted to an S40 with some mods then something like that could be pretty handy in preserving as much of the S40's current load carrying ability while helping to make it more aero.

 

[3bs]

my tica fairing comes off with 4 bolts i think. it is kevlar, not carbon. super thin, super light. picks up behind the seat and trails over the rear tire. i almost never run it even when the bike was on the road and not the wahoo. it always felt cumbersome. if i was on a tour however, i would use it and stow my stuff in it.

 

[FinalStretchSeries]

Phase 2.

Painters tape as vase layer because duct tape is pure evil to remove.

 

[FinalStretchSeries]

Damn this thing is fast. A bit sketchy in the rain though. Love it!
Feeling my quads a bit, and my wrists are sore.
Set my spd plates backwards, more pushing with my heels relieves my knees quite a bit.

I'm debating the width of the rear fairing:
- follow saddle width, seems more all-round functional, as I don't want to be swapping it on and off all the time
- follow arm width, best theoretical drag resistance

How big is the aero penalty and how much harder to handle would the wider option be.