Amateur Aerodynamics for Silvio

[Eric Winn]

Andrew can you take a

Andrew can you take a close-up photo of how you attached the covers to your rims without interfering with the braking surface.

Also how do you keep the tape smooth along the arc of the rim circumference?

You've got me thinking of trying this on my Vendetta.

-Eric

 

[Andrew 1973]

Hey Eric

The disks are cut approximately 1/4" short of the brake track and the tape is lined up to the edge of the brake track, just like rim decals are. By pulling the tape gently as I adhered it around the rim, I was able to easily follow the arc of the rim while keeping the tape smooth and free of wrinkles.

I'll try to get some photos that explain this better.

 

[3WHELZ]

Chrome?

Andrew - I have never seen a Silvio 1.0 with chrome frame components. Is this modification that you made, or do you have a rare production run?

 

[Jim Gerwing]

Ted's X-wind question

In the month of August I had about 12 rides with my Vendetta which had both wheels disc-ed. I cycled along two way roads, what we call secondary highways. One ride had a significant cross wind component, one ride had heavy traffic, most of these rides were in light wind and after work day kind of traffic. I would cycle on a shoulder that averaged about 4 feet wide and I would ride in the middle of this shoulder. I do not recommend cross winds where the side on component is, say, 5 mph or greater. As for cars, they're okay for buffeting as long as one of them is not coming at you as they pass traffic on the other side ( this is quite scary, actually). Large traffic pushes you toward the ditch as there is a noticeable pressure gradient before it passes and then when it passes, it sucks you toward the middle of the road ( this is pronounced if it's a semi with a trailer). There is also a significant drafting benefit for about 10 seconds. So if the wind is light and the course is dedicated to the race (traffic controlled) I think an experienced cyclist could manage with a bike that has both wheels disc-ed, other than that it's going to be an adventure.
JG

 

[Jeremy S]

Dean, I believe Andrew had to

Dean, I believe Andrew had to strip the paint off his boom to repair it, and he stripped some more parts to match.

 

[Andrew 1973]

"Chrome" Frame Components

That's correct Jeremy. I wanted to spend more time riding and less time waiting for paint to cure, so I elected to polish parts of the frame. If I could do it again, I wouldn't. It was a pain in the backside to do so! I think it looks pretty sweet, but not worth the effort. Silvio black is where it's at, although Vendetta yellow is awfully nice too.

 

[Andrew 1973]

My Test Slope - 6.6% Grade

First, thanks to Charles for pointing me to MapMyRide.com. I was never much for tracking my riding metrics, so sites like this have escaped me. Based on the .31 mile run with a -105' elevation change, this hill is a 6.6% grade. Am I correct?

Would 42.34mph be a relatively fast downhill coast for this slope?

 

[Andrew 1973]

Or is it 5.8%

Now that I saved my route, the numbers have changed. There is a bit of a difference from 6.6% down to 5.8%. So now I am not sure...

 

[Ted]

Thanks Jim Gerwing

Thanks Jim. It's probably not worth the potential disaster for the small gain in performance.

 

[Andrew 1973]

Crosswinds...

I had my first experience with crosswinds today. A short gust of qind from the right pushed the Silvio and me toward the center line rather abruptly. It' a good thing that there was no wind on the group ride last week, or.I may have caused quite a situation!

 

[Andrew 1973]

Crosswinds..

Ooops. Double post.

 

[Eric Winn]

OK Andrew, so give us the

OK Andrew, so give us the Paul Harvey...

You know, so now we know the rest of the story.

Ditching the front disc and keeping the back? Ditching both?

-Eric

 

[Andrew 1973]

The rest of the story

I am still intrigued by the idea of cheap aero, so I am going to keep experimenting with the disc covers. My next trial will be a front disc only. I would like tonsee if I realize a benefit and it's cheap enough to try different configurations.

 

[Ted]

Would cutting holes ...

Would cutting x number of holes, say 1 or 2 inch diameter, in the disc cover in the gaps between the spokes, allow the wheel to be streamlined yet still allow enough "air" thru to offset any crosswind, or at least make it manageable?

 

[Andrew 1973]

I was thinking about holes!

Remember the Campagnolo front discs from the mid-1980's with the four big holes? That idea crossed my mind. Unfortunately, designing and making a cover that allows some air to pass through is beyond anything I want to attempt right now.

 

[John Tolhurst]

My thinking here has been

My thinking here has been that a tail fin behind the front wheel could be used so that side pressure did not turn the wheel, or by adjusting the size of the tail fin, you could adjust the degree of turn. Some is okay, because when a side wind arrives you have to steer the wheels downwind a couple of inches anyway, so that you are leaning into the air. Just don't say I said it was safe.

 

[counterpoint]

There's a $400 solution: get

There's a $400 solution: get a Chinese carbon wheel with 50mm rim. From what I've been reading today's designs are less susceptible to cross winds, and the aero gains are such that they make up for the slightly higher weight.

 

[Andrew 1973]

The real solution...

Andrew finds job > Andrew catches up on past due bills > Andrew starts a bicycle fund > Andrew asks wife's permission to buy new wheels > Wife approves with conditions > Andrew rolls bicycle fund into new kitchen remodeling fund